Astronomy

[prendrelemick]

I admit I don't understand dark matter, prendrelemick. Crawford's summary is interesting. I am also looking at one by Freeman and McNamara ("In Search of Dark Matter") just to make more sense of the topic.

Crawford mentions around page 9 something called "modified gravity", but she says the various modifications to the laws of gravity have not so far accounted for all the observations.

There seems to be two sources where error can enter:

1) Do the current laws of gravity correctly model reality?

2) Are we able to measure the universe accurately enough to answer questions about dark matter?

If both 1 and 2 are true, then we need something called "dark matter", but no one has found any so far.

In all of this there is also "dark energy" which seems to me to be a sort of "anti-gravity" mechanism allowing the universe to accelerate faster than it should based on assumptions about the big bang.

Another thing that keeps coming to mind when I think of gravity (and anti-gravity) are Qigong masters who have been reported to walk on water or people who levitate when they meditate. Given the laws of gravity that should not be possible. Now I know most people would dismiss these as stories, but then we have not found any dark matter yet either.

I just love all this. All day yesterday (because of your posts above) I was thinking, "suppose Einstien's "rubber sheet" Spacetime continuum had holes in it through to another dimension or universe, or ripples on it caused by the Big bang or something lumpy on the otherside of it. That would affect gravity as we experience it". The advantage of knowing next to nothing about a subject is kind of liberating sometimes. However I think it is probably right to look for answers within the known laws of gravity for the moment.

I think measurement issues are less likely, the sensitivity of instrumentation nowadays is beyond belief. I heard on the radio (In Our Time, BBC radio 4) that they are detecting a distortion in space of one thousandth of the diameter of an electron per metre to prove the existance of Gravity waves!!!!

In the end, dark matter is a theory that fits the observations, the mathematical predictions and the simulations - but..

[YesNo]

This is one subject I know next to nothing about as well. I don't even know enough about the laws of gravitation to calculate the orbit of some satellite. However, that doesn't stop me from speculating.

I don't trust the current measurements because I don't know how inaccurate they are. I don't even know what it means if someone gave me a margin of error. I have heard about the detection of gravity waves, but I think they need more precise measurements. Then is the theory correct? Are what they are measuring according to the theory really what they are measuring?

My sense of the margin of error is more intuitive. We don't, for example, know if there is a Planet 9 in our solar system. If our measurements in general are so accurate, I would think that we should know something like that or how can I be so sure they know they measured a gravity wave coming from the collision of black holes in other galaxies? They didn't get a prediction of the alleged black hole (radio source) at the center of our galaxy right. That radio source was supposed to have "eaten" something or other, which would prove it was a black hole, but that lunch did not happen. I do trust the measurements of the cosmic background radiation, but that is only because there is not much there to measure and instruments have been sent into space to get that information a few times. But what does that data mean? Then the theory comes into question.

[Dreamwoven]

The problem is made more complex because of all the dwarf planets in the Kuiper Belt, and other objects like meteors going round the sun but a great distance from it. We are starting to catalogue them but there is still a large margin of error.

[Danik 2016]

A paper on the dark matter. I read only the abstract, but it might be of interest. Didn´t so much relish the idea advanced by the Brazilian article that contained the link, that we all may have this dark matter inside us. Oh well, that would explain a lot.:(
http://arxiv.org/pdf/1609.01282v1.pdf

[Dreamwoven]

The whole business of dark matter is still too difficult to grasp. I read the paper that Danik refers to and am still not clear.

The item from Popular Astronomy, below, is interesting:

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 429 2016 September 11


NEW EXTREMELY DISTANT SOLAR-SYSTEM OBJECTS
Carnegie Institution for Science

In the race to discover a proposed ninth planet in our Solar System,
astronomers have observed several never-before-seen objects at extreme
distances from the Sun in our Solar System. The more objects that are
found at extreme distances, the better the chance of constraining the
location of the ninth planet that is predicted to exist far beyond
Pluto (itself no longer classified as a planet). The placement and
orbits of small, so-called extreme trans-Neptunian objects, can help
to narrow down the size and distance from the Sun of the predicted
ninth planet, because that planet's gravity influences the movements
of the smaller objects that are far beyond Neptune. The objects are
called trans-Neptunian because their orbits around the Sun are greater
than Neptune's. In 2014, astronomers announced the discovery of 2012
VP113 (nicknamed 'Biden'), which has the most-distant known orbit in
our Solar System. They also noticed that the handful of known extreme
trans-Neptunian objects have similar longitudes of perihelion. That
led them to predict that there is a planet at more than 200 times our
distance from the Sun. Its mass, ranging in possibility from several
Earths to a Neptune equivalent, is shepherding the smaller objects
into similar types of orbits. Some people have called it Planet X or
Planet 9. Further work since 2014 showed that such a massive ninth
planet probably exists, by further constraining its possible
properties. Analysis of 'neighbouring' small-body orbits suggest that
it is several times more massive than the Earth, possibly by as much
as 15 times, and at the closest point of its extremely elongated orbit
it is at least 200 AU from the Sun (over 5 times as distant as Pluto.)

Researchers are conducting a special survey for objects beyond Neptune
and the Kuiper Belt, and have covered nearly 10% of the sky to date.
As they find and confirm extremely distant objects, they analyze
whether their discoveries fit into the larger theories about how
interactions with a massive distant planet could have shaped the outer
Solar System. We are now in a situation similar to that in the
mid-19th century when Alexis Bouvard noticed Uranus' orbital motion
was peculiar, which eventually led to the discovery of Neptune. The
new objects submitted to the Minor Planet Center for designation
include 2014 SR349, which adds to the class of the rare extreme trans-
Neptunian objects. Its orbital characteristics are similar to those
of the previously known extreme bodies whose positions and movements
initially led astronomers to propose the influence of Planet X.
Another new-found extreme object, 2013 FT28, has some characteristics
similar to those of other extreme objects but also some differences.
2014 FE72 is the first distant Oort-Cloud object found with an orbit
entirely beyond Neptune. It has an orbit that takes the object so far
away from the Sun (3000 AU) that it is probably being influenced by
forces of gravity from beyond our Solar System such as those of other
stars and the Galactic tide. It is the first Solar-System object
observed at such a large distance.

[Dreamwoven]

This item in EarthSky explains pulsars very clearly, even to someone like me who is not trained in astrophysics:

http://earthsky.org/space/impossibly-bright-monster-pulsars

[YesNo]

That the ULXs could be coming from neutron stars rather than black holes was interesting although I don't see why black holes could not be pulsars.

[Dreamwoven]

Can you explain how that could be?

[Dreamwoven]

This post has one reply that relates to this issue:http://earthsky.org/space/impossibly-bright-monster-pulsars, that monster pulsars are perhaps huge "black holes", the Japanese authors suggest. Is this to do with dark matter?

[prendrelemick]

Dreamwoven: Dark matter is a theory that is based on universe wide observations, rather that solar system wide. Is that where you are having difficulty? The kuiper belt, dwarf planets, 9th ,10th, 11th planets beyond Neptune are negligible in their affects on this scale. In fact Newtonian laws are seen to be working perfectly well within the solar system - there are no discrepencies observed on such a small scale.

It's when you get to galaxy and galaxy cluster scale, and apply Newton's law to them, a huge discrepency is seen - there is extra gravity there - they are moving at a speed consistant with something of 10 times the mass they are seen to have.

If you say The law of gravity is consistant and known then that mass must be there. (There are many 'ifs')

Over the years many candidates for this mass (called Dark Matter) have been eliminated.

Scientists are now looking for sub atomic particles because they seem to 'work' when they run computer simulations, and there are theories that allow for their creation in the Big Bang.

This search is extremly difficult and so far the only 'success' has been eliminating possibilities.

[Dreamwoven]

Dreamwoven: Dark matter is a theory that is based on universe wide observations, rather that solar system wide. Is that where you are having difficulty? The kuiper belt, dwarf planets, 9th ,10th, 11th planets beyond Neptune are negligible in their affects on this scale. In fact Newtonian laws are seen to be working perfectly well within the solar system - there are no discrepencies observed on such a small scale.

No, I get all that, about the universe, not the star-system. And that, as you say,
"This search is extremely difficult and so far the only 'success' has been eliminating possibilities." We are at the very edge of research and know little about dark matter and black holes.

[YesNo]

From what I understand a neutron star is the result of a massive star collapsing so much that the protons and electrons merge into neutrons while a black hole is not the result of a star collapse but just a region of space where the gravity is high. I might have that wrong. Based on that, I suspect a black hole, being just a region of space, should not be "rotating" so that a pulsar effect can be formed.

Regarding dark matter, Freeman and McNamara ("In Search of Dark Matter", 2006) claimed (page 18) that the current thinking is that there is no dark matter within the disk of the Milky Way and the original suspicion that there was in the early 20th century was incorrect do to inaccurate measurements of the amount of gravitational mass. What that would mean in our solar system is that any gravitation discrepancy between the observed movements of the planets would be caused by some missing real, not dark, matter. The current dark matter is supposed to be in halos around galaxies rather that within the galaxies or clusters of galaxies, but it makes me wonder whether there aren't more measurement issues that will be resolved in the future.

The Triangulum II galaxy is supposed to contain a lot of dark matter: http://earthsky.org/space/a-nearby-dark-matter-galaxy-triangulum-ii This might be a good one to keep in mind. Since this is closer to us, we could expect better measurements.

[tailor STATELY]

YesNo: "Based on that, I suspect a black hole, being just a region of space, should not be "rotating" so that a pulsar effect can be formed. "

I have this romantic notion that the massive black holes in the center of spiral galaxies are the engines that provide galactic spin and that the lines of unimaginable gravitational force that is exerted upon the multitudes of celestial bodies are analogous to the arms of a mobile - being the black matter sought for. Probably not scientific in any respect but I thought I'd share.

Ta ! (short for tarradiddle),
tailor STATELY

[prendrelemick]

No, I get all that, about the universe, not the star-system. And that, as you say, We are at the very edge of research and know little about dark matter and black holes.

I wrote that for myself to be honest, to clear up my understanding of the subject.

Here is yet another article I read, about the distribution of Dark Matter. As yes/no said, most is in a halo around Galaxies. Within our Galaxy there is thought to be about 100 earth masses/cubic light year of dark matter, which is a teeny tiny amount. Nevertheless they are hoping to detect the odd particle deep down in an old gold mine in Sth Dakota.

http://arstechnica.com/features/2014/07/dark-matter-makes-up-80-of-the-universe-but-where-is-it-all/

[YesNo]

I'm trying to make sense out of how the cosmic microwave background data suggests the existence of dark matter. It has something to do with gravity pulling matter together and photons pushing it apart. https://medium.com/starts-with-a-bang/five-reasons-we-think-dark-matter-exists-a122bd606ba8#.vgjlfi7yh

That article also mentioned the failure of the LUX (Large Underground Xenon) experiment to find direct evidence of dark matter. But maybe they have found it by now.

[prendrelemick]

Those were my thoughts exactly.

I read somewhere (I've no idea where!) that they are going to upgrade the LUX experiment - basically by having a bigger tank of xenon. The calculation that they can expect one particle of DM a century per litre of xenon makes this sensible.

[prendrelemick]

I don't trust the current measurements because I don't know how inaccurate they are. I don't even know what it means if someone gave me a margin of error. I have heard about the detection of gravity waves, but I think they need more precise measurements. Then is the theory correct? Are what they are measuring according to the theory really what they are measuring?



This is from my memory of a radio programme (BBC "In Our Time",) which is like a fount of all knowledge to me, so apologies if it seems a bit vague.

The Earth based detector has many problems. It is a large 'L' shaped
structure. When a gravity wave comes along, space is distorted so that one arm stretches and the other contracts. This is measured by mirrors hanging on the ends of the apparatus that splits and re-combines light from a single source. It is an old technique called interferometry. If the wavelenghs of light are out of phase when recombined, then something has shifted.

Background 'noises' are a problem, and so is the small size of the detector. In fact the measurements are so fine even the vibrations of the mollecules within the mirrors have to be allowed for. It can even detect the Gravity field of a person walking past. But as G waves travel at the speed of light they can be discerned from the slower background stuff.

As you say this is not very satisfactory. There are plans to relocate into space where three satelites in a huge triangular formation can do a much better job.

All this is to confirm Einstein's prediction of the existance of Gravity Waves. They should be produced when something massive moves in an irregular way - or wobbles as you might say.

I think I remember something about G W's being detected recently with this equipment - but that was after the programme was broadcast.

[YesNo]

One thing I've wondered about is whether gravity waves move at the speed of light or slower. This would depend on whether the hypothetical graviton had mass: https://en.wikipedia.org/wiki/Speed_of_gravity#Direct_measurements_of_gravitatio nal_waves

[Dreamwoven]

Here is a post on Space by Hungarian researchers that consider whether a Fifth Force of Nature has been found: http://www.space.com/33750-fifth-force-of-nature-dark-matter.html.

[YesNo]

We'll have to see what happens to this possibly new protophobic force. It is interesting that when one finds a particle it could either be a form of matter or a force carrier.

[prendrelemick]

"The experimentalists weren’t able to claim that it was a new force," Reminds me of something Sheldon Cooper might say - What can you expect from mere experimentalists ?

[YesNo]

I found John Moffat's "Reinventing Gravity" at a used bookstore and so I am looking into MOG or modified gravity. This theory does not have dark matter nor black hole singularities including a singularity at the big bang. I think this would eliminate any time travel possibilities, but it does have a beginning of the universe out of a vacuum (nothingness).

Often I read the concluding remarks in such books prior to reading the book itself. Moffat mentions that an experimental test of this could come with the gravitational wave projects (LIGO and LISA). The various theories have different predictions about what data should be observed from the gravitational waves at the beginning of the universe. Using the electromagnetic spectrum we can go only as far back as the recombination seen in the cosmic microwave background about 400,000 years after the beginning. LIGO and LISA should be able to get evidence even earlier than that.

[Dreamwoven]

This article (http://www.universetoday.com/130882/stellar-ghosts-understanding-our-origins/) in Universe Today seems to be drawing together our knowledge of stars to suggest a number of outcomes in the life and death of stars. Small stars like our sun have insufficient mass to go through the later stages of such development. Plenty to read here and discuss.

[YesNo]

The first thing I realized from the article is that the Crab Nebula is the remains of a massive star's supernova.

I am still trying to distinguish between neutron stars and black holes mentioned in the artcile. Supposedly a more massive star is needed to make a black hole. Although it is out of date this article (2008) makes me wonder just how much anyone knows about these two objects: https://www.sciencedaily.com/releases/2008/01/080114162455.htm The matter in a neutron star is called "highly incompressible" where the electrons and the protons merge. This makes me wonder how matter can compress into something smaller.

[prendrelemick]

The first thing I realized from the article is that the Crab Nebula is the remains of a massive star's supernova.

I am still trying to distinguish between neutron stars and black holes mentioned in the artcile. Supposedly a more massive star is needed to make a black hole. Although it is out of date this article (2008) makes me wonder just how much anyone knows about these two objects: https://www.sciencedaily.com/releases/2008/01/080114162455.htm The matter in a neutron star is called "highly incompressible" where the electrons and the protons merge. This makes me wonder how matter can compress into something smaller.

I imagine it as the point where gravity can finally overcome the forces that keep neutrons as neutrons and they collapse or break up - Remember a neutron is not an elementary particle -and as quarks and gluons are infintely small there is probably a lot of space inside a neutron. that is because I can't think beyond my Newtonian world.

[YesNo]

If the star is just more massive and only compresses to neutrons that would give it more gravity. Here is an article about neutron stars and black holes that I am finding interesting, but don't quite understand: http://www.uni.edu/morgans/astro/course/Notes/section2/new10.html

There is the idea of something being "neutron degenerate", which I don't understand. It means that a neutron star that gains mass would become smaller, but they would still have some size. There is also the idea of synchrotron radiation, a non-thermal radiation caused by electrons speeding up in a magnetic field.

One thing the article mentioned is that black holes have mass but they have no size. I am not sure why that has to be the case. Could not a neutron star have enough mass so the escape velocity required is the speed of light? However, if they had zero size, they would be "singularities" much like the big bang singularity. That is the part that puzzles me.

-------------------

In reading Moffat's view of gravity it looks like the problem with dark matter can be viewed in three ways:

1) The measurements are bad. (The current theory of gravity would fit the observations if they were accurate enough.)
2) The measurements are not bad. (The current theory of gravity does not fit the observations.)
...2a) The Newton-Einstein theory of gravity is correct. (The position of those looking for dark matter.)
...2b) The Newton-Einstein theory of gravity is not correct. (Moffat's position, as well as others offering competing new theories.)

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY
Electronic News Bulletin No. 430 2016 September 25
PLUTO 'PAINTS' ITS LARGEST MOON RED
NASA
In 2015 June, when the cameras on the approaching New Horizons
spacecraft first observed the large reddish polar region on Pluto's
largest moon, Charon, mission scientists had never seen anything like
it elsewhere in the Solar System, and they couldn't wait to get the
story behind it. Over the past year, after analyzing the images and
other data that New Horizons has sent back from its historic 2015 July
flight through the Pluto system, the scientists think they understand
why the polar region on Pluto's largest moon, Charon, is red. The
colouring comes from Pluto itself -- as methane gas that escapes from
Pluto's atmosphere and becomes 'trapped' by the moon's gravity and
freezes to the cold, icy surface at Charon's pole. That is followed
by chemical processing by ultraviolet light from the Sun that
transforms the methane into heavier hydrocarbons and eventually into
reddish organic materials called tholins. The team combined analyses
from detailed Charon images obtained by New Horizons with computer
models of how ice evolves at Charon's poles. Mission scientists had
previously speculated that methane from Pluto's atmosphere was trapped
at Charon's north pole and slowly converted into the reddish material,
but had no models to support that theory. The New Horizons team tried
to determine whether conditions on the Charon (which has a diameter of
1,212 km) could allow the capture and processing of methane gas. The
models using Pluto and Charon's 248-year orbit around the Sun show
some extreme weather at Charon's poles, where 100 years of continuous
sunlight alternate with a century of continuous darkness. Surface
temperatures during those long winters dip to -257 C, cold enough to
freeze methane solid.
The methane molecules bounce around on Charon's surface until they
either escape back into space or land on the cold pole, where they
freeze solid, forming a thin coating of methane ice that lasts until
sunlight comes back in the spring. But while the methane ice quickly
sublimates away, the heavier hydrocarbons created from it remain on
the surface. Sunlight further irradiates those leftovers into reddish
material -- called tholins -- that has slowly accumulated on Charon's
poles over millions of years. New Horizons' observations of Charon's
other pole, currently in winter darkness -- and seen by New Horizons
only by light reflected from Pluto, or 'Pluto-shine' -- confirmed
that the same activity was occurring at both poles. This study solves
one of the greatest mysteries astronomers found on Charon, Pluto's
giant moon, and opens up the possibility that other small planets in
the Kuiper Belt with moons may create similar, or even more extensive,
'atmospheric transfer' features on their moons

[prendrelemick]

If the star is just more massive and only compresses to neutrons that would give it more gravity. Here is an article about neutron stars and black holes that I am finding interesting, but don't quite understand: http://www.uni.edu/morgans/astro/course/Notes/section2/new10.html

There is the idea of something being "neutron degenerate", which I don't understand. It means that a neutron star that gains mass would become smaller, but they would still have some size. There is also the idea of synchrotron radiation, a non-thermal radiation caused by electrons speeding up in a magnetic field.

