Astronomy

[Dreamwoven]

I am still a member of the Society for Popular Astronomy and this is an extract from one of their email bulletins, much interesting stuff:

Society for Popular Astronomy [email protected]
11:14 (31 minutes ago) to me

The SOCIETY for POPULAR ASTRONOMY
Electronic News Bulletin No. 420 2016 April 17

Here is the latest round-up of news from the Society for Popular Astronomy. The SPA is arguably Britain's liveliest astronomical society, with members all over the world.

YOUNG, UNATTACHED 'JUPITER' FOUND IN SOLAR NEIGHBOURHOOD

Carnegie Institution for Science

A team of astronomers has discovered one of the youngest and brightest free-floating planet-like objects in reasonably close proximity to the Sun. At an age of only 10 million years, the object identified as 2MASS J1119-1137 is between four and eight times the mass of Jupiter, and hence falls in the mass range between a large planet and a small brown-dwarf star. From data obtained by WISE and other ground-based telescopes, 2MASS J1119-1137 was identified by its unusual colours: it emits much more light in the infrared part of the spectrum than would be expected if it had already aged and cooled. The challenge of identifying such rare objects is distinguishing them from a multitude of potential interlopers. Much more commonly, distant old and red stars residing in the far reaches of our Galaxy can display the same characteristics as nearby planet-like objects. When the light from the distant stars passes through the large expanses of dust in our Galaxy on its way to our telescopes, it gets reddened, so those stars can pose as potentially exciting nearby young planet-like objects when actually they are not that at all. With knowledge of such common misidentifications, the team immediately checked its findings using the FLAMINGOS-2 spectrograph instrument on the Gemini South telescope in Chile. It promptly confirmed that 2MASS J1119-1137 is in fact a young low-mass object in the solar neighborhood, and not a distant reddened star.

Next, the team wanted to determine the age of the object. Gemini observations showed only that the object was younger than about 200 million years. If it were much younger, it could actually be a free-floating planet -- an analogue of our own Jupiter, yet without a host star. The final piece of the puzzle was contributed by the FIRE spectrograph on Carnegie's 6.5-m telescope in Chile. FIRE measured the line-of-sight velocity of 2MASS J1119-1137. Combining that measurement with the sky motion of 2MASS J1119-1137, the team discovered that it belongs to the youngest group of stars in the solar neighbourhood. That group contains about two dozen 10 million-year-old stars, all moving together through space, and is collectively known as the TW Hydrae Association. Being 'nearby', 95 light-years away, 2MASS J1119-1137 only narrowly misses being the brightest free-floating planet analogue. That position is held by another object known as PSO J318.5−22, discovered three years ago. However, at an age of 23 million years, PSO J318.5−22 is more than twice the age of 2MASS J1119-1137, and is more massive. Discovering free-floating planet analogues like 2MASS J1119-1137 and PSO J318.5−22 offers an opportunity to study giant planets outside the Solar System, because free-floating planet candidates are much easier to scrutinize than planets orbiting around other stars. Objects like 2MASS J1119-1137 are drifting in space all alone and our observations are not overwhelmed by the brightness of an adjacent host star.

This is just one item in a list of news items.

[YesNo]

It is good to have something like this relatively nearby to study. Just how far away is 95 light years relative to other objects in the universe? How large is the solar neighborhood?

[Dreamwoven]

A light year takes one year at the speed of light to cover. Nothing apart from light travels that fast. This is one estimate from http://www.universetoday.com/75691/how-big-is-the-milky-way/, take 100,000 light years from one end to the other.

[YesNo]

Querying the internet, the Andromeda galaxy is 2.5 million light years away. As you mentioned, our galaxy is 100,000 light years across. Alpha Centauri is 4.4 light years away. So these objects at 95 light years away still seem quite far from us. I wonder how big the sun's local neighborhood is? I suppose that could be some arbitrary number say 100 or 200 light years.

I guess Alpha Centauri (about 4 light years away) is close enough to hope those postage stamp size probes would be able to make the journey in a reasonable time.

[Dreamwoven]

Yes, as you say, we still haven't properly explored our own sun's local neighbourhood. We are still not even sure what planets there are, and only done preliminary scans of some of the ones we do know. Mars is probably the best explored, but again only very preliminary.

[Dreamwoven]

Today, Space.com came up with this interesting post on planets going round stars:

http://www.space.com/32623-stars-wobble-could-reveal-earth-like-exoplanet.html

[YesNo]

It looks like Gliese 832c may not be "Earth 2.0" as previously thought.

[Dreamwoven]

I guess we will eventually know whether we have a new planet or two in orbit round the sun.

[Dreamwoven]

http://earthsky.org/space/watch-nasa-build-james-webb-space-telescope

This is the next generation of space telescopes currently being built.

This is about the moon recently discovered going round the dwarf planet MakeMake, spotted by Hubble: http://_source=EarthSky+News&utm_campaign=cb53183cd8-EarthSky_News&utm_medium=email&utm_term=0_c643945d79-cb53183cd8-394044013

[Dreamwoven]

http://earthsky.org/space/watch-nasa-build-james-webb-space-telescope

This is the next generation of space telescopes currently being built.

This is about the moon recently discovered going round the dwarf planet MakeMake, spotted by Hubble: http://_source=EarthSky+News&utm_campaign=cb53183cd8-EarthSky_News&utm_medium=email&utm_term=0_c643945d79-cb53183cd8-394044013

Its got a long url, I hope it works!

[YesNo]

I watched the video in the first link. I liked the phrase "universe's first light" used there. I was not able to access the second link.

[Dreamwoven]

The second link is not accessible for me either.

[Dreamwoven]

EarthSky is about how the Oort Cloud got its name: a Dutch astronomer in 1950: http://earthsky.org/space/jan-oort-biography-contributions-oort-cloud.

[YesNo]

It is interesting that the existence of the Oort cloud is still considered a theory, but those comets have to come from somewhere.

[Dreamwoven]

The problem is that the Oort Cloud is itself a concept rather than proven fact. It covers a huge area of space, See https://en.wikipedia.org/wiki/Oort_cloud

[Dreamwoven]

Extract from