One thing the article mentioned is that black holes have mass but they have no size. I am not sure why that has to be the case. Could not a neutron star have enough mass so the escape velocity required is the speed of light? However, if they had zero size, they would be "singularities" much like the big bang singularity. That is the part that puzzles me.

-------------------

In reading Moffat's view of gravity it looks like the problem with dark matter can be viewed in three ways:

1) The measurements are bad. (The current theory of gravity would fit the observations if they were accurate enough.)
2) The measurements are not bad. (The current theory of gravity does not fit the observations.)
...2a) The Newton-Einstein theory of gravity is correct. (The position of those looking for dark matter.)
...2b) The Newton-Einstein theory of gravity is not correct. (Moffat's position, as well as others offering competing new theories.)


http://astronomy.stackexchange.com/questions/748/how-does-neutron-star-collapse-into-black-hole I don't know how reliable it is, but this link describes the process - as far as it is known -It mentions Quark stars (I'd never heard of them,) and then plumps for unproven "strings" as the most fundemental matter. (Is that where mass and energy are finally the same thing?)


ps. it wasn't you who asked the question was it?

I can't answer your other question either, but suspect the answer is to do with the speed of light,( isn't it always!) eg the escape velocity reaches the speed of light just as the size of the massive object reaches zero.

[YesNo]

I hadn't heard of quark stars either, but they would be some way to put more mass into a neutron star without completely collapsing it to a black hole point. It is that collapsing to a point that puzzles me. If the escape velocity from the surface of the object is the speed of light does that mean that the "surface" must be an "event horizon" and no longer a surface?

Apparently Moffat has a way out of needing black holes, but I haven't read enough of the book to know what it is.

Although I have an account on the physics stack exchange, I have only posted items on the math stack exchange and that only after discussing number theory with desiresjab.

[Dreamwoven]

I Don't know, YesNo. All this about number theory is beyond me.

Lots happening just now, with a suspected supernova in Lupus: http://www.universetoday.com/131048/bright-binocular-nova-discovered-lupus/ that can be seen with binoculars. It is far south of us I'm afraid, bur supernovae are always a remarkable event - such incomprehensible force!

[Dreamwoven]

That link of yours, prendrelemick, was very interesting and useful. I learned a lot about the life of stars from it - and, of course, about their death in a gigantic thermonuclear explosion.

[YesNo]

I didn't realize that a nova happened in a binary star system with one of the stars being a white dwarf. It looks like it is an explosion of two stars.

[Dreamwoven]

http://earthsky.org/space/cassini-begins-epic-final-year-at-saturn

[prendrelemick]

I hadn't heard of quark stars either, but they would be some way to put more mass into a neutron star without completely collapsing it to a black hole point. It is that collapsing to a point that puzzles me. If the escape velocity from the surface of the object is the speed of light does that mean that the "surface" must be an "event horizon" and no longer a surface?

Apparently Moffat has a way out of needing black holes, but I haven't read enough of the book to know what it is.

Although I have an account on the physics stack exchange, I have only posted items on the math stack exchange and that only after discussing number theory with desiresjab.

Perhaps we could try and understand that escape velocity equation that is on your link. I'm not sure what the terms are (never mind the units) is R for radius, v for velocity, m for mass G for ? I notice everything on one side is divided by R so the smaller it gets the bigger the value. I presume that it represents the inverse square rule - Does that mean that if you halve R, V is squared? As you may now realize I know nothing of maths.

EDIT: Reading on further it seems once the escape velocity of the object approaches the speed of light, collapse must continue to a singularity as it can no longer hold itself up. The author also told us not to think about it too much! Look at the equation for the Schwartzchild radius - can it be equal to the radius of the actual object?


That link of yours, prendrelemick, was very interesting and useful. I learned a lot about the life of stars from it - and, of course, about their death in a gigantic thermonuclear explosion.

Yes it was good for that, but the stuff about string theory made me wonder how reliable it was even though the caveat "perhaps" was used. Isn't String Theory is going out of fashion at the moment. What really struck me was the miniscule size of the strings.

[Dreamwoven]

http://earthsky.org/space/cassini-begins-epic-final-year-at-saturn
Saturn is a fascinating Ice Giant and I look forward to the final year as Cassini plunges down for a closer look.

[prendrelemick]

I can't believe it has been up there since 2004. The video makes no mention of the different coloured regions on the planet's "surface" I wonder where abouts they are going to crash it.

[YesNo]

Perhaps we could try and understand that escape velocity equation that is on your link. I'm not sure what the terms are (never mind the units) is R for radius, v for velocity, m for mass G for ? I notice everything on one side is divided by R so the smaller it gets the bigger the value. I presume that it represents the inverse square rule - Does that mean that if you halve R, V is squared? As you may now realize I know nothing of maths.

EDIT: Reading on further it seems once the escape velocity of the object approaches the speed of light, collapse must continue to a singularity as it can no longer hold itself up. The author also told us not to think about it too much! Look at the equation for the Schwartzchild radius - can it be equal to the radius of the actual object?


G would be the gravitational constant: https://en.wikipedia.org/wiki/Gravitational_constant

There is some question in that article about whether it is a constant like pi, unchanging for infinitely many decimal places. I assume a physical constant must break down at some point, but maybe those gravitational wave instruments will be able to get good measurements of it. If it does change, then an explanation for that change would be needed.

From reading Moffat, there are three kinds of postulated black holes: mini black holes, black holes from solar collapse and large black holes at the center of galaxies. The evidence for their existence comes from measuring the motions of objects around them and calculating how much mass would be needed to keep those motions going and then assuming it is caused by a black hole since the mass is too large to be a neutron (or quark) star.

However, a prediction that a cloud would fall into the black hole at the center of our galaxy didn't happen last year: https://en.wikipedia.org/wiki/Sagittarius_A*#Discovery_of_G2_gas_cloud_on_an_acc retion_course

That makes me question whether there is a black hole at the radio source Sgr A*.

[Dreamwoven]

http://www.universetoday.com/131081/mercury-tectonically-active-shrinking/

The Messenger probe sent by NASA has been investigating this hitherto little known innermost planet. A landing probe is to be sent there to investigate further.

[Dreamwoven]

I didn't even know that a probe was sent to Mercury, nor that further investigations by a second probe will be taking place.

[YesNo]

I didn't know Mercury was an active planet. Also being "active" appears to mean it is "contracting". I previously thought that just meant the surface was moving around because of internal heat. Perhaps the Sun also provides some of the energy to keep the planet active.

[Dreamwoven]

When you think about it, NASA has worked wonders in exploring the solar system. From vehicles on Mars, to exploring every planet and dwarf planet its an accomplishment that has hugely enriched our lives.

[prendrelemick]

Meanwhile today, the Rosetta probe is going to be crashed into comet 67p they are hoping to get 4 closeup pictures, but the slow data transfer might be a problem. The Comet is thought to have the consistancy of frozen cigarette ash, so crash might be the wrong word.

[Dreamwoven]

The European Space Agency (https://en.wikipedia.org/wiki/European_Space_Agency) is a co-operative project between a number of European states (it is separate from the European Union and is funded by European states directly). It is a much more modest affair than NASA, but has achieved surprisingly good results considering its limited budget. The James Webb Space Telescope (https://en.wikipedia.org/wiki/James_Webb_Space_Telescope) is its latest development due to be launched in 2018.

[YesNo]

Maybe the Rosetta probe will just fall through the comet? In that case, I hope it survives to continue sending data after the crash.

[Dreamwoven]

http://www.universetoday.com/130961/five-new-neptunian-trojans-discovered/

There are thousands of satellites captured by Jupiter that have been identified and named to date. The large ones are called Jupiter Trojans (https://en.wikipedia.org/wiki/Jupiter_trojan) and can be up to 200km in diameter and more are being discovered all the time. The article above from universe today discusses this in the context of the University of Taiwan's work on Trojans from observations by the Pan-STARRS telescopes on Hawaii (https://en.wikipedia.org/wiki/Pan-STARRS).

This work has been going on for some time but is still in its early stages and there are also many satellites of the Ice Giants (https://en.wikipedia.org/wiki/Ice_giant) in orbit round the sun - Neptune (https://en.wikipedia.org/wiki/Neptune) and Uranus (https://en.wikipedia.org/wiki/Uranus). We know very little about these, just from Voyager flybys in the 1980s. Just identifying and counting the satellites is going to be a problem, we know even less about the other gas giant, Saturn (https://en.wikipedia.org/wiki/Saturn). These will probably have to be visited by their own probes, just as has been with Juno (https://en.wikipedia.org/wiki/Juno_(spacecraft)).

All this is just to show how little we know about the large outer planets. And if there is a ninth giant planet that makes another to add to the total.

[YesNo]

I thought only Jupiter had Trojans. Apparently even the Earth has some in its orbit. However, as I think about it, all those planets should have some if Jupiter has them.

Since Moffat's gravity theory made a prediction about gravity waves from the big bang which is different from what the Newton-Einstein theory would predict, I was looking at LIGO which showed the existence of gravitational waves last year. I am not sure what Moffat's prediction is, but at https://losc.ligo.org/about/ there is a tutorial about LIGO's recent findings with an interactive Jupyter notebook allowing you to play around with the data.

It occurred to me that all of these space missions should have something like this and perhaps they do. I just don't know about them.

[Dreamwoven]

Sorry, I didn't understand your point bout LIGO. I wondered why you had abandoned the Cosmology thread. Its still there, by the way, just no-one posted on it for quite some time.

There is an interesting post on cubesats: http://www.universetoday.com/82590/cubesat/.

[YesNo]

I'm glad to see that CubeSats are being developed. It opens up the exploration of space.

One CubeSat I would like to see is something designed to monitor changes of gravity as the CubeSat went further into space. The Pioneer 10 and 11 missions showed a potential slowing down of the space crafts due to stronger gravity but measurements were not accurate enough to determine whether that was the case or not.

I'll start posting what I find out from Moffat's book in the cosmology thread to help revive it. That might also be a good place for a LIGO/LISA discussion which are instruments that could falsify or validate Moffat's modified gravity theory.

[Dreamwoven]

Plans are being made for the establishment of a permanent colony on Mars. Read about it here: http://www.universetoday.com/46816/man-on-mars/

So far, these plans remain very vague and, presumably are likely to be postponed, perhaps even time and time again. This involves NASA but also private interests, and possibly the European Space Agency (http://www.esa.int/ESA).

You can read about the history of this idea at the above link.

[YesNo]

Solving problems leads to new technologies. So none of this dreaming about Mars is useless. However, we need to test all of it on the Moon first.

Some of the media interest around Mars has only one purpose--to get people willing to spend tax dollars on further space research. I don't think there is any real interest in going to Mars any time this century. If we have a market crash the resulting bearish social mood would make all of this irrelevant since we would not be able to afford it. However, even if we have a crash, I hope we would still be able to afford the LISA gravitational wave observatory.

While tracing links about gravitation, I found this video showing a feather and a bowling ball drop in a vacuum:


https://www.youtube.com/watch?v=E43-CfukEgs

[Dreamwoven]

http://www.universetoday.com/46816/astronaut-on-mars/

I had no idea that the Soviets had though so far ahead. Here are discussed many different stages of development from initial dependence on Earth to ultimate full independence on Mars.

[Dreamwoven]

I meant to add a comment on the preceding post. Very interesting on the effect of gravity on different objects, YesNo.

[Dreamwoven]

On second thoughts, I'm not sure what this post is saying. I thought that with no gravity nothing "falls", only if someone pushes it with their hand or something.

[YesNo]

There's gravity, but since it is in a vacuum there is no air resistance on the feathers to stop them from falling as fast as the heavier ball.

But the idea of "falling" is puzzling me at the moment. If the acceleration depends on mass shouldn't there be some difference between the ball and the feathers although tiny?

Also the idea of light bending when going past a massive object (gravitational lensing) does seem like it could be interpreted as mass giving the surrounding space a higher refractive index. Light also bends when passing through water. This refracting approach to gravitational lensing I got from Maya Benowitz in a comment made to a question about the existence of gravitons: https://www.quora.com/Quantum-Gravity-Why-hasnt-the-graviton-been-detected-yet

[prendrelemick]

From the top of my head I think it is the water's surface that refracts the light. It travels straight through the water. So I don't know if that model holds up.

I listened to a radio programme today from about 10 years ago on the Graviton, (by podcast) So much has moved on since then. The strange idea of the force of Gravity leaking into other dimensions (explaining why it is so weak ) was mentioned.


Just read your link - I agree that Force carrying particles are a difficult concept and would be even more improbable but for the example of the photon which is so active it can be measured. I don't get where the particle ends (eg the Higgs or the Graviton) and the 'field' begins. I suspect the model in my head is not imaginative enough.

[Dreamwoven]

OK, this post is from the journal Popular Astronomy (Sept/Oct 2016). NASA's Messenger Mission is not new, it has been circling Mercury since 2008, and collecting data. The most striking discovery is that Mercury's crust is predominantly made of graphite. A second probe, BepiColombo, is due to be launched in 2018, jointly by NASA and the Japanese Space Agency which will fill out the gaps that Messenger was unable to cover due to its orbit. See http://www.open.edu/openlearn/discovermercury.

I must confess I didn't know anything about the Messenger mission until reading this Popular Astronomy article.

[Danik 2016]

Plans are being made for the establishment of a permanent colony on Mars. Read about it here: http://www.universetoday.com/46816/man-on-mars/

So far, these plans remain very vague and, presumably are likely to be postponed, perhaps even time and time again. This involves NASA but also private interests, and possibly the European Space Agency (http://www.esa.int/ESA).

You can read about the history of this idea at the above link.
I don´t doubt that the aim of all this space interest is to create interplanetary human colonies. All this research and space expeditions are very expensive.
I wonder not only when they will be able to start this colonization but what kind of people they will send to space and what will be the survival conditions.

[YesNo]

From the top of my head I think it is the water's surface that refracts the light. It travels straight through the water. So I don't know if that model holds up.

I listened to a radio programme today from about 10 years ago on the Graviton, (by podcast) So much has moved on since then. The strange idea of the force of Gravity leaking into other dimensions (explaining why it is so weak ) was mentioned.


Just read your link - I agree that Force carrying particles are a difficult concept and would be even more improbable but for the example of the photon which is so active it can be measured. I don't get where the particle ends (eg the Higgs or the Graviton) and the 'field' begins. I suspect the model in my head is not imaginative enough.

The model in my head is all messed up with bits and pieces from the media. Today, I suspect there is no graviton although a few weeks ago I would have wondered if the graviton had mass just assuming it existed in the first place.

[Danik 2016]

Get your passports ready!

https://www.youtube.com/watch?v=6eirHoHsaQo
Obs. The last question is the one that matters.

[YesNo]

Boeing would be a company with resources to do some space research without relying on the taxpayer and governments. Also the ability to send out cubesats reduces the cost of research.

However, I don't see the point of sending human beings on these missions since machines can gather the data better than we can without needing biological and psychological support systems. We should soon have cars and planes that drive themselves. That might be the first step and something that can be done right on Earth: can we get acceptance of self-driving vehicles before the next recession which could slow down such technological change.

[Dreamwoven]

Your comment on Boeing was spot on, though perhaps it was discussed locally, as it is based in Chicago.
http://www.universetoday.com/131316/nasa-changing-course-mars-exploration/

There is a lot of interest in Mars, besides Boeing, Musk and other very rich private individuals, other countries are also getting into the race.

[Dreamwoven]

http://www.universetoday.com/131360/how-do-supernovae-fail/.

Interesting post, including much that is speculative.

[YesNo]

I didn't realize that it was possible for no remnant to remain during a supernova. Not leaving a remnant would be a more efficient way to distribute heavier elements throughout the universe.

The author indirectly emphasized the problem with black holes. In a fraction of a second the star is just gone at least in terms of anything taking up space. All the matter must have been converted into a warping of space-time based on a gravitational theory that has mathematical singularities in it. If I recalled Moffat correctly, even Einstein didn't like that part of his theory and was looking for a way to avoid those singularities because their presence in the theory suggests there is something wrong with the theory at those points.

[Dreamwoven]

http://www.universetoday.com/131378/new-dwarf-planet-joins-solar-system-family/

No name, just evidence that there is a previously unidentified planet in the Kuiper Belt.

[YesNo]

I wonder if this project to search for planets in the Kuiper Belt could be turned into a distributed computing project. Perhaps it already is. I have one of my old computers working on a distributed project at PrimeGrid that searches for primes in Sierpinski sequences.

[Dreamwoven]

I looked up the Sierpinski sequences and its those triangles that fit into each other. All beyond me that is. I only did maths to Ordinary Level General Certificate in school, and scraped a pass in it.

Back to astronomy, this post on http://www.universetoday.com/131403/exoplanet-huge-rings-intrigues/ looks fascinating.

[prendrelemick]

I looked up the Sierpinski sequences and its those triangles that fit into each other. All beyond me that is. I only did maths to Ordinary Level General Certificate in school, and scraped a pass in it.

Back to astronomy, this post on http://www.universetoday.com/131403/exoplanet-huge-rings-intrigues/ looks fascinating.

I notice it was discovered by the blink of a star. Yesterday I heard of a system being developed that will constantly monitor the whole of the sky, that's billions of stars all at once, and automatically detect any changes. These can then be checked out by astronomers. It is a simple and commonsensicle idea - let the computers do the boring meticulous stuff. If it all works properly, how much other stuff will be discovered.

So often the story of astronomical discovery starts with a lone astromoner sat on top of a mountain, just happening to notice something unusual.

[YesNo]

The computers should be doing the work, but there may be too much data to process and not enough funding for an institution to purchase the needed computing power to complete the tasks. And so one has distributed computing, a kind of crowd sourced research although it doesn't require knowing much about anything in particular to direct one's old computer to a project.

[Dreamwoven]

Back to astronomy, this post on http://www.universetoday.com/131403/exoplanet-huge-rings-intrigues/ looks fascinating.

I am trying to imagine a planet with such huge rings. There is an image of it in the Universe Today link above.


Giant Rings. The rings around J1407b are so large that we could see in the dusk from the earth when they were placed around the planet Saturn. The rings can be seen above the Old Leiden Observatory. Credit: M. Kenworthy / Leiden University

[YesNo]

It is nice to know that planetary rings can get larger than we might expect based on the rings around Saturn.

[Dreamwoven]

This Giant Exoplanet is orbiting round star some 420 light years from Earth.It was discovered in 2012 and Astronomers were puzzled by the unusual pattern of eclipses it produced, so it was studied in more detail, and the conclusion was that it must be caused by a planet with large rings around it, a giant version of Saturn:

For example, in 2015, the same team concluded that the ring system is one-hundred times larger and heavier than Saturn’s (and may be similarly sculpted by exomoons). And in their most recent study, they have shown that these giant rings may last for over 100,000 years, assuming they have a rare and unusual orbit around their planet.

In their previous work, Rieder and Kenworth determined that the ring system around J1407b consisted about 37 rings that extend to a distance of 0.6 AU (90 million km) from the planet. They also estimated that these rings are 100 times as massive as our Moon – 7342 trillion trillion metric tons. What’s more, while J1407b’s existence is yet to be confirmed, they were able to rule out the possibility of it having a circular orbit around the star.

The study continues...

[YesNo]

So they aren't some alien megastructure.

[Dreamwoven]

I think we have know that for some time, this explanation, dating from 2012 is much more convincing.

[desiresjab]

So often the story of astronomical discovery starts with a lone astromoner sat on top of a mountain, just happening to notice something unusual.

It sure does. And starts is the right word. Newton was desperate for the meticulous observations of Flamsteed so he could work on the moon's orbit. But Flamsteed was as jealous as Newton when it came to his work. Newton had the official influence to basically requisition Flamsteed's work. This crushed poor Flamsteed.

Gauss was professor of astronomy at Gottengen, where he lived in the tower one floor below the observatory. Classic. I don't know how much time Gauss had for observational astronomy. But he was busy inventing instruments for it and improving the ones already on hand with a mighty ingenuity, in addition to devising better ways to mathematically interpret astronomical data.

When the data is in the hands of a good mathematical physicist, a theory becomes possible. Figuring out those rings was awful smart. Gauss is the kind who could have done it. If we had him today he might just solve the dark energy/matter conunndrum, or make a great deal of progress on it. He is at the top of the class for mathematical astronomy of all time. Dang it, I want Gauss or Newton back. Statistically, though, we should have a mind as great as theirs working on these problems today with our gigantic world population participating, while all of that pair's discoveries came about with only Europe participating when it had a paltry population of a couple of hundred million.

Some of the missing pieces will be provided by observational astronomy. Insufficient observation at first supported the idea that the expansion of the universe was slowing down. Presumedly better observation supports the idea that it is speeding up. Even better observation that accounts for something unaccounted for in present observations could well leave Einstein's theory of gravitation intact. The fruits of refined observation are the most frequent cause of new astronomical theories, as far as I can tell, and the most frequent cause of refinement to the ones that already exist.

[Dreamwoven]

http://www.space.com/34380-bizarre-planet-giant-ring-system-in-reverse.html

This is worth reading!

[YesNo]

It seems that the reason they think the rings rotate in the opposite direction is because they are still there for us to observe. Otherwise they would have been thrown off during the early period of that system's existence.

[Dreamwoven]

It seems that the reason they think the rings rotate in the opposite direction is because they are still there for us to observe. Otherwise they would have been thrown off during the early period of that system's existence.

I don't follow you, YesNo. What would have been thrown off, the rings?

[YesNo]

I think that is what Rieder was saying when he was quoted. I may have misunderstood him. The ring system would be unstable if it moved in the same direction as the planet. If it is a ring, then it would have to go in the opposite direction we expect. Or perhaps it is not a ring but something else.

[desiresjab]

The ring moving in an opposite direction to the planet is intriguing. I never even thought of that before. What do the rings of Saturn do?

[Dreamwoven]

I think it is very rare that rings move in an opposite direction, the result of a catastrophic event:

How such a ring system could have come about is a mystery, as retrograde ring systems are quite uncommon. But Rieder and Kenworth have stated that they think it might be the result of a catastrophic event – such as a massive collision – that caused the rings (or the planet) to change the direction of their rotation. (http://www.universetoday.com/131403/exoplanet-huge-rings-intrigues/).

That's all we know at this point in time.

[Dreamwoven]

New Horizons is on its way deeper into the Kuiper Belt. It is heading for this odd-shaped object. Visit this space.com article for more details: http://www.space.com/34429-new-horizons-flyby-target-red-color.html

[Dreamwoven]

The object is very peculiar, as can be seen from the picture.

[Dreamwoven]

http://www.universetoday.com/131597/astronomers-think-know-rosettas-comet-came/

This is an interesting post, it plots the orbit of rosetta's comet, based on what we know of its movements while being tracked by the probe.

[YesNo]

The object is very peculiar, as can be seen from the picture.

We'll get to see how close the artist's rendering of the object is to the actual data coming back.

[Dreamwoven]

Yes, and this is how it was for New Horizons when it passed Pluto. All we knew is that it was a dot in the sky. We are still receiving data analyses from around the world, earthquakes, landslides, volcanic eruptions, its quite a remarkable catalogue. The same can happen again, with this much smaller object. it will indeed be exciting to see the results.

[Dreamwoven]

The moons of Mars - Deimos and Phobos - there is an explanation, worth reading: http://www.universetoday.com/14908/mars-moon-deimos1/

[Dreamwoven]

Moons are still being discovered around Uranus:

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 432 2016 October 23



POSSIBLE ADDITIONAL MOONS AROUND URANUS'S RINGS
University of Idaho

After re-examining data acquired by the Voyager 2 spacecraft,
astronomers have detected wavy patterns in two of Uranus's rings --
patterns that may be indicative of two undiscovered moons. Like the
other gas giants in the Solar System, Uranus has a ring system, though
it is not nearly as spectacular as the one around Saturn. And like
the other gas giants, Uranus has a lot of natural satellites -- 27 are
now known. New research suggests that that number might have to be
revised; data collected by Voyager 2 during its historic 1986 fly-by
hint at two undiscovered moons lurking near a pair of Uranus rings.
The suspected new moons reside in Alpha and Beta -- the 5th and 6th
rings. Voyager 2 found 10 moons when it visited the planet in 1986,
tripling the number of moons known to orbit the gas giant. The two
rings exhibit a series of wavy patterns consistent with the presence
of two tiny moons. The patterns may be wakes from small moonlets
orbiting outside those rings. Importantly, the observations are
consistent with how Uranus's other moons, such as Cordelia and
Ophelia, are exerting gravitational pressure on the dust, rocks, and
ice within the rings, herding the particles along a narrow formation.
If the now-postulated moons exist, they are quite dark and small,
measuring only 4 to 14 km across. That would make them smaller than
any other known moons orbiting the planet, which explains why Voyager
2 did not detect them directly. The researchers are now planning to
inspect Uranus with the Hubble telescope.

[YesNo]

Those possible, tiny moons around Uranus makes me wonder what criteria distinguishes a moon from one of the particles in a ring.

[Dreamwoven]

Perhaps the Hubble 'scope will be able to produce more info. But ultimately, rings and moons probably shade into one another?

[Dreamwoven]

Perhaps the Hubble 'scope will be able to produce more info. But ultimately, rings and moons probably shade into one another?

[Dreamwoven]

We are learning new things from Cassini's long visit at the moon, Titan, especially seasonal changes in it polar regions. See http://www.universetoday.com/131636/seasonal-change-titan-dynamic-business/

[YesNo]

It is good that missions last a while so we can observe such seasonal changes.

[Dreamwoven]

How many planets are there in our galaxy? A simple question but no simple answer. We have only recently realised just how many planets there are likely to be. See http://www.universetoday.com/30296/how-many-planets-are-in-the-galaxy/. We don't even know how many stars there are in our galaxy (The Milky Way). So any attempt to enumerate the planets in the galaxy is even more difficult. Of these, only a tiny fraction can be habitable.

[Dreamwoven]

Cassini has been at Saturn now since 2004, and is about to plunge between the rings of Saturn and investigate them.

http://www.space.com/34488-cassini-final-year-at-saturn-new-science.html

[Dreamwoven]

http://www.universetoday.com/131677/took-15-months-new-horizons-data-finally-downloaded/. This shows how long it takes to download information on the flyby of Pluto that New Horizons made. Well over a year in this case. New Horizons has continued deeper into the Kuiper Belt, making for a flyby of an object there that is mentioned in an earlier post on p.56.

[YesNo]

The article shows there were constraints the New Horizon designers were up against, but it doesn't say exactly what they were. For some reason, the craft could only have a limited power output of 2-10 watts. It could only have a low downlink rate of 1-4 kilobits per second. And it had limited memory since they will have to erase its hard drive so it could continue collecting data for an extended mission.

I would think some of these constraints could be relaxed in future missions with better technology.

[Dreamwoven]

Neptune and Uranus: the two outer ice giants of the family of solar planets. Each is described and discussed for what little we know of them:

http://www.universetoday.com/21581/neptune/

http://www.universetoday.com/18855/uranus/

[Dreamwoven]

Just about the only information we have on Neptune the large gas giant (and the furthest out of all the planets except the dwarf planet Pluto) is the flyby that Voyager 2 did way back in 1989. See preceding post for the link on Neptune. Neptune has 14 known moons and also five rings around it. But a further visit to this distant and little-known planet might be worth making, perhaps in conjunction with a visit to Uranus. Uranus has 13 "inner moons" and nine "irregular moons". It also has 13 distinct rings around it. Again only Voyager 2 has done a flyby, though there are tentative plans for further visit. It rotates on it's side which is unique among the giant planets.

[YesNo]

There is a graph in this link showing the axis of rotation of the various planets with some speculation on why we see such divergence: https://www.quora.com/Why-do-Venus-and-Uranus-rotate-clockwise-and-the-rest-of-the-planets-anticlockwise

Although Uranus rotates on its side, Venus rotates upside down. That is, it rotates in the opposite direction to Earth's rotation.

[Dreamwoven]

Yes,its speculation, much like Velikovsky speculated that Venus was a captured comet, but as with all such ideas we don't really know why.

[Dreamwoven]

http://www.space.com/16144-kuiper-belt-objects.html.

This discusses the main kuiper belt objects we know a bit about today, including the mysterious Planet 9.

[YesNo]

A link in that article led to one on the Oort cloud: http://www.space.com/16401-oort-cloud-the-outer-solar-system-s-icy-shell.html

It helped me see the difference between the Kuiper belt and the Oort cloud.

[Dreamwoven]

http://www.space.com/34555-how-many-planets-fit-inside-one-habitable-zone.html

An interesting article on habitable planets.

[YesNo]

It is interesting from the article that red dwarfs can last trillions of years and most of the stars are red dwarfs.

[Dreamwoven]

Not many people read the articles in the links. So I will just elaborate on the reasons why red dwarf stars are of interest in this context:

Van Laerhoven and her colleagues focused on K and M type stars, also known as red dwarfs. These stars are small, cold and about one-fifth the sun's mass and up to 50 times fainter. Red dwarfs constitute up to 70 percent of the stars in the universe, and NASA's Kepler spacecraft has discovered that at least half of these stars host rocky planets that are one-half to four times the mass of Earth.

Red dwarf planets are potentially key places to search for life, not just because there are so many of them, but also because of their incredible longevity. Unlike the sun, which will die in a few billion years, red dwarfs will take trillions of years to burn through their fuel, significantly longer than the age of the universe, which is about 13.8 billion years old. This longevity may give life ample time to develop on the planets that orbit these stars.

The habitable zones of red dwarfs fall close to these stars because of how cool they are — often closer than the distance at which Mercury orbits the sun. This closeness makes red dwarfs appealing to scientists hunting for habitable worlds, since planets in those habitable zones will cross in front of their star more often, making them easier to detect than planets that orbit farther away.

For the new research, the scientists carried out computer simulations involving a red dwarf about half the sun's mass, surrounded by a number of rocky planets with the same mass as Earth revolving around the star in circular orbits. These simulations each lasted up to 10 billion orbits of the innermost planet in each system. A planet at the inner edge of such a red dwarf's habitable zone would take only about one-fifth of an Earth-year to complete an orbit, Van Laerhoven said.

[YesNo]

My suspicion is that life doesn't need a lot of time, perhaps a few billion years. What is nice is that it should have a safe place to be for much longer. Of course the habitable zone changes over time. I suspect that is the same with dwarf stars.

Perhaps the next question I would have is how long can a planet with a red dwarf star expect to remain in its habitable zone?

[Dreamwoven]

The answer is in the second paragraph in my post:

Red dwarf planets are potentially key places to search for life, not just because there are so many of them, but also because of their incredible longevity. Unlike the sun, which will die in a few billion years, red dwarfs will take trillions of years to burn through their fuel, significantly longer than the age of the universe, which is about 13.8 billion years old. This longevity may give life ample time to develop on the planets that orbit these stars..

In short, longer than the universe has been in existence.

[Dreamwoven]

Water, water everywhere: even on a pure metal asteroid...

On Psyche, the largest asteroid in the solar system.

http://www.universetoday.com/131738/pure-metal-asteroid-found-with-mysterious-water-deposits/

[Dreamwoven]

The James Webb Space Telescope is ready for launching: http://www.space.com/34593-james-webb-space-telescope-complete-2018-launch.html. It is the new, much larger and more efficient space telescope since the Hubble Space Telescope. We should learn a lot from it once it is launched and ready to start work.

The telescope will be much more powerful than even Hubble for two main reasons, Mather said at the conference. First, it will be the biggest telescope mirror to fly in space. "You can see this beautiful, gold telescope is seven times the collecting area of the Hubble telescope," Mather said. And second, it is designed to collect infrared light, which Hubble is not very sensitive to.

Earth's atmosphere glows in the infrared, so such measurements can't be made from the ground. Hubble emits its own heat, which would obscure infrared readings. JWST will run close to absolute zero in temperature and rest at a point in space called the Lagrange Point 2, which is directly behind Earth from the sun's perspective. That way, Earth can shield the telescope from the sun's infrared emission, and the sun shield can protect the telescope from both bodies' heat.

The telescope's infrared view will pierce through obscuring cosmic dust to reveal the universe's first galaxies and spy on newly forming planetary systems. It also will be sensitive enough to analyze the atmospheres of exoplanets that pass in front of their stars, perhaps to search for signs of life, Mather said.

[Dreamwoven]

NASA has now got an asteroid warning system, with 5 days notice of any major threat to Earth. Sounds good. See: http://www.universetoday.com/131737/nasas-new-asteroid-alert-system-gives-5-whole-days-warning/:

Everyone knows it was a large asteroid striking Earth that led to the demise of the dinosaurs. But how many near misses were there? Modern humans have been around for about 225,000 years, so we must have come close to death by asteroid more than once in our time. We would have had no clue.

Of course, it’s the actual strikes that are cause for concern, not near misses. Efforts to predict asteroid strikes, and to catalogue asteroids that come close to Earth, have reached new levels. NASA’s newest tool in the fight against asteroids is called Scout. Scout is designed to detect asteroids approaching Earth, and it just passed an important test. Scout was able to give us 5 days notice of an approaching asteroid.

[Danik 2016]

I found this article interesting and the Max Planck Institute is a top research center in Germany.

"Searching for aliens who already know we're here
Astronomers suggest that future searches focus on that part of the sky in which distant observers can notice the yearly transit of Earth in front of the Sun"
http://www.astronomy.com/news/2016/03/searching-for-aliens-who-already-know-were-here

[Dreamwoven]

That link you sent me, Danik, was interesting. This quote I found particularly intriguing:

Not every star is equally well suited as a home of extraterrestrial life. The more massive a star, the shorter is its life span. Yet, a long stellar life is considered a prerequisite for the development of higher life forms. Therefore the researchers compiled a list of stars that are not only in the advantageous part of the sky, but also offer good chances of hosting evolved forms of life, that is, intelligent life. The researchers compiled a list of 82 nearby Sun-like stars that satisfy their criteria. This catalog can now serve as an immediate target list for SETI initiatives.

But astronomers are far from knowing every star in our Milky Way. The more distant a star, the dimmer its light appears. And the small, particularly long-lived stars are also particularly faint. In order to estimate how many stars in addition to the 82 nearby ones could reside in Earth’s transit zone, Heller and his Canadian colleague Ralph Pudritz projected the celestial sphere onto a model of the stellar density of our galaxy. The result: About 100,000 nearby stars could harbor planets with inhabitants who could have discovered us and who could be trying to contact us.

A part of these planets might be discovered with the PLATO mission of the European Space Agency, scheduled for 2024. René Heller from MPS is also involved in this mission. PLATO will use the transit method to find small planets, some of them possibly Earth-like, around bright stars.

[YesNo]

It makes sense to limit the search to those planets that have stars with a long life time, that are near-by and that if aliens existed on them they could observe Earth transiting the Sun. It am surprised the initial list is as small as 82. It might even encourage us to find ways to detect exoplanets on those stars that do not transit their suns.

[Dreamwoven]

http://www.space.com/34611-nasa-cassini-mission-saturn-rings-moons-solar-system-grand-finale.html

NASA's Cassini has been a busy spacecraft since it arrived at Saturn in 2004. Some of its key discoveries include seeing active water ice plumes at the moon Enceladus, watching strange storms develop in Saturn's atmosphere and (along with the Europe-led lander Huygens) discovering that the enigmatic moon Titan has lakes and seas just like Earth — but composed of methane and ethane, not water. However, all good things must come to an end and the mission is in its last year of operations. Low on fuel, it will make two daring orbital changes to creep closer to Saturn's rings and the planet before plunging into the planet itself. Here are just a handful of things left on Cassini's "to-do" list.

[Dreamwoven]

http://www.space.com/34590-saturn-rings-dwarf-planet-pieces.htmlhttp://www.space.com/34590-saturn-rings-dwarf-planet-pieces.html

The rings of Saturn, Neptune and Uranus are composed of pieces of Pluto-like dwarf planets that strayed too close to the giant worlds long ago, a new study suggests.

Astronomers think that thousands of Pluto-size bodies once dwelled in the Kuiper Belt — the ring of frigid objects beyond Neptune's orbit — shortly after the solar system formed. But things changed about 4 billion years ago, the idea goes: At that time, Jupiter, Saturn, Uranus and Neptune migrated a bit, stirring up both the Kuiper Belt and the main asteroid belt between Mars and Jupiter.

The resulting gravitational jostles sent many objects in these two realms careening toward the inner solar system, causing an era of increased cosmic impacts known as the Late Heavy Bombardment.

[YesNo]

The "Late Heavy Bombardment" implies there was an "Early Heavy Bombardment".

[Dreamwoven]

Yes, and there was an Early Heavy Bombardment.

For links see https://en.wikipedia.org/wiki/Late_Heavy_Bombardment
and
http://www.space.com/2299-insight-earths-early-bombardment.html

[Dreamwoven]

I also wonder about how the purported extinction of the dinosaurs was done. I wonder what kind of meteorite it was. How large and how widespread was the devastation it caused. All the seems very vague. See http://science.nationalgeographic.com/science/prehistoric-world/dinosaur-extinction

[Dreamwoven]

I also wonder about how the purported extinction of the dinosaurs was done. I wonder what kind of meteorite it was. How large and how widespread was the devastation it caused. All this remains very vague. What kind of an impact would it have been? How big was the object, a small exomoon, perhaps? The dinosaurs were wiped out in the seas, in the air (flying dinosaurs) and on land. See http://science.nationalgeographic.com/science/prehistoric-world/dinosaur-extinction. I also note that National Geographic include a gradualist theory as an alternative.

[YesNo]

If I remember what Niles Eldredge said in "Extinction and Evolution" correctly, the dinosaurs were becoming weak long before those meteorites hit the earth. Habitat was being lost because the climate was getting colder. This is not to say the volcanoes or meteorites, whatever deposited the layers containing iridium, did not help make the climate colder.

[Dreamwoven]

http://www.space.com/34629-nasa-fema-asteroid-impact-test.html

It's a scary scenario: an asteroid headed for Earth, just four years away from slamming into our home planet. It may be too short a span to plan an asteroid-deflection mission, but it's long enough to present very different challenges from those of a more typical crisis, like a hurricane or earthquake.

"It's not a matter of if, but when, we will deal with such a situation," Thomas Zurbuchen, NASA's Science Mission Directorate's new associate administrator, said in a statement. "But unlike any other time in our history, we now have the ability to respond to an impact threat through continued observations, predictions, response planning and mitigation."

I wonder how different scales of threats can be taken into account. How about an exomoon propelled into a crash with the Earth? Or is this just about asteroids?

[YesNo]

There is the movie "Melancholia" that dealt with the theme. In this case the planet Melancholia is much bigger than the earth and the earth will be the asteroid crashing into it. The assumption in the movie is that life existed no where else in the universe but on earth.

If the asteroid landed in deep water, the impact would probably be less than it if landed on land. However, if it landed on land this is one way that global warming might reverse since it should help cool off the climate. However, a good, hard global recession, even without an asteroid, would also stop global warming, at least, the part that we are causing.

There is a possibility that we are getting too close to the Venus zone and although still in the habitable zone where water is liquid, the atmosphere heats up too much. I suspect an array of satellites that reflected the sun's rays back out to space would help in this case.

[Danik 2016]

I found this article on the astronomic basis of "Melancholia". It is an old comment though (2011):
http://blogs.discovermagazine.com/badastronomy/2011/07/10/meloncholia/

[tailor STATELY]

Outlier body incursions reminds me of the sci-fi movie classic "When Worlds Collide" https://en.wikipedia.org/wiki/When_Worlds_Collide_(1951_film)

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY
Electronic News Bulletin No. 433 2016 November 6
CURIOUS TILT OF SUN'S AXIS ATTRIBUTED TO PLANET 9

Europlanet Media Centre


'Planet Nine' -- the undiscovered planet that was predicted by astronomers in January this year to exist at the edge of the Solar System -- has been held responsible for the tilt of the Sun's axis,according to a new study. The large and distant planet may be adding a wobble to the Solar System, giving the appearance that the Sun is tilted slightly. The argument goes that, because Planet Nine is so massive and has an orbit tilted with respect to the orbits of the other planets, the Solar System is slowly twisted out of alignment. All of the known planets' orbits lie close to a particular plane, roughly within a couple of degrees of each other. That plane,however, has a six-degree tilt with respect to the Sun, giving the impression that the Sun's axis of rotation is at that angle from the normal to the planetary orbits. Until now, no one had found a good explanation for that. The discovery of evidence that the Sun is orbited by an as-yet-unseen planet that is about 10 times the size of the Earth, in an orbit that is about 20 times farther from the Sun on average than Neptune's, changes the physics. Planet Nine, according to the calculations, appears to orbit in a plane at about 30 degrees from that of the other planets, influencing the orbits of a large popula-tion of objects in the Kuiper Belt, which is how astronomers came to suspect that a planet existed there in the first place.


The tilt of the Solar System's orbital plane has long been a puzzle to astronomers because of the way the planets formed: as a spinning cloud slowly collapsing first into a disc and then into objects orbiting the central star. Planet Nine's angular momentum is having an outsizedimpact on the Solar System on account of its location and size. A planet's angular momentum equals the mass of the object multiplied by its distance from the Sun, and represents the contribution that the planet makes to the overall system's spin. Because the other planets in the Solar System all orbit in practically the same plane, their angular momenta work to keep the whole disc spinning smoothly. Planet Nine's unusual orbit, however, adds a wobble to the system.Mathematically, given the hypothesized size and distance of Planet Nine, a six-degree tilt fits perfectly. The next question, then, is how did Planet Nine achieve its unusual orbit? Though that remains to be determined, it is suggested that the planet may have been ejected from the neighbourhood of the gas giants by Jupiter, or perhaps may have been influenced by the gravitational pull of other stellar bodies in the Solar System's extreme past. For now, astronomers will be searching the sky for signs of Planet Nine along the path that they predicted in January. That search may take some time.

We still have no idea what Planet 9's orbit is, so it could take a long time to locate it and to have some idea of what its orbit can be.

[YesNo]

If Planet 9 is not on the ecliptic it would not be where people are expecting it to be.

I don't think the planet in "Melancholia" is likely to exist, but the idea of looking to space for explanations for evolutionary changes on earth may be putting too much expectation on that source. The habitat/climate changes creating challenges for species and thereby allowing evolutionary changes to occur may have explanations that come from the earth itself, that is, volcanoes rather than meteorites.

[Dreamwoven]

http://www.universetoday.com/131818/next-cygnus-cargo-launch-to-space-station-switched-to-ula-atlas-v/

In a complete change of plans from less than three weeks ago, NASA has asked Orbital ATK to switch rockets and launch the firms next Cygnus commercial cargo freighter to the space station on the tried and true Atlas V rather than their own Antares rocket – which just successfully delivered another Cygnus to the orbiting outpost with a hefty stash of science and supplies.

The altered schedule “provides margin flexibility for the entire Antares workforce” Orbital ATK noted in a statement to Universe Today.

However, the change of events comes as something of a surprise following the spectacularly successful nighttime blastoff of Antares on Oct. 17 with the Cygnus OA-5 resupply ship from the Mid-Atlantic Regional Spaceport at NASA’s Wallops Flight Facility on Virginia’s picturesque Eastern shore – as I reported on from onsite.

[Danik 2016]

I was attracted by the image:
http://www.astronomy.com/news/2016/11/astronomers-look-a-spiral-galaxy-in-the-eye
"If it looks like spiral galaxy IC 2613 is staring at you, it’s not being rude: a collision with its nearest neighbor sent a wave crashing through the galaxy, which produced the strange eye-like structure."...

[YesNo]

I wonder how much damage colliding galaxies would have on the life of a planet in one of those galaxies?

[Dreamwoven]

You would have to have read Worlds in Collision to begin to understand that. Velikovsky comments on p. 305 under "The subjective interpretation of events and their authenticity".

[Dreamwoven]

http://www.universetoday.com/30537/what-are-magellanic-clouds/

WHAT ARE MAGELLANIC CLOUDS?

Article Updated: 8 Nov , 2016
by Matt Williams
Since ancient times, human beings have been staring at the night sky and been amazed by the celestial objects looking back at them. Whereas these objects were once thought to be divine in nature, and later mistaken for comets or other astrological phenomena, ongoing observation and improvements in instrumentation have led to these objects being identified for what they are.

For example, there are the Small and Large Magellanic Clouds, two large clouds of stars and gas that can be seen with the naked eye in the southern hemisphere. Located at a distance of 200,000 and 160,000 light years from the Milky Way Galaxy (respectively), the true nature of these objects has only been understand for about a century. And yet, these objects still have some mysteries that have yet to be solved.

The sheer size of phenomena and the huge distances involved are hard to grasp...

[Dreamwoven]

http://www.universetoday.com/131879/discovery-nearby-super-earth-5-times-mass/

Red dwarf stars have proven to be a treasure trove for exoplanet hunters in recent years. In addition to multiple exoplanets candidates being detected around stars like TRAPPIST-1, Gliese 581, Gliese 667C, and Kepler 296, there was also the ESO’s recent discovery of a planet orbiting within the habitable zone of our Sun’s closest neighbor – Proxima Centauri.

And it seems the trend is likely to continue, with the latest discovery comes from a team of European scientists. Using data from the ESO’s High Accuracy Radial velocity Planet Searcher (HARPS) and HARPS-N instruments, they detected an exoplanet candidate orbiting around GJ 536 – an M-class red dwarf star located about 32.7 light years (10.03 parsecs) from Earth.

According to their study, “A super-Earth Orbiting the Nearby M-dwarf GJ 536“, this planet is a super-Earth – a class of exoplanet that has between more than one, but less than 15, times the mass of Earth. In this case, the planet boasts a minimum of 5.36 ± 0.69 Earth masses, has an orbital period of 8.7076 ± 0.0025 days, and orbits its sun at a distance of 0.06661 AU.

I would only add to this that (a) circumstellar habitable zone (https://en.wikipedia.org/wiki/Circumstellar_habitable_zone) is far too broad a category to be of use in identifying planets that can be lived on by humans. Note that one restriction would be that the atmosphere is similar to that on Earth.

2.7 light years away is a major technological restriction to Faster the Light (FTS) travel. It means it would take that many years travelling at the speed of light to get there. There is as yet no technology to make travel at the speed of light possible. Even less possible is the idea of a warp drive (https://en.wikipedia.org/wiki/Warp_drive), such as we know from Star Trek.

We may be at the start of the space age, but we aren't going to the stars, not by a long chalk.

[YesNo]

I suspect every star has planets of some sort circling it. We just don't know about them. I agree that we are not going to send people to those planets, but we could communicate with them with a message delay of 2.7 years. I also suspect that life will form where ever it is possible for life to exist.

[Dreamwoven]

I suspect every star has planets of some sort circling it. We just don't know about them. I agree that we are not going to send people to those planets, but we could communicate with them with a message delay of 2.7 years. I also suspect that life will form where ever it is possible for life to exist.
Assuming there are humans there that are about our level of technology. I doubt very much there are...

[YesNo]

So far we haven't been able to find messages from anyone, but we have only started looking. We probably need to focus on those stars with exoplanets who could spot the Earth, if anyone there is looking, as one of their exoplanets. One of your previous posts mentioned doing something like this.

[Dreamwoven]

You can also use Lagrange Points to travel the solar system with minimum fuel requirements: http://www.universetoday.com/131953/interplanetary-transport-network/. Only slightly slower but much more efficient.

"But it turns out there’s another way you can travel from planet to planet in the Solar System, using a fraction of the energy you would use with the traditional Hohmann transfer, and that’s using Lagrange points.

We did a whole article on Lagrange points, but here’s a quick refresher. The Lagrange points are places in the Solar System where the gravity between two objects balances out in five places. There are five Lagrange points relating to the Earth and the Sun, and there are five Lagrange points relating to the Earth and the Moon. And there are points between the Sun and Jupiter, etc.


Three of these points are unstable. Imagine a boulder at the top of a mountain. It doesn’t take much energy to keep it in place, but it’s easy to knock it out of balance so it comes rolling down.

Now, imagine the whole Solar System with all these Lagrange points for all the objects gravitationally interacting with each other. As planets go around the Sun, these Lagrange points get close to each other and even overlap.

And if you time things right, you can ride along in one gravitationally balanced point, and the roll down the gravity hill into the grasp of a different planet. Hang out there for a little bit and then jump orbits to another planet.

In fact, you can use this technique to traverse the entire Solar System, from Mercury to Pluto and beyond, relying only on the interacting gravity of all these worlds to provide you with the velocity you need to make the journey."

[Dreamwoven]

http://www.universetoday.com/131970/pluto-subsurface-antifreeze-ocean/

"The evidence keeps growing for a large subsurface ocean at Pluto, which also provides clues how the iconic ‘heart’ of Pluto was formed.

We reported in early October that thermal models of Pluto’s interior and tectonic evidence suggest an ocean may exist beneath Pluto’s heart-shaped Sputnik Planitia. Now, new research on data from the New Horizons mission shows more indications of an ocean just below Pluto’s surface that consists of a slushy, viscous liquid, kept warm from Pluto’s interior and a hint of anti-freeze.

“As far as we can tell, there’s no tidal heating helping to keep the ocean liquid,” Francis Nimmo from UC Santa Cruz told Universe Today. He is the first author of a paper on the new findings published today in Nature. “The main heat source keeping the ocean liquid is radioactive decay in Pluto’s rocky interior, although it certainly helps if there is an ‘antifreeze’ present.”

Nimmo said he suspects the ocean is mostly water with ammonia acting as an antifreeze. This subsurface ocean is also bulging, similar to the ‘mascons’ on the Moon, putting stress on Pluto’s icy outer shell, causing fractures consistent with features seen in the New Horizons images.

Another paper also published in Nature today from James Keane at the University of Arizona, also shows how a bulging subsurface ocean made Pluto’s heart ‘heavy,’ reorienting Pluto on its axis, so that Pluto’s heart is always pointing away from the moon Charon."

[Dreamwoven]

http://www.universetoday.com/107598/what-is-the-kuiper-belt/

Future of the Kuiper Belt:
When he initially speculated about the existence of a belt of objects beyond Neptune, Kuiper indicated that such a belt probably did not exist anymore. Of course, subsequent discoveries have proven this to be wrong. But one thing that Kuiper was definitely right about was the idea that these Trans-Neptunian Objects won’t last forever. As Mike Brown explains:

We call it a belt, but it’s a very wide belt. It’s something like 45 degrees in extent across the sky – this big swath of material that’s just been churned and churned by Neptune. And these days, instead of making a bigger and bigger body, they’re just colliding and slowly grinding down into dust. If we come back in another hundred million years, there’ll be no Kuiper Belt left.
Given the potential for discovery, and what up-close examination could teach us about the early history of our Solar System, many scientists and astronomers look forward to the day when we can examine the Kuiper Belt in more detail. Here’s hoping that the New Horizons mission is just the beginning of future decades of research into this mysterious region!

We have many interesting articles here at Universe Today on the subject on the Outer Solar System and Trans-Neptunion Objects (TNOs).

And be sure to check out this article on the planet Eris, the latest dwarf planet and the largest TNO to be discovered.

And astronomers are expecting to discover two more large planets in our Solar System.

[YesNo]

It is interesting that we can detect Kuiper belts around other stars. I wonder how that was done. We can barely detect exoplanets around those stars.

Using the Lagrange points seems like a nice way to move around the solar system for research purposes. The craft should get energy somewhere, perhaps from the Sun so that it could keep sending back data continually. If it is made small enough like those cubesats, research about the solar system could be very inexpensive.

[Dreamwoven]

There may be a problem with that, as space telescopes are likely to be located at Lagrange points: Spitzer is likely to be located at one. Traffic congestion? Or perhaps not, I have no idea how large Lagrange points are. They of course move about as they are based on the movement of the planets...

[Dreamwoven]

EarthSky often has quite useful information on all things, not just space. See http://earthsky.org/space/what-makes-a-halo-around-the-moon

What makes a halo around the sun or moon? There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads.

These clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own particular halo, made by their own particular ice crystals, which are different from the ice crystals making the halo of the person standing next to you.

Why is it called a 22-degree halo? Because the ring has a radius of approximately 22° around the sun or moon.

[YesNo]

Come to think of it, clouds are mysterious. And they are not all alike which adds to the mystery.

[Dreamwoven]

http://dawn.jpl.nasa.gov/news/

The Dawn Mission has been exploring the dwarf planet Ceres for the lat 8 months. Now it will be going higher to get more views of it.

For more details on this study, see:
http://www.nasa.gov/feature/goddard/2016/ceres-cryo-volcano

This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past," Ruesch said.

For more details on this study, see:
http://www.nasa.gov/feature/goddard/2016/ceres-cryo-volcano

Ceres: Between a Rocky and Icy Place

While Ahuna Mons may have erupted liquid water in the past, Dawn has detected water in the present, as described in a study led by Jean-Philippe Combe of the Bear Fight Institute, Winthrop, Washington. Combe and colleagues used Dawn's visible and infrared mapping spectrometer (VIR) to detect probable water ice at Oxo Crater, a small, bright, sloped depression at mid-latitudes on Ceres.

Exposed water-ice is rare on Ceres, but the low density of Ceres, the impact-generated flows and the very existence of Ahuna Mons suggest that Ceres' crust does contain a significant component of water-ice. This is consistent with a study of Ceres' diverse geological features led by Harald Hiesinger of the Westfälische Wilhelms-Universität, Münster, Germany. The diversity of geological features on Ceres is further explored in a study led by Debra Buczkowski of the Johns Hopkins Applied Physics Laboratory, Laurel, Maryland.

Impact craters are clearly the most abundant geological feature on Ceres, and their different shapes help tell the intricate story of Ceres' past. Craters that are roughly polygonal -- that is, shapes bounded by straight lines -- hint that Ceres' crust is heavily fractured. In addition, several Cerean craters have patterns of visible fractures on their floors.

Some, like tiny Oxo, have terraces, while others, such as the large Urvara Crater (106 miles, 170 kilometers wide), have central peaks. There are craters with flow-like features, and craters that imprint on other craters, as well as chains of small craters. Bright areas are peppered across Ceres, with the most reflective ones in Occator Crater. Some crater shapes could indicate water-ice in the subsurface.

The dwarf planet's various crater forms are consistent with an outer shell for Ceres that is not purely ice or rock, but rather a mixture of both -- a conclusion reflected in other analyses. Scientists also calculated the ratio of various craters' depths to diameters, and found that some amount of crater relaxation must have occurred. Additionally, there are more craters in the northern hemisphere of Ceres than the south, where the large Urvara and Yalode craters are the dominant features.

"The uneven distribution of craters indicates that the crust is not uniform, and that Ceres has gone through a complex geological evolution," Hiesinger said.

Distribution of Surface Materials

What are the rocky materials in Ceres' crust? A study led by Eleonora Ammannito of the University of California, Los Angeles, finds that clay-forming minerals called phyllosilicates are all over Ceres. These phyllosilicates are rich in magnesium and also have some ammonium embedded in their crystalline structure. Their distribution throughout the dwarf planet's crust indicates Ceres' surface material has been altered by a global process involving water.

Although Ceres' phyllosilicates are uniform in their composition, there are marked differences in how abundant these materials are on the surface. For example, phyllosilicates are especially prevalent in the region around the smooth, "pancake"-like crater Kerwan (174 miles, 280 kilometers in diameter), and less so at Yalode Crater (162 miles, 260 kilometers in diameter), which has areas of both smooth and rugged terrain around it. Since Kerwan and Yalode are similar in size, this may mean that the composition of the material into which they impacted may be different. Craters Dantu and Haulani both formed recently in geologic time, but also seem to differ in composition.

"In comparing craters such as Dantu and Haulani, we find that their different material mixtures could extend beneath the surface for miles, or even tens of miles in the case of the larger Dantu," Ammannito said.

Looking Higher

Now in its extended mission, the Dawn spacecraft has delivered a wealth of images and other data from its current perch at 240 miles (385 kilometers) above Ceres' surface, which is closer to the dwarf planet than the International Space Station is to Earth. The spacecraft will be increasing its altitude at Ceres on Sept. 2, as scientists consider questions that can be examined from higher up.

Dawn's mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team."

[YesNo]

It does look like a volcano, but why only one such volcano on Ceres? Have they found out what those bright spots are?

[Dreamwoven]

It does look like a volcano, but why only one such volcano on Ceres? Have they found out what those bright spots are?

Yes, they found out what the bright spots were ages ago. Need to go back and look them up.

[Dreamwoven]

There is a wikipedia website on this: https://en.wikipedia.org/wiki/Bright_spots_on_Ceres

Mostly salt, it seems.

The Dawn probe will now go into perpetual orbit round Ceres even after its lost all its capabilities.

[Dreamwoven]

Sometimes Earth/Sky comes up with some interesting posts. Here is one on Cassini, the probe of Saturn: http://earthsky.org/space/saturn-spacecraft-prepares-to-ring-graze.

Lots to learn and discuss here.

[YesNo]

There is a wikipedia website on this: https://en.wikipedia.org/wiki/Bright_spots_on_Ceres

Mostly salt, it seems.

The Dawn probe will now go into perpetual orbit round Ceres even after its lost all its capabilities.

I checked that site, but it seems that they don't really know. They mentioned: "...it is material with a high level of reflection, and suggested ice and salt as possibilities." It still appears to be speculation.

[Dreamwoven]

Sometimes Earth/Sky comes up with some interesting posts. Here is one on Cassini, the probe of Saturn: http://earthsky.org/space/saturn-spacecraft-prepares-to-ring-graze.

Lots to learn and discuss here.


While it’s easy to feel nostalgic about the coming end of NASA’s wonderful Cassini mission to Saturn (source of so many incredible images), excitement is now building as the mission prepares to enter its grand finale year in 2017. NASA engineers have been pumping up the spacecraft’s orbit around Saturn this year to increase its tilt with respect to the planet’s equator and rings. On November 30, 2016, following a gravitational nudge from Saturn’s moon Titan, Cassini will go into an orbit that’ll send it just past the unexplored region at the outer edge of Saturn’s main rings. It’ll continue grazing the rings between November 30 and April 22, 2017, circling high over and under the poles of Saturn, diving past the rings every seven days, a total of 20 times. Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California, said:

We’re calling this phase of the mission Cassini’s Ring-Grazing Orbits, because we’ll be skimming past the outer edge of the rings.

And that’s only the beginning of Cassini’s grand finale in 2017.

First, though, why is the mission ending? Cassini has been in space for nearly 20 years. It launched from Earth in 1997 and has been touring the Saturn system – weaving among the planet’s rings and moons – since 2004. Its discoveries include a global ocean within Enceladus and liquid methane seas on Titan, but even those amazing discoveries pale next to the dramatic consciousness shift space fans have experienced over the years of this mission. Prior to Cassini, we had only glimpsed Saturn and its rings and moons. Now we see them, in all their intricate and profound beauty.

But, now, the Cassini spacecraft is running low on fuel. And so the mission must end, but not before it run through a year-long lists of “firsts” at Saturn. That’s following a series of “lasts,” by the way, related to Saturn’s moons, in 2016.

Simply put, before its end, Cassini has more science to do. For example, on many of the upcoming passes through the ringplane, Cassini’s instruments will attempt to sample ring particles and molecules of faint gases close to the rings, directly. Linda Spilker said:

… we have two instruments that can sample particles and gases as we cross the ringplane, so in a sense Cassini is also ‘grazing’ on the rings.

During the first two orbits, the spacecraft will pass directly through an extremely faint ring produced by tiny meteors striking the two small moons Janus and Epimetheus. Ring crossings in March and April will send the spacecraft through the dusty outer reaches of the F ring. Earl Maize, Cassini project manager at JPL, said:

Even though we’re flying closer to the F ring than we ever have, we’ll still be more than 4,850 miles (7,800 km) distant. There’s very little concern over dust hazard at that range.

The concern about dust will increase, though, after April, as Cassini executes the later phases of its grand finale. Ultimately, Cassini will pass as close as 1,012 miles (1,628 km) above Saturn’s cloudtops as it dives repeatedly through the narrow gap between Saturn and its rings.

The mission’s planned end will come on September 15, 2017, when the spacecraft will plunge into Saturn’s dense atmosphere.

For now, though, NASA says, some preparatory work remains:

To begin with, Cassini is scheduled to perform a brief burn of its main engine during the first super-close approach to the rings on December 4. This maneuver is important for fine-tuning the orbit and setting the correct course to enable the remainder of the mission…

To further prepare, Cassini will observe Saturn’s atmosphere during the ring-grazing phase of the mission to more precisely determine how far it extends above the planet. Scientists have observed Saturn’s outermost atmosphere to expand and contract slightly with the seasons since Cassini’s arrival. Given this variability, the forthcoming data will be important for helping mission engineers determine how close they can safely fly the spacecraft.

Bottom line: The Cassini spacecraft has been shifting its orbit throughout 2016, preparing for the mission’s grand finale in 2017. On November 30, it’ll begin a series of 20 orbits that fly high above and below Saturn’s poles, plunging just past the outer edge of the main rings.

[Dreamwoven]

I checked that site, but it seems that they don't really know. They mentioned: "...it is material with a high level of reflection, and suggested ice and salt as possibilities." It still appears to be speculation.

In that case, everything in space research is just speculation. At some point we have to accept that. There just is no 100 percent confirmation of much space exploration.

Nevertheless, I shall continue to observe.

Thi is from nature.com:
The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater1. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate1, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates2, 3, 4. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus5. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

[YesNo]

This is how I am reading the paragraph from nature:

When they say that the surface is "punctuated by areas of much higher albedo", we all know that since we can see the spots. It is just a fancy way to say there are bright areas on the dwarf planet. However, we wouldn't know about those spots without that mission going there in the first place.

The spectra data showing sodium carbonate (https://en.wikipedia.org/wiki/Sodium_carbonate) is new information. There's a mysterious "dark component" and then apparently spectra evidence for phyllosilicates, ammonium carbonate or ammonium chloride. So they have found out something about those spots.

The theory of how it got to the surface of Ceres is unknown, however, they suspect it came from within Ceres. That would require a heat source to move it to the surface. That heat source could come from the energy of an impact or Ceres' own internal temperature.

I guess I wouldn't expect them to know much more than what they can get from electromagnetic waves since they didn't land on Ceres and do some drilling into the dwarf planet.

[Dreamwoven]

The Fermi Paradox (https://en.wikipedia.org/wiki/Fermi_paradox) tries to understand the absence of extra-terrestrial intelligent life in the universe. See also http://www.universetoday.com/39804/fermi-paradox/.

We live in a big Universe, billions of light years across. There are hundreds of billions of galaxies, and each one contains hundreds of billions of stars. Life happened here on Earth, and with countless other stars out there, you would think life would have arisen somewhere else. And yet, we have no evidence there’s any other life in the Universe. If life is common in the Universe, where are all the aliens. This is the Fermi paradox.

The Fermi Paradox was first described by the physicist Enrico Fermi. Even if we aren’t visited by aliens, we should see some evidence for them out in the Universe, or be able to detect their radio transmissions. And yet, scientists haven’t found a single piece of technology that wasn’t created by humans, or found a life form doesn’t share a common heritage with all life on Earth. There hasn’t been a single intelligent signal detected from the Universe.

There is a thirty-minute broadcast you can listen to here (http://www.astronomycast.com/2007/02/episode-24the-fermi-paradox-where-are-all-the-aliens/).

There are several intriguing possibilities, including the fear of being discovered by ET intelligent life that is too underdeveloped to understand that they can destroy a civilisation which is quite capable of implementing Mutually-Assured Destruction (https://en.wikipedia.org/wiki/Mutual_assured_destruction).

A final thought. It is quite likely that we remain a poorly developed civilisation merely because we have barely begun to explore the universe. Even our own solar system is incompletely explored (I am thinking here of Planet 9 (https://en.wikipedia.org/wiki/Planet_Nine)). The Kuiper Belt (https://en.wikipedia.org/wiki/Kuiper_belt) has been preliminarily explored by New horizons (Pluto and one other object not yet visited) and the Oort Cloud (https://en.wikipedia.org/wiki/Oort_cloud) remains a vast unexplored area beyond the Belt. We of course also have telescopes located in space like WISE (https://en.wikipedia.org/wiki/Wide-field_Infrared_Survey_Explorer) and Spitzer (https://en.wikipedia.org/wiki/Spitzer_Space_Telescope), Hubble (https://en.wikipedia.org/wiki/Hubble_Space_Telescope), and James Webb Space Telescope (https://en.wikipedia.org/wiki/James_Webb_Space_Telescope).

There are a lot of ways communication with potential ET life this might happen. The links above should be read/listened to by anyone thinking of replying to this post, especially the 30 minute astronomycast link. Thank you.

[Dreamwoven]

http://www.universetoday.com/130230/far-asteroid-belt-sun/

Its been very quiet, I've not found anything I thought worthwhile to add to my astronomy thread in the last 11 days.

Structure and Composition:
The Asteroid Belt consists of several large bodies, along with millions of smaller size. The larger bodies, such as Ceres, Vesta, Pallas, and Hygiea, account for half of the belt’s total mass, with almost one-third accounted for by Ceres alone. Beyond that, over 200 asteroids that are larger than 100 km in diameter, and 0.7–1.7 million asteroids with a diameter of 1 km or more.

It total, the Asteroid Belt’s mass is estimated to be 2.8×1021 to 3.2×1021 kilograms – which is equivalent to about 4% of the Moon’s mass. While most asteroids are composed of rock, a small portion of them contain metls such as iron and nickel. The remaining asteroids are made up of a mix of these, along with carbon-rich materials. Some of the more distant asteroids tend to contain more ices and volatiles, which includes water ice.
Despite the impressive number of objects contained within the belt, the Main Belt’s asteroids are also spread over a very large volume of space. As a result, the average distance between objects is roughly 965,600 km (600,000 miles), meaning that the Main Belt consists largely of empty space. In fact, due to the low density of materials within the Belt, the odds of a probe running into an asteroid are now estimated at less than one in a billion.

While many spacecraft have been to the Asteroid Belt, most were passing through on their way to the outer Solar System. Only in recent years, with the Dawn mission, that the Asteroid Belt has been a focal point of scientific research. In the coming decades, we may find ourselves sending spaceships there to mine asteroids, harvest minerals and ices for use here on Earth.

We’ve written many articles about the Asteroid Belt here at Universe Today. Here’s What is the Asteroid Belt? (http://www.universetoday.com/32856/asteroid-belt/)
In the 18th century, observations made of all the known planets (Mercury, Venus, Earth, Mars, Jupiter and Saturn) led astronomers to discern a pattern in their orbits. Eventually, this led to the Titius–Bode law, which predicted the amount of space between the planets. In accordance with this law, there appeared to be a discernible gap between the orbits of Mars and Jupiter, and investigation into it led to a major discovery.

In addition to several larger objects being observed, astronomers began to notice countless smaller bodies also orbiting between Mars and Jupiter. This led to the creation of the term “asteroid”, as well as “Asteroid Belt” once it became clear just how many there were. Since that time, the term has entered common usage and become a mainstay of our astronomical models.
How Long Does it Take to get to the Asteroid Belt? (http://www.universetoday.com/130136/far-asteroid-belt-earth/), How Far is the Asteroid Belt from Earth? (http://www.universetoday.com/37532/where-do-asteroids-come-from/), Why Isn’t the Asteroid Belt a Planet? (http://www.universetoday.com/112464/why-isnt-the-asteroid-belt-a-planet/), and Why the Asteroid Belt Doesn’t Threaten Spacecraft. (http://www.universetoday.com/110276/why-the-asteroid-belt-doesnt-threaten-spacecraft/)

To learn more, check out NASA’s Lunar and Planetary Science Page on asteroids, and the Hubblesite’s News Releases about Asteroids.

Astronomy Cast also some interesting episodes about asteroids, like Episode 55: The Asteroid Belt and Episode 29: Asteroids Make Bad Neighbors.

[YesNo]

I am surprised to hear that the entire asteroid belt contains only about 4% of the Moon's mass. However, I don't see why we would mine material on these asteroids. There is the cost of getting there and getting back.

[Danik 2016]

I found this procedure of galaxi "feeding" interesting and it is related to the current theme of star composition:
http://www.astronomy.com/news/2016/12/super-galaxies-dont-become-cannibals-until-later-in-life

"Super-Galaxies Don’t Become Cannibals Until Later in Life
In their early years, the largest galaxies in the universe feed on recycled material from dead stars.
Before they turn to cannibalism, massive galaxies spend their infancy gobbling up recycled gas from earlier generations of star formation.

The Spiderweb Galaxy is actually more of a galaxy-in-progress. One day, it will be an enormous elliptical galaxy at the heart of a galactic cluster, but at the moment – technically, at a moment ten billion years away whose light is only just reaching us on Earth – it’s a group of about a dozen small proto-galaxies, slowly falling together and merging amid a vast halo of cold gas. At the center of that spiderweb of gas and merging galaxies sits a larger radio galaxy, which will one day form the core of the giant elliptical galaxy.

At 10 billion light-years away, the Spiderweb Galaxy offers astronomers a window into the formative years of the largest galaxies in the universe. It turns out that the birth of a super-galaxy is a more complex process than previously thought."

http://www.astronomy.com/news/2016/12/super-galaxies-dont-become-cannibals-until-later-in-life

[YesNo]

I have noticed a lot of "feeding" metaphors used to describe what happens in galaxies. Before there was the idea of a black hole at the center of our galaxy which was supposed to eat some dust cloud a while back (it didn't happen) and now there are cannibals on an even larger frame.

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4


Here is the latest round-up of news from the Society for Popular
Astronomy.


"MARS ICE DEPOSIT HOLDS AS MUCH WATER AS LAKE SUPERIOR
NASA/Jet Propulsion Laboratory

Researchers using the Mars Reconnaissance Orbiter have discovered
that, frozen beneath a region of cracked and pitted plains on Mars,
lies about as much water as is contained in Lake Superior, largest of
the North-American Great Lakes. Scientists examined part of Mars'
Utopia Planitia region, in the mid-northern latitudes, with the
orbiter's ground-penetrating Shallow Radar (SHARAD) instrument.
Utopia Planitia is a basin with a diameter of about 3,300 km,
resulting from a major impact early in Mars' history and subsequently
filled. Analyses of the radar data from more than 600 overhead passes
reveal an ice deposit more extensive in area than the British Isles.
The deposit ranges in thickness from about 80 to 170 metres, with a
composition that is 50 to 85% water ice, mixed with dust or larger
rocky particles. At the latitude of the deposit -- about 45 degrees
-- ice cannot persist on the surface of Mars today; it sublimes into
water vapour in the thin, dry atmosphere. The Utopia deposit is
shielded from the atmosphere by a covering of soil, estimated to be
about 1 to 10 metres thick. Mars today, with an axial tilt of 25
degrees, accumulates large amounts of water ice at the poles. In
cycles lasting about 120,000 years, the tilt varies to nearly twice
that much, warming the poles and driving ice to middle latitudes.
Climate modelling and previous findings of buried mid-latitude ice
indicate that frozen water accumulates away from the poles during the
long high-tilt periods.

The newly surveyed ice deposit spans latitudes from 39 to 49 degrees
within the plains. It represents less than 1% of all known water
ice on Mars, but it more than doubles the volume of thick, buried
ice sheets known in the northern plains. Ice deposits close to the
surface are being considered as a resource for potential astronauts.
The deposit described here is probably more accessible than most water
ice on Mars, because it is at a relatively low latitude and it lies in
a flat, smooth area where landing a spacecraft would be less hazardous
than in some of the other areas where there is buried ice. The
Utopian water is all frozen now. If there were a melted layer --
which would be significant for the possibility of life on Mars -- it
would have been evident in the radar scans. However, some melting can
not be ruled out during different climate conditions when the planet's
axis was more tilted."

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

NEW FAMILY OF STARS IN CORE OF MILKY WAY
Liverpool John Moores University

Astronomers have discovered a new family of stars in the core of our
Milky Way galaxy, providing new insights into the early stages of the
Galaxy's formation. The discovery, made from the Sloan Digital Sky
Survey, has shed new light on the origins of globular clusters. One
of the projects of this collaboration is APOGEE (the Apache Point
Observatory Galactic Evolution Experiment), which collects infrared
data for hundreds of thousands of stars in the Milky Way. It was
through observing stars in the infrared towards the Galactic Centre
that the discovery was made of a new population of stars, the like
of which had been seen before only inside globular clusters. That
intriguing new family of stars could possibly have belonged to
globular clusters that were destroyed during the violent initial
formation of the Galactic centre, in which case there would have been
about 10 times more globular clusters in the Milky Way in its early
stages than there are today. That could mean that a substantial
fraction of the old stars inhabiting the inner parts of the Galaxy
today may have been formed initially in globular clusters that were
later destroyed.

The finding helps astronomers address fascinating questions such as
what is the nature of the stars in the inner regions of the Milky Way,
how globular clusters formed, and what role they played in the
formation of the early Milky Way -- and by extension the formation of
other galaxies. The centre of the Milky Way is poorly understood,
because it is blocked from view by intervening dust. Observing in the
infrared, which is less absorbed by dust than visible light, APOGEE
can see the centre of the Galaxy better than other methods. From the
observations the chemical compositions of thousands of stars could be
determined; among them was a considerable number of stars that
differed from the bulk of those in the inner regions of the Galaxy,
owing to their very high abundance of nitrogen. While not certain, it
is suspected that those stars resulted from the destruction of
globular clusters. They could also be the by-products of the first
episodes of star formation taking place at the beginning of the
Galaxy's history.

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4



NEW FAMILY OF STARS IN CORE OF MILKY WAY
Liverpool John Moores University

Astronomers have discovered a new family of stars in the core of our
Milky Way galaxy, providing new insights into the early stages of the
Galaxy's formation. The discovery, made from the Sloan Digital Sky
Survey, has shed new light on the origins of globular clusters. One
of the projects of this collaboration is APOGEE (the Apache Point
Observatory Galactic Evolution Experiment), which collects infrared
data for hundreds of thousands of stars in the Milky Way. It was
through observing stars in the infrared towards the Galactic Centre
that the discovery was made of a new population of stars, the like
of which had been seen before only inside globular clusters. That
intriguing new family of stars could possibly have belonged to
globular clusters that were destroyed during the violent initial
formation of the Galactic centre, in which case there would have been
about 10 times more globular clusters in the Milky Way in its early
stages than there are today. That could mean that a substantial
fraction of the old stars inhabiting the inner parts of the Galaxy
today may have been formed initially in globular clusters that were
later destroyed.

The finding helps astronomers address fascinating questions such as
what is the nature of the stars in the inner regions of the Milky Way,
how globular clusters formed, and what role they played in the
formation of the early Milky Way -- and by extension the formation of
other galaxies. The centre of the Milky Way is poorly understood,
because it is blocked from view by intervening dust. Observing in the
infrared, which is less absorbed by dust than visible light, APOGEE
can see the centre of the Galaxy better than other methods. From the
observations the chemical compositions of thousands of stars could be
determined; among them was a considerable number of stars that
differed from the bulk of those in the inner regions of the Galaxy,
owing to their very high abundance of nitrogen. While not certain, it
is suspected that those stars resulted from the destruction of
globular clusters. They could also be the by-products of the first
episodes of star formation taking place at the beginning of the
Galaxy's history.

[YesNo]

If they found more stars at the center of the galaxy that would suggest to me that they have identified new sources of mass. This would reduce the need for dark matter or a black hole at the center of our galaxy.

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

EXTREMELY FAINT SATELLITE GALAXY OF MILKY WAY
National Astronomical Observatory of Japan

Astronomers have found an extremely faint dwarf satellite galaxy of
the Milky Way. The satellite lies in the direction of the constellation
Virgo and has accordingly been named Virgo I. At an absolute
magnitude of -0.8 in the optical waveband, it may well be the faintest
satellite galaxy yet found. Its discovery suggests the presence of a
large number of yet-undetected dwarf satellites in the halo of the
Milky Way, and provides important insights into galaxy formation
through hierarchical assembly of dark matter. Currently, some 50
satellite galaxies of the Milky Way have been identified. About 40
of them are faint and diffuse and belong to the category of 'dwarf
spheroidal galaxies'. Many recently discovered dwarf galaxies,
especially those found in systematic photometric surveys such as the
Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey (DES), are
very faint, with absolute luminosities in the optical waveband less
than -8 magnitude. They are called 'ultra-faint dwarf galaxies'.
However, previous searches made use of telescopes of apertures 2.5 to
4 metres, so only satellites relatively close to the Sun or those with
brighter magnitudes were identified.

The combination of the large aperture of the 8.2-m Subaru Telescope
and the large field of view of the Hyper Suprime Cam (HSC) instrument
is very powerful for this study. It enables an efficient search to
be made for very faint dwarf satellites over large areas of the sky.
The first step in searching for a new dwarf galaxy is to identify an
over-density of stars in the sky, using photometric data. Next is to
assess that the over-dense appearance is not due to line-of-sight or
accidental juxtapositions of unrelated dense fields, but is really a
stellar system. The standard method for doing that is to look for a
characteristic distribution of stars in the colour-magnitude diagram
(analogous to the Hertzsprung-Russell diagram). Stars in a general
field show no particular patterns in this diagram. The team examined
the early data of the Subaru Strategic Survey with HSC and found an
apparent over-density of stars in Virgo with very high statistical
significance, showing a characteristic pattern of an ancient stellar
system in the colour-magnitude diagram. It is indeed a galaxy,
because it is spatially extended with a radius of 124 light-years --
larger than a globular cluster with comparable luminosity. The
faintest dwarf satellites identified so far are Segue I, discovered by
SDSS (-1.5 mag) and Cetus II in DES (0.0 mag). Cetus II is yet to be
confirmed, as it is too compact as a galaxy, so Virgo I may turn out
to be the faintest one so far discovered. It lies at a distance of
280,000 light-years from the Sun, and such a remote galaxy with such a
low luminosity has not been identified in previous surveys. It is
beyond the reach of SDSS, which has previously surveyed the same area
in the direction of the constellation Virgo.

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

DO EXTREMELY REDDENED QUASARS EXTINGUISH STAR FORMATION?
University of California - Riverside

Galaxies formed and grew thousands of millions of years ago by
accumulating gas from their surroundings, or colliding and merging
with other young galaxies. Those early stages of galaxy assembly are
believed to be accompanied by episodes of rapid star formation, known
as starbursts, and rapid growth of a single super-massive black hole
in each galactic centre. A popular paradigm for such evolution has
the black holes growing mostly in obscurity, buried deep within the
dusty gas in the centres of the galaxies. Those are rich star-forming
galaxies, until a blowout of gas and dust (outflow) extinguishes the
star formation and halts further growth in the black holes. At that
stage there is revealed the luminous material in the immediate
vicinity of the rapidly growing black hole in the galactic nucleus.
Such objects are known as quasars. Quasars can eject material at
high speeds, possibly helping to drive the blowout and regulate star
formation in their host galaxies. However, many aspects of that
evolutionary scheme are not understood. Quasars that are partially
obscured by dust, which reddens their light in a way that is similar
to the apparent reddening of the Sun as it approaches sunset on
Earth, might provide windows into galactic evolution during the brief
transition stage when the starburst is winding down and the visibly
luminous quasar is first being revealed in the galactic centre. New
research describes the discovery of the new population of extremely
red quasars detected in the Baryon Oscillation Sky Survey (BOSS) of
the Sloan Digital Sky Survey (SDSS).

The main goal of that study was to determine the size of the
population of extremely red quasars, and to characterize its basic
properties in comparison with the much larger population of quasars
in the BOSS--SDSS survey overall. The extremely red quasars were
selected for study because of their extreme colour, but the analysis
reveal a number of peculiar properties consistent with a unique and
possibly young evolutionary stage. In particular, they have an
exceptionally high incidence of powerful quasar-driven outflows that
could be involved in galaxy-wide blowouts of gas and dust. Overall,
the gaseous environments around the black holes appear to be more
extended and more energetic than the environments of normal quasars,
which might occur at specific times when young gas-rich host galaxies
are dumping prodigious amounts of matter into the central black holes,
creating an extreme variety of quasars. More work is needed now to
examine the population of extremely red quasars further and understand
its relationship to the general phenomenon of quasars and, perhaps, to
a particularly violent phase of quasar-galaxy evolution.

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4

LARGE NUMBER OF DWARF GALAXES FOUND IN EARLY UNIVERSE
University of California at Riverside

A team of researchers has found a large population of distant dwarf
galaxies that could reveal important details about a productive period
of star formation in the Universe thousands of millions of years ago.
The findings build on a growing body of knowledge about dwarf
galaxies, the smallest and dimmest galaxies in the Universe. Though
relatively diminutive, they are very important for understanding the
history of the Universe. It is believed that dwarf galaxies played a
significant role during the 're-ionization era', in transforming the
early Universe from being dark, neutral and opaque to one that is
bright, ionized and transparent. Despite their importance, distant
dwarf galaxies remain elusive, because they are extremely faint and
mostly beyond the reach of even the best telescopes, so the current
picture of the early Universe is incomplete. However, gravitational
lensing, which was predicted by Einstein from his general theory of
relativity long before it was actually observed, causes a massive
object such as a galaxy located along the line of sight to another
distant object to act as a natural lens, concentrating the light
coming from the background source. The phenomenon sometimes allows
us to discover distant dwarf galaxies that would otherwise be too
faint to detect.

As a proof of concept, in 2014 the team targeted one cluster of
galaxies that produces the gravitational-lensing effect and got a
glimpse of what appeared to be a large population of distant dwarf
galaxies. The team used the Wide-Field Camera 3 on the Hubble Space
Telescope to take deep images of three clusters of galaxies. They
found the large population of distant dwarf galaxies from a time when
the Universe was between two and six thousand million years old.
That cosmic time is critical, as it was the most productive time
for star formation in the Universe. In addition, the team obtained
spectroscopic data from the Multi-Object Spectrograph for Infrared
Exploration (MOSFIRE) on the Keck telescope, and confirmed that the
galaxies belonged to that important cosmic period. Those dwarf
galaxies are 10 to 100 times fainter than galaxies that had been
previously observed from that period of time. Though faint, the
galaxies are far more numerous than their brighter counterparts.

The study demonstrates that the number of dwarf galaxies changed
during that important time period in such a way that they were
even more abundant at earlier times. In fact, the researchers had
unveiled a population of dwarf galaxies that were the most numerous
galaxies in the Universe during those times. Despite their individual
faintness, the dwarf galaxies produced more than half of all ultra-
violet light during that era. As ultraviolet radiation is produced
by young hot stars, dwarf galaxies evidently hosted a significant
fraction of newly-formed stars at that period of cosmic time. Those
results suggest that dwarf galaxies played a prominent role in the
re-ionization era; they will be among the primary targets of the next
generation of telescopes, particularly the James Webb Space Telescope,
scheduled to be launched in 2018.

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 435 2016 December 4


MARS PROBE RETURNS FIRST PICTURES
BBC Online

Europe's and Russia's new satellite at Mars has sent back its first
images of the planet. The Trace Gas Orbiter (TGO) arrived on October
19, putting itself into a highly eccentric elliptical parking orbit,
which must be circularized over the coming year before the mission
can become fully operational. Scientists have, however, taken the
opportunity of some close passes to the planet in recent days to check
out the TGO's instrumentation. They are delighted at the quality of
the pictures returned from the camera system, CaSSIS (the Colour and
Stereo Surface Imaging System). Two of TGO's sensors - NOMAD and ACS
- also came through their early tests. Those are the sensors that
will make a detailed inventory of Mars' atmospheric gases. In
particular, they will go after the components that constitute less
than 1% of the planet's air -- chemical species such as methane, water
vapour, nitrogen dioxide, and sulphur dioxide. Methane is the main
focus. From previous measurements, its concentration seems to be low
and sporadic in nature, but the mere fact that it is detected at all
is really fascinating.

Methane (CH4) is the simplest organic molecule, and ought to be
destroyed easily in the harsh Martian environment, so its persistence
-- and the occasional spikes in its signal -- indicate a source that
replenishes the gas. The speculation is that it could be coming from
microbial life somewhere on the planet. It will be CaSSIS's job to
look for possible topographical forms on the surface that might tie
into methane sources. A fourth instrument, FREND, will sense hydrogen
in the near-surface. Those data can be used as proxy for the presence
of water or hydrated minerals. That again is information that could
yield answers to the methane question. TGO was the unspoken success
on the day that ESA's Schiaparelli lander crashed onto Mars. The
surface probe had been dropped off by TGO and was making its ill-fated
descent just as the satellite took up its parking orbit, and the
successful insertion went almost unnoticed in the fuss over
Schiaparelli. TGO is the first phase in a joint venture at Mars that
Europe is undertaking with Russia. The second step in the project,
known as ExoMars, is to put a robot rover on the planet in 2021. It
needs a lot of money from the European side to go forward, however --
just over 400m Euros. Research ministers from ESA member states are
meeting this week in Switzerland to try to resolve the budget problem.

[YesNo]

It is interesting that a probe can do more than get evidence from the electromagnetic spectrum, but can actually collect samples from the atmosphere. I wonder why the rover on the planet is not doing that already.

I had thought they would have detected evidence for microbial life on Mars by now.

[Dreamwoven]

Sorry for the long delay in my reply!

I doubt whether a rover on the surface could undertake atmospheric measurements, you clearly need a satellite for that. This is just the first phase. As stated in their wiki post: https://en.wikipedia.org/wiki/ExoMars the second step will need to be done, to put a robot rover on the planet in 2021:

TGO is the first phase in a joint venture at Mars that
Europe is undertaking with Russia. The second step in the project,
known as ExoMars, is to put a robot rover on the planet in 2021. It
needs a lot of money from the European side to go forward, however --
just over 400m Euros. Research ministers from ESA member states are
meeting this week in Switzerland to try to resolve the budget problem.

After this they need to do phase 2 Exomars (Europe and Russia combined) in 2012, if it is approved.

It must be difficult co-ordinating all this. Especially as Russia has not done this before (no space projects since the USSR). See the wikipedia post on this: https://en.wikipedia.org/wiki/ExoMars. NASA has done all the Mars exploration up till now using land-based rovers.

I think we need to spend some time to catch up on this. Its been 3 months since your reply, YesNo.

[YesNo]

It is good to see someone besides NASA doing this research. There should be permanent robotic bases on Mars and the Moon if for no other reason than to test and improve the technology.

[Dreamwoven]

Today I got my first issue of the Swedish equivelent of Popular Astronomy: Populär Astronomi. I will be interested to compare it with the British version. It only comes out quarterly, though, not bi-monthly.

[Dreamwoven]

Today I was in Bollnäs Library and reading the journals. Popular Astronomy (http://www.popastro.com/index.php) had an article on the space photometry revolution (http://www.popastro.com/popularastronomy/issue.php?id_popast=36) in which Hubble (http://hubblesite.org) played a pioneering part. Now, new generations of space telescopes are becoming more and more prominent. The Spitzer infra-red space telescope (https://en.wikipedia.org/wiki/Spitzer_Space_Telescope) is just one of a whole range of space telescopes deploying or under development.

This will radically improve our ability to study so-called goldylocks planets (https://science.nasa.gov/science-news/science-at-nasa/2012/29mar_goldilocks/) around other stars. There is an article on this in the current issue of The Swedish magazine Popular Science (https://en.wikipedia.org/wiki/Popular_science#Notable_English-language_popularizers_of_science) (Populär Vetenskap) has one on the search for life in other worlds. Some 3,000 worlds have been found that are classed as Goldylocks Worlds, possible harbouring life in some form or another.

Much of this - for now all of it - is speculation, but it will be interesting to see whether any life (e.g. micro-organisms) will be found on other exo-planets going around "near-by" stars.

[YesNo]

It looks like we still haven't found a Goldilocks planet yet, but "transit spectroscopy" sounds promising if a Goldilocks planet is ever discovered especially nearby.

[Dreamwoven]

I think it is quite likely that we will find a goldilocks planet relatively soon. But I doubt if it will have more than unicellular "life". Most people immediately jump to the conclusion that life means advanced animal life. Thats the danger with generalised definitions like "goldilocks planet". It rises expectations far too high.

[YesNo]

I would be happy just to find unicellular life, however, I don't know how we would be able to detect it. If there is an advanced civilization that we can talk to that would convince us that life existed on those exoplanets.

[Dreamwoven]

Well, there is no evidence that there is an advanced civilisation on one of the moons of Saturn, the one which has methane seas on it. See this Wikipedia item of the moons of Saturn: https://en.wikipedia.org/wiki/Moons_of_Saturn.

I think it is pretty well established that there is no civilisation anywhere that is at all near to Earth, as far as we can tell.

Perhaps if NASA is planning a more detailed investigation of Mars they might come up with something. I believe water is found underground om Mars. See http://motherboard.vice.com/blog/mars-might-have-a-soggy-underground, though only traces, no seas.

[YesNo]

In the solar system, the most I would expect to see are microorganisms. At least we can get to those objects. But further out, I don't know how we would tell there are microorganisms on an exoplanet.

[Dreamwoven]

No, I agree.

[Dreamwoven]

Earth Trojans are asteroids that circle the sun in the vicinity of the Earth-Sun Lagrangian Points. see https://en.wikipedia.org/wiki/Earth_trojan.

See also this article on Earth-Sun's only know Earth Trojan: http://news.nationalgeographic.com/news/2011/07/1107128-trojan-asteroid-earth-planet-orbit-nasa-space-science/.

See also this article on Earth Trojans: http://planetfacts.org/trojan/

Make sure you read the links if anything is unclear.

[Dreamwoven]

Earth Trojans:
An Earth trojan is an asteroid that orbits the Sun in the vicinity of the Earth–Sun Lagrangian points L4 (leading 60°) and L5 (trailing 60°), thus having an orbit similar to Earth's. Only one Earth trojan has so far been discovered. The name trojan was first used in 1906 for the Jupiter trojans, the asteroids that were observed near the Lagrangian points of Jupiter's orbit.

[Dreamwoven]

Tiny companion will remain tied to our planet for at least ten thousand years, experts predict.

A tiny space rock that's partially tethered to Earth by a gravitational leash is our planet's first known Trojan asteroid, astronomers say.

[Dreamwoven]

A Trojan, in Astronomy, is a minor planet or moon that shares an orbit with a larger planet or satellite but does not collide with the larger planet because while it orbits, it stays safely in what is called as the Lagrangian points. In theory, there are also Trojan planets that may reside at Trojan points.

Lagrangian points are five spots in any space where the gravitational pull of two relatively massive bodies, as in the case of a Sun and a planet are balanced out, making it possible for smaller bodies like moons, minor planets and asteroids to remain fixed, in essence, with respect to the planet. The smaller objects still move but they are locked into a synchronized orbit due to the gravities exerted by the two large bodies. Thus, collisions are avoided. However, only two of the five Lagrangian points located around 60 degrees of the planet at any point (L4 and L5) are stable and smaller objects and bodies tend to collect in the area. L1, L2 and L3, on the other hand are unstable, causing rapid object displacement.

The most popular Trojans in astronomy are those discovered around Neptune. They are so numerous that they are believed to be more than the asteroid count in the Asteroid Belt between the inner and outer planets. There are currently 6 known Trojans in the L4 point of the Neptune’s orbit. There are few identified Trojans because they are very faint as not only are they small, they are also too far from the Earth and the Sun. Studying Trojans help astronomers in understanding how planets and the planetary systems, such as the Solar system evolved.

The three links together can be understood by combining them into the three posts as I have done here.

I think this is fascinating...

[YesNo]

On the one hand the discovery of this 300 meter trojan in the Earth's orbit in 2010 makes me think that we do not know much about the solar system. On the other, this object is only 300 meters in diameter which isn't very large.

[Dreamwoven]

Earth is only a minor planet, the bigger ones like Jupiter and Saturn have more.

[Dreamwoven]

The possibility of water on Mars' surface has been questioned. See the post below: http://www.space.com/35071-mars-dark-streaks-liquid-water-debate.html

[Dreamwoven]

More on Trojans: EarthSky report that a probe will search for more. See http://earthsky.org/space/osiris-rex-feb-2017-search-earth-trojan-asteroids

[YesNo]

I can see how more massive planets would have more trojans.

[Dreamwoven]

Thats what I said. What about the other questions?

It easier if you quote the post you are addressing...

[YesNo]

I am just agree with you. I am glad to see the OSIRIS_REx spacecraft can get a closer look.

[desiresjab]

More on Trojans: EarthSky report that a probe will search for more. See http://earthsky.org/space/osiris-rex-feb-2017-search-earth-trojan-asteroids

So Lagrangian points 1,2 and 3, all in one straight line with sun and earth, are barely stable, and points 4 and 5, 60° ahead of us and behind us in our orbital path, are highly stable. We have a cool one and a hot one a million miles on either side of us directly in line with us and the sun which are barely stable. Not much use is projected for point 3 on the far side of the sun, where the legendary (fictional) planet X is supposed to be. If there were a planet our size there, they would probably reason that any planet in our position would have an unstable orbit, so there is probably not one where we are. Ahem!

At least points 1 and 2 are stable enough for space equipment to reside. At point 2 no special cooling equipment is required, which simplifies a mission. Points 4 and 5 are great prospects for some asteroids we can mine or for settlement. Any news of those locations will be of keen interest to any who read this thread.

Which brings me to a question: If these are the famous Lagrangian points and the nearest are a million miles away, what are these stable points that Arthur C. Clarke was responsible for predicting where we now keep many satellites parked? Are these too Lagrangian points, but points from a separate deal between the earth and moon? These points are only about 22000--26000 miles from earth, I believe. These points seem to represent "gravity wells," as well, just like their bigger brothers, if that is even what they are. Do you know anything about that?

[desiresjab]

I answered my own question. They seem mechanically separate phenomena, though they could be confused as related. An object in obit around earth at a Clarke point travels around us at the same rate we rotate on our own axis. The net result is it stays in one place above a point on the equator through night and day with us. If Clarke points and Lagrangian points have a relationship, I do not see it. I know almost no mathematics of celestial mechanics, so there could easily be a relationship I do not see.

[Dreamwoven]

Hmm, my understanding of Lagrangian Points is that they exist between all planets, suns, and any space object that has its own gravity. I don't know anything about Clarke Points as mathematical phenomena, though.

[Dreamwoven]

Hmm, my understanding of Lagrangian Points is that they exist between all planets, suns, and any space object that has its own gravity.

I can't find anything helpful on Clarke points. Only this website in Wikipedia but in Swedish on Clarke Points: https://sv.wikipedia.org/wiki/Clarke_Point

[Dreamwoven]

http://www.universetoday.com/132413/colonize-saturns-moons/

Extracts from this post. read the whole article at the above link.

Welcome back to our series on Colonizing the Solar System! Today, we take a look at the largest of Saturn’s Moons – Titan, Rhea, Iapetus, Dione, Tethys, Enceladus, and Mimas.

From the 17th century onward, astronomers made some profound discoveries around the planet Saturn, which they believed was the most distant planet of the Solar System at the time. Christiaan Huygens and Giovanni Domenico Cassini were the first, spotting the largest moons of Saturn – Titan, Tethys, Dione, Rhea and Iapetus. More discoveries followed; and today, what we recognized as the Saturn system includes 62 confirmed satellites.

What we know of this system has grown considerably in recent decades, thanks to missions like Voyager and Cassini. And with this knowledge has come multiple proposals that claim how Saturn’s moons should someday be colonized. In addition to boasting the only body other than Earth to have a dense atmosphere, there are also abundant resources in this system that could be harnessed.

Much like the idea of colonizing the Moon, Mars, the moons of Jupiter, and other bodies in the Solar System, the idea of establishing colonies on Saturn’s moons has been explored extensively in science fiction. At the same time, scientific proposals have been made that emphasize how colonies would benefit humanity, allowing us to mount missions deeper into space and ushering in an age of abundance!

On March 9th, 2006, NASA’s Cassini space probe found possible evidence of liquid water on Enceladus, which was confirmed by NASA in 2014. According to data derived from the probe, this water emerges from jets around Enceladus’ southern pole, and is no more than tens of meters below the surface in certain locations. This would would make collecting water considerably easier than on a moon like Europa, where the ice sheet is several km thick.

Data obtained by Cassini also pointed towards the presence of volatile and organic molecules. And Enceladus also has a higher density than many of Saturn’s moons, which indicates that it has a larger average silicate core. All of these resources would prove very useful for the sake of constructing a colony and providing basic operations.

In October of 2012, Elon Musk unveiled his concept for an Mars Colonial Transporter (MCT), which was central to his long-term goal of colonizing Mars. At the time, Musk stated that the first unmanned flight of the Mars transport spacecraft would take place in 2022, followed by the first manned MCT mission departing in 2024.

In September 2016, during the 2016 International Astronautical Congress, Musk revealed further details of his plan, which included the design for an Interplanetary Transport System (ITS) and estimated costs. This system, which was originally intended to transport settlers to Mars, had evolved in its role to transport human beings to more distant locations in the Solar System – which could include the Jovian and Cronian moons.

[YesNo]

As far as colonizing those places go, it seems more useful to put satellites around them or send probes to their surfaces. They could be our eyes. I suspect mining could have some value if there is something there that we need on Earth.

It was interesting reading about setting up a greenhouse effect on Mars to warm it up so it would be more habitable for us to get there, however, controlling the greenhouse effect on any planet including our own might be useful for those planets already in the habitable zone. If we can terraform Mars we should be able to terraform Venus and have the technology to make sure Earth stays terraformed when it gets closer to the Sun. I think the best solution would be a set of satellites that reflected away radiation from the Sun or focused it depending on the degree of greenhouse effect we wanted to achieve. We should experiment with the Moon first.

[desiresjab]

Hmm, my understanding of Lagrangian Points is that they exist between all planets, suns, and any space object that has its own gravity.

I can't find anything helpful on Clarke points. Only this website in Wikipedia but in Swedish on Clarke Points: https://sv.wikipedia.org/wiki/Clarke_Point

Absolutely Lagrange points exist around all massive objects. Here is the other point that Clarke first suggested. They are known as geostationary orbits. They are a different phenomenon from the Lagrange points because they stay with a single point on our equator as that point moves through night and day, while the Lagrange points are stationary (except for moving with us in orbit) and all points of our equator pass beneath them (assuming, that is, that they are aligned with our equator, which I do not know for sure).

As I think about it, I am starting to believe the Lagrange points would not be oriented above our equator at all, but about the Great Circle (a mapping term) which would be our equator without tilt. It is an interesting question which I have to find out though I am now pretty sure the Lagrange points would care nothing at all for our equator, any more than they would align themselves with some of the highly eccentric planetary orbits found in our solar system. Our home pair are a million miles away. No, they would not care about our little equator. Sometimes you answer your own questions.

[Dreamwoven]

So Lagrange Points would be the best places to locate space telescopes, like Hubble and Spitzer. Makes sense!


Absolutely Lagrange points exist around all massive objects. Here is the other point that Clarke first suggested. They are known as geostationary orbits. They are a different phenomenon from the Lagrange points because they stay with a single point on our equator as that point moves through night and day, while the Lagrange points are stationary (except for moving with us in orbit) and all points of our equator pass beneath them (assuming, that is, that they are aligned with our equator, which I do not know for sure).

As I think about it, I am starting to believe the Lagrange points would not be oriented above our equator at all, but about the Great Circle (a mapping term) which would be our equator without tilt. It is an interesting question which I have to find out though I am now pretty sure the Lagrange points would care nothing at all for our equator, any more than they would align themselves with some of the highly eccentric planetary orbits found in our solar system. Our home pair are a million miles away. No, they would not care about our little equator. Sometimes you answer your own questions.

[Danik 2016]

About the "warm Neptun", a new planet:
"A pioneering new study uncovering the 'primitive atmosphere' surrounding a distant world could provide a pivotal breakthrough in the search to how planets form and develop in far-flung galaxies.

[/I]The atmosphere of the distant “warm Neptune” HAT-P-26b, illustrated here, is unexpectedly primitive, composed primarily of hydrogen and helium. By combining observations from NASA’s Hubble and Spitzer space telescopes, researchers determined that, unlike Neptune and Uranus, the exoplanet has relatively low metallicity, an indication of the how rich the planet is in all elements heavier than hydrogen and helium.[/I]
Credit: NASA/GSFC

At:https://www.sciencedaily.com/releases/2017/05/170511141951.htm

[YesNo]

That article gives a nice description of "metallicity". I didn't know so much could be known about an exoplanet's atmosphere.

[Danik 2016]

Neither did I, Yes/No. One of the things that fascinates me is that these new planets that are discovered are a challenge to the astronomers theories. It´s not so long ago we knew about a solar system that now seems so modest in the light of the new discoveries. Now we know even about the atmosphere of very distant planet.

[Dreamwoven]

What’s on the Surface of Venus?
by Fraser Cain
We’re always talking about Mars here on the Guide to Space. And with good reason. Mars is awesome, and there’s a fleet of spacecraft orbiting, probing and crawling around the surface of Mars.

The Red Planet is the focus of so much of our attention because it’s reasonably close and offers humanity a viable place for a second home. Well, not exactly viable, but with the right technology and techniques, we might be able to make a sustainable civilization there.

We have the surface of Mars mapped in great detail, and we know what it looks like from the surface.

But there’s another planet we need to keep in mind: Venus. It’s bigger, and closer than Mars. And sure, it’s a hellish deathscape that would kill you in moments if you ever set foot on it, but it’s still pretty interesting and mysterious to visit.

Would it surprise you to know that many spacecraft have actually made it down to the surface of Venus, and photographed the place from the ground? It was an amazing feat of Soviet engineering, and there are some new technologies in the works that might help us get back, and explore it longer.


Venera 10 image of Venusian surface (1975). 174-degree raw 6-bit logarithmically encoded telemetry seen above. Linearized and aperture corrected view in center, including data from a second 124-degree panorama. Bottom image had missing portions in-painted with Bertalmio's algorithm.

Today, let’s talk about the Soviet Venera program. The first time humanity saw Venus from its surface.

Back in the 60s, in the height of the cold war, the Americans and the Soviets were racing to be the first to explore the Solar System. First satellite to orbit Earth (Soviets), first human to orbit Earth (Soviets), first flyby and landing on the Moon (Soviets), first flyby of Mars (Americans), first flyby of Venus (Americans), etc.

The Soviets set their sights on putting a lander down on the surface of Venus. But as we know, this planet has some unique challenges. Every place on the entire planet measures the same 462 degrees C (or 864 F).

Furthermore, the atmospheric pressure on the surface of Venus is 90 times greater than Earth. Being down at the bottom of that column of atmosphere is the same as being beneath a kilometer of ocean on Earth. Remember those submarine movies where they dive too deep and get crushed like a soda can?

Finally, it rains sulphuric acid. I mean, that’s really irritating.

Needless to say, figuring this out took the Soviets a few tries.

Venera 1
The Venera 1 spacecraft

Their first attempts to even flyby Venus was Venera 1, on February 4, 1961. But it failed to even escape Earth orbit. This was followed by Venera 2, launched on November 12, 1965, but it went off course just after launch.

Venera 3 blasted off on November 16, 1965, and was intended to land on the surface of Venus. The Soviets lost communication with the spacecraft, but it’s believed it did actually crash land on Venus. So I guess that was the first successful “landing” on Venus?

Before I continue, I’d like to talk a little bit about landing on planets. As we’ve discussed in the past, landing on Mars is really really hard. The atmosphere is thick enough that spacecraft will burn up if you aim directly for the surface, but it’s not thick enough to let you use parachutes to gently land on the surface.

Landing on the surface of Venus on the other hand, is super easy. The atmosphere is so thick that you can use parachutes no problem. If you can get on target and deploy a parachute capable of handling the terrible environment, your soft landing is pretty much assured. Surviving down there is another story, but we’ll get to that.

Venera 4 came next, launched on June 12, 1967. The Soviet scientists had few clues about what the surface of Venus was actually like. They didn’t know the atmospheric pressure, guessing it might be a little higher pressure than Earth, or maybe it was hundreds of times our pressure. It was tested with high temperatures, and brutal deceleration. They thought they’d built this thing plenty tough.


The Venera 4 spacecraft. Venera spacecraft 3 to 6 were similar. Image supplied by NASA

Venera 4 arrived at Venus on October 18, 1967, and tried to survive a landing. Temperatures on its heat shield were clocked at 11,000 C, and it experienced 300 Gs of deceleration.

The initial temperature 52 km was a nice 33C, but then as it descended down towards the surface, temperatures increased to 262 C. And then, they lost contact with the probe, killed dead by the horrible temperature.

We can assume it landed, though, and for the first time, scientists caught a glimpse of just how bad it is down there on the surface of Venus.

Venera 5 was launched on January 5, 1969, and was built tougher, learning from the lessons of Venera 4. It also made it into Venus’ atmosphere, returned some interested science about the planet and then died before it reached the surface.

Venera 6 followed, same deal. Built tougher, died in the atmosphere, returned some useful science.

Venera 7 was built with a full understanding of how bad it was down there on Venus. It launched on August 17, 1970, and arrived in December. It’s believed that the parachutes on the spacecraft only partially deployed, allowing it to descend more quickly through the Venusian atmosphere than originally planned. It smacked into the surface going about 16.5 m/s, but amazingly, it survived, and continued to send back a weak signal to Earth for about 23 minutes.

For the first time ever, a spacecraft had made it down to the surface of Venus and communicated its status. I’m sure it was just 23 minutes of robotic screaming, but still, progress. Scientists got their first accurate measurement of the temperatures, and pressure down there.

Bottom line, humans could never survive on the surface of Venus.

Venera 8 blasted off for Venus on March 17, 1972, and the Soviet engineers built it to survive the descent and landing as long as possible. It made it through the atmosphere, landed on the surface, and returned data for about 50 minutes. It didn’t have a camera, but it did have a light sensor, which told scientists being on Venus was kind of like Earth on an overcast day. Enough light to take pictures… next time.


The Venera 9 spacecraft. Image supplied by NASA

For their next missions, the Soviets went back to the drawing board and built entirely new landing craft. Built big, heavy and tough, designed to get to the surface of Venus and survive long enough to send back data and pictures.

Venera 9 was launched on June 8, 1975. It survived the atmospheric descent and landed on the surface of Venus. The lander was built like a liquid cooled reverse insulated pressure vessel, using circulating fluid to keep the electronics cooled as long as possible. In this case, that was 53 minutes. Venera 9 measured clouds of acid, bromine and other toxic chemicals, and sent back grainy black and white television pictures from the surface of Venus.

In fact, these were the first pictures ever taken from the surface of another planet.

Images from Venera 9 (top) and Venera 10 (bottom). Public Domain Images, courtesy of NASA/National Space Science Data Center.
Images from Venera 9 (top) and Venera 10 (bottom). Public Domain Images, courtesy of NASA/National Space Science Data Center.

Venera 10 lasted for 65 minutes and took pictures of the surface with one camera. The lens cap on a second camera didn’t release. The spacecraft saw lava rocks with layers of other rocks in between. Similar environments that you might see here on Earth.

Venera 11 was launched on September 9, 1975 and lasted for 95 minutes on the surface of Venus. In addition to confirming the horrible environment discovered by the other landers, Venera 11 detected lightning strikes in the vicinity. It was equipped with a color camera, but again, the lens cap failed to deploy for it or the black and white camera. So it failed to send any pictures home.

Venera 12 was launched on September 14, 1978, and made it down to the surface of Venus. It lasted 110 minutes and returned detailed information about the chemical composition of the atmosphere. Unfortunately, both its camera lens caps failed to deploy, so no pictures were returned. And pictures are what we really care about, right?

Venera 13 was built on the same tougher, beefier design, and was blasted off to Venus on October 30, 1981, and this one was a tremendous success. It landed on Venus and survived for 127 minutes. It took pictures of its surroundings using two cameras peering through quartz windows, and saw a landscape of bedrock. It used spring-loaded arms to test out how compressible the soil was.


The surface of Venus as captured by Soviet Venera 13 lander in March of 1982. NASA/courtesy of nasaimages.org

Venera 14 was identical and launched just 5 days after Venera 13. It also landed and survived for 57 minutes. Unfortunately, its experiment to test the compressibility of the soil was a botch because one of its lens caps landed right under its spring-loaded arm. But apart from that, it sent back color pictures of the hellish landscape.

And with that, the Soviet Venus landing program ended. And since then, no additional spacecraft have ever returned to the surface of Venus.

It’s one thing for a lander to make it to the surface of Venus, last a few minutes and then die from the horrible environment. What we really want is some kind of rover, like Curiosity, which would last on the surface of Venus for weeks, months or even years and do more science.

And computers don’t like this kind of heat. Go ahead, put your computer in the oven and set it to 850. Oh, your oven doesn’t go to 850, that’s fine, because it would be insane. Seriously, don’t do that, it would be bad.

Engineers at NASA’s Glenn Research Center have developed a new kind of electrical circuitry that might be able to handle those kinds of temperatures. Their new circuits were tested in the Glenn Extreme Environments Rig, which can simulate the surface of Venus. It can mimic the temperature, pressure and even the chemistry of Venus’ atmosphere.


A before (top) and after (bottom) image of the electronics after being tested in the Glenn Extreme Environments Rig. Credit: NASA

The circuitry, originally designed for hot jet engines, lasted for 521 hours, functioning perfectly. If all goes well, future Venus rovers could be developed to survive on the surface of Venus without needing the complex and short lived cooling systems.

This discovery might unleash a whole new era of exploration of Venus, to confirm once and for all that it really does suck.

While the Soviets had a tough time with Mars, they really nailed it with Venus. You can see how they built and launched spacecraft after spacecraft, sticking with this challenge until they got the pictures and data they were looking for. I really think this series is one of the triumphs of robotic space exploration, and I look forward to future mission concepts to pick up where the Soviets left off.

Are you excited about the prospects of exploring Venus with rovers? Let me know your thoughts in the comments

[Dreamwoven]

Forgot to include the link to the above post: https://www.universetoday.com/134338/whats-surface-venus/.

[Danik 2016]

Phantastic link, DW! Personally I am still sceptic about men ever being able to live on Venus on account of the heat of the planet. You see I live in a city where the spring/summer temperatures reach 36°.

[Dreamwoven]

NASA's exploration strategy has undergone a quiet revolution, with the emphasis shifting to exploring the planets in more detail. Dawn is in permanent orbit round Ceres, so it has become an artificial moon of that planet. See https://www.universetoday.com/135585/dawn-gets-right-sun-ceres-takes-video/. Jupiter has another going round, called Juno. Saturn with its many moons and rings has a probe, Cassini, making dives through the rings and taking images of Saturn's moons. It will be crashed into Saturn when its finished its tasks. Mars has several land-based exploration vehicles on that planet.

There is growing interest in finding life on our nearest neighbour exoplanets in their so-called "habitable zone". I don't think they will find advanced forms of life th4re but single-cell life, perhaps.

Universetoday.com is now my main source of information. Its an excellent website for info on exploring the universe.

[Danik 2016]

Yes, I noticed the shift too. These programs all must be very expensive. It seems that they are very anxious to unload humans somewhere else. I see a certain analogy with the discovery of America.
I´ll have a look at universe today. There seem to be two or three serious astronomic sites.

[Dreamwoven]

Yes, they are expensive, but of special interest is a return visit to Pluto, way out in the Kuiper Belt. The first visit was a flyby, just to get some info on this planet. The results were so interesting that NASA is planning to return, hopefully for a longer visit.

[Danik 2016]

Interesting news, DW, I´ll have a look later on if there are any news about it.

[YesNo]

I didn't realize there were so many Venera missions. Putting a rover on Venus does provide a challenge that is worth solving. There should be a way to terraform Venus and Mars and keep Earth from becoming like Venus when it gets closer to the Sun although I know we aren't likely to find a way to do all of that for thousands of years.

[Danik 2016]

This is just a joke but I found it interesting because some of these concerns might become serious in a not so far future:

https://blog.nols.edu/2017/04/01/new-course-space-travel-april-fools

Some images of Pluto and its surroundings:

http://astro.wsu.edu/worthey/astro/html/lec-pluto.html

[Danik 2016]

"One of the most prominent features on Pluto is the informally named Cthulhu Regio, also called "the whale," which stretches across 1,900 miles (3,000 km). Cthulhu Regio is pockmarked with craters, which suggests it is billions of years old — much older than the craterless, young "heart" it borders. Scientists have said the dark region's reddish coloring might come from tholins, which are complex hydrocarbons.

To further investigate how the whale got its coloring, Yasuhito Sekine, an associate professor at the University of Tokyo, conducted heating experiments on organic molecules, like formaldehyde, that would have been present on the newly forming Pluto soon after the formation of the solar system. Sekine found that he could produce the same dark, reddish color after heating solutions above 122 degrees Fahrenheit (50 degrees Celsius) for several months. "
http://www.space.com/36853-pluto-whale-charon-impact.html

[Dreamwoven]

More moons are being discovered in the Kuiper Belt. This one is 600 miles across, see EarthSky:

http://earthsky.org/space/hubble-moon-dwarf-planet-2007-or10

[Dreamwoven]

EarthSky and Space.com are the two websites I have been following for some years now, https://www.universetoday.com is more recent, I get updates most days.

[Dreamwoven]

A long article on how difficult it would be to send an unmanned mission at 20% of the speed of light to Alpha Centauri, the nearest star to the solar system.

http://earthsky.org/space/alpha-centauri-travel-time

[Danik 2016]

A stunning article, DW! I fancy science will to advance a lot, creating time and space patterns that are unfathomable to us at present. In US sci-fi films the scientifical battles interrupt an every day course but doesn´t change it. The heroes come back and find families and friends as they have left them.
But imagine a situation where you pass a weekend on a nearby star and come back finding everything has changed and your kids have become old people?

[Dreamwoven]

that would be truly horrific!

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY
Electronic News Bulletin No. 445 2017 May 21

THIRD-LARGEST DWARF PLANET HAS MOON

NASA/Goddard Space Flight Center


The combined power of three space observatories, including the Hubble Space Telescope, has helped astronomers discover a moon orbiting the third-largest dwarf planet, catalogued as 2007 OR10.The pair resides in the frigid outskirts of the Solar System called the Kuiper Belt, a realm of icy debris left over from the system's formation 4.6 billion years ago. With this discovery,most of the known dwarf planets in the Kuiper Belt larger than 600 miles across have companions. Those bodies provide insight into how moons formed in the young Solar System. The discovery of satellites around all of the known large dwarf planets (except for Sedna) means that, when those bodies formed, a very long time ago, collisions must have been more frequent, and that is a constraint on the formation models. If there were frequent collisions, then it was quite easy to form satellites. The objects most likely slammed into one another more often because they inhabited a crowded region. But the speed of the colliding objects could not have been too fast or too slow, according to the astronomers. If the impact velocity were too great, the smash-up would have created lots of debris that could have escaped from the system; if too slow, the collision would have produced only an impact crater.


The team discovered the moon in archival images of 2007 OR10 taken by Hubble's Wide-Field Camera 3. Observations taken of the dwarf planet by the Kepler space telescope first tipped off the astronomers to the possibility of a moon circling it. Keple rrevealed that 2007 OR10 has a slow rotation period of 45 hours.Typical rotation periods for Kuiper-Belt Objects are under 24 hours. The team looked in the Hubble archive because the slower rotation period could have been caused by the gravitational effect of a moon. The initial investigator missed the moon in the Hubble images because it is very faint. The astronomers observed the moon in two separate Hubble observations spaced ayear apart. The images show that the moon is gravitationally bound to 2007 OR10 because it moves with the dwarf planet, as seen against a background of stars. However, the two observations did not provide enough information for the astronomers to determine an orbit. They calculated the diameters of both objects on the basis of observations in far-infrared light by the Herschel Space Observatory, which measured their thermal emission. The dwarf planet is about 950 miles across, and its moon is estimated to be 150--250 miles in diameter. 2007 OR10,like Pluto, follows an eccentric orbit, and is currently three times farther from the Sun than Pluto is. 2007 OR10 is a member of the exclusive club of 'dwarf planets', of which there are nine. Of those bodies, only Pluto and Eris are larger.

[Dreamwoven]

A FAR-FLUNG MEMBER OF THE SOLAR SYSTEM

National Radio Astronomy Observatory


Using the Atacama Large Millimeter/submillimeter Array (ALMA),astronomers have obtained extraordinary details about a recently discovered far-flung member of the Solar System, the planetary body 2014 UZ224, informally known as DeeDee. At about three times the current distance of Pluto from the Sun, DeeDee is the second-most-distant-known trans-Neptunian object (TNO) with a confirmed orbit, surpassed only by the dwarf planet Eris.Astronomers estimate that there are tens of thousands of such icy bodies in the outer Solar System beyond the orbit of Neptune.The new ALMA data reveal, for the first time, that DeeDee is roughly 635 kilometres across, or about two-thirds the diameter of Ceres, the largest member of the asteroid belt. At that size, DeeDee should have enough mass to be spherical, the criterion necessary for astronomers to consider it to be a dwarf planet,though it has yet to receive that official designation.Currently, DeeDee is about 92 astronomical units (AU) from the Sun. It takes DeeDee more than 1,100 years to complete one orbit; light from DeeDee takes nearly 13 hours to reach the Earth.


The object was discovered with the 4-metre Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile as part of ongoing observations for the 'Dark Energy Survey', that seeks to understand the accelerating expansion of the Universe. The Dark Energy Survey produces vast numbers of astronomical images, which give astronomers the opportunity to search also for distant Solar-System objects. The initial search, which includes nearly 15,000 images, identified more than a thousand million candidate objects. The vast majority of them turned out to be background stars and even-more-distant galaxies. A small fraction, however,were observed to move slowly across the sky over successive observations, the telltale sign of a TNO.


One such object was identified on 12 separate images. The astronomers informally dubbed it DeeDee, which is short forDistant Dwarf. The optical data from the Blanco telescope enabled the astronomers to measure DeeDee's distance and orbital properties, but they were unable to determine its size or other physical characteristics. It was possible that DeeDee was a relatively small member of the Solar System, yet reflective enough to be detected. Alternatively, it could be uncommonlylarge and dark, reflecting only a tiny portion of the feeble sunlight that reaches it; both scenarios would produce identical optical data. Since ALMA observes the cold, dark Universe, it is able to detect the heat -- in the form of millimetre-wavelength radiation -- emitted naturally by cold objects in space. The heat signature from a distant Solar-System object would be directly proportional to its size. By comparing the ALMA observations to the earlier optical data, the astronomers had the information necessary to calculate the object's size. Objects like DeeDee are cosmic leftovers from the formation of the Solar System. Their orbits and physical properties reveal important details about the formation of planets, including the Earth.This discovery shows that it is possible to detect very distant,slowly moving objects in the Solar System. The researchers note that the same technique might be used to detect the hypothesized'Planet Nine' that may reside far beyond DeeDee and Eris.

[YesNo]

Interesting that cold objects emit heat that can be detected by ALMA. I didn't know that was detectable. I can see how reflected light can lead one to mistakes about the size of the object because of the different reflective properties of the object.

[Danik 2016]

Its quite a minor point, but I am wondering at the criteria for chosing names for their discoveries. They used to be better when there were fewer clestial bodies found and they stuck to the names of Greek gods. Nowadays there is a quite anticlimatic lettering and numbering of the new finds going on.
DeeDee is cute.

[Dreamwoven]

Its quite a minor point, but I am wondering at the criteria for chosing names for their discoveries. They used to be better when there were fewer clestial bodies found and they stuck to the names of Greek gods. Nowadays there is a quite anticlimatic lettering and numbering of the new finds going on.
DeeDee is cute.

Yes the universe is unbelievably huge, and I see no way of going back to the old naming system of Greek gods.

[Danik 2016]

I found some links on the subject of naming celestial objects:
https://en.wikipedia.org/wiki/Astronomical_naming_conventions

"Celestial nomenclature has long been a controversial topic. At its inaugural meeting in 1922 in Rome, the IAU standardized the constellation names and abbreviations. More recently IAU Committees or Working Groups have certified the names of astronomical objects and features. In the following links you can find further information on how different objects and features are named."
https://www.iau.org/public/themes/naming/

[Dreamwoven]

That was enterprising of you Danik. It is clear that the whole business of nomenclature in astronomy is very problematic. We have ended up with an alpha-numeric soup that astronomers have created, for lack of an alternative terminology. Perhaps it is inevitable give how fast our knowledge of space as grown in recent years.

[Dreamwoven]

This item is interesting.

https://www.universetoday.com/135672/mars-project-von-brauns-ideas-mars-mission-collaboration-vintage-space/

[YesNo]

It is interesting that in the 1940's people thought there might be plants and animals on Mars.

[Dreamwoven]

I didn't know that!

[Danik 2016]

This item is interesting.

https://www.universetoday.com/135672/mars-project-von-brauns-ideas-mars-mission-collaboration-vintage-space/

Interesting article, DW. I think all the conquests start with the adventures of the imagination.

[Danik 2016]

It is interesting that in the 1940's people thought there might be plants and animals on Mars.

I didn´t know that either. Again it reminds me of the beginning of the Modern Age when people thought the oceans were full of monsters.

[Danik 2016]

Using math to investigate possibility of time travel

"After some serious number crunching, a researcher says that he has come up with a mathematical model for a viable time machine: a Traversable Acausal Retrograde Domain in Space-time (TARDIS). He describes it as a bubble of space-time geometry which carries its contents backward and forwards through space and time as it tours a large circular path. The bubble moves through space-time at speeds greater than the speed of light at times, allowing it to move backward in time."

https://www.sciencedaily.com/releases/2017/04/170427091717.htm

[Danik 2016]

http://www.online-literature.com/forums/showthread.php?58680-Say-next-word&p=1339424&viewfull=1#post1339424

[Dreamwoven]

Interesting, but the theory needs testing in practice.

[YesNo]

The article says that we need "exotic matter" to make the time machine work, but this has not been discovered. So this time machine is probably not a feasible test for our current gravitational theory.

Moffat ("Reinventing Gravity") hoped future instruments to test gravitational waves will provide evidence of what the universe was like closer to the big bang. That would test Einstein's gravitational theory as well his own modified gravitational theory.

[Danik 2016]

Interesting images of Jupiter regarding the study of its atmosphere shot by Juno mission. On the news today

http://edition.cnn.com/2017/05/25/us/nasa-jupiter-juno-mission-observations-first-results/

[Dreamwoven]

A couple of good articles:

https://www.universetoday.com/135719/new-ideas-mysterious-tabbys-star-gigantic-planet-planet-rings/

https://www.universetoday.com/135721/nasa-moves-mission-metal-asteroid-psyche/

[Magnocrat]

There is a considerable evidence to support the Big Bang hence is called a theory and not a hypothesis. Theories can be adjusted but are generally well supported like the theory of evolution. Hypotheses are attempts to explain the facts.
Karl Popper developed the concept of falsifiability and if a hypothesis cannot be falsified it can not be held to be scientific.

[Dreamwoven]

This isn't about the Big Bang, but about explaining the variability of the changing appearance of Tabby's Star:

"This explanation not only offers an entirely natural account of what could be causing the star to dim, but also offers a prediction that (if true) would confirm their theory."

Or are we not talking about the same thing?

[Magnocrat]

I didn't realise there were other threads on astronomy. I did a search and came up with nothing. There are well over 600 threads on serious discussions alone, yet I got no hits. Perhaps I am doing something wrong in my searches...

Anyway, space travel owes a lot to the work of someone I never heard of before - Michael Minovitch and the concept of gravity assist. See this website for details: http://gravityassist.com. Briefly until then rockets were shot up without using the slingshot technique of building up speed by this method, often several times, for example by circling the moon en route to develop enough slingshot speed to reach the goal.

Big Bang (https://en.wikipedia.org/wiki/Big_Bang) is still a theory. I can't even see how it can be proved, but one never knows…

Enormous strides in recent years, and have mapped all the inner planets and their moons with robot probes that do the job without risking human lives by sending people up into space.
A theory is well founded unlike a hypothesis which is an attempt to explain the facts.
The Big Bang is widely accepted and fits the bill just as the theory of evolution.
Karl Popper has put forward the falsification test for scientific hypothesis if it cannot be falsified it is not scientific. Freud's hypothesis of the ego superego and id is such an unfalsifiable type. Popper points out that because a hypothesis cannot be falsified does not mean it is not useful.

[Dreamwoven]

Yes, I think we are not at odds on this point at all.

[Dreamwoven]

I don't publish a post every day, only if there is interesting news that catches my attention.

[tailor STATELY]

Juno's dance with Jupiter... https://www.nasa.gov/press-release/a-whole-new-jupiter-first-science-results-from-nasa-s-juno-mission

[Dreamwoven]

Great images of Juno's close pass of Jupiter! Thanks tailor.

[Danik 2016]

I don't publish a post every day, only if there is interesting news that catches my attention.

I agree with you, but just now there are some about Tabby and Jupiter.

[Danik 2016]

Juno's dance with Jupiter... https://www.nasa.gov/press-release/a-whole-new-jupiter-first-science-results-from-nasa-s-juno-mission

I enjoyed this sequence of pics very much.

[Dreamwoven]

There is a post today on fusion as a future source of energy. Bit technical, perhaps, but China, US and Europe are all working on it: https://www.universetoday.com/135753/far-away-fusion-unlocking-power-sun/

[Dreamwoven]

2 links today: this one on the lunar orbiter: https://www.universetoday.com/135778/lunar-orbiter-takes-meteorite-strike-right-camera/

and this one on Juno, continuing to surprise us: https://www.universetoday.com/135765/juno-ready-tell-us-found-jupiter/

[Dreamwoven]

This is the clearest explanation I have found of the Big Bang Theory:

https://www.universetoday.com/135791/cosmic-inflation-quest-understand-earliest-universe/

[Dreamwoven]

This is what resides at the centre of the Milky Way Galaxy: a supermassive black hole. Read about it here:

https://www.universetoday.com/135799/exactly-see-star-splashes-black-hole-event-horizon/

[Danik 2016]

Just read the link on Jupiter- Stunning data. Never thought of Jupiter as a stormy planet.

[Dreamwoven]

I think most planets are stormy, and many moons are, too.

[Dreamwoven]

https://www.universetoday.com/135863/nasa-planning-test-pulsars-cosmic-navigation-beacons/

[Danik 2016]

Interesting article about Neutron planets, but the adds bar that doesn´t close is anoying.

[Danik 2016]

"Icy Water Worlds That Might Host Life

Alien life may be lurking right in Earth's cosmic backyard. Some of the icy moons of Saturn and Jupiter are known to harbor subsurface oceans that could provide habitable environments."

http://www.space.com/35469-solar-system-habitable-icy-worlds-infographic.html

[YesNo]

This is what resides at the centre of the Milky Way Galaxy: a supermassive black hole. Read about it here:

https://www.universetoday.com/135799/exactly-see-star-splashes-black-hole-event-horizon/

It is interesting that these scientists doubted the existence of the event horizon given current gravitational theory. I would have thought that black hole and event horizon were two sides of the same concept. However, that they did not find a solid object there the size of the event horizon doesn't mean there are black holes causing the behavior of visible stars at the center of galaxies. It could be that the gravitational theory is incorrect at that scale.

[Dreamwoven]

I think most planets are stormy, and many moons are, too.

You must have a different version of Space to the one I get. A lot more info on the moons of Saturn and other large planets. Very interesting, especially the possibility of a special probe to investigate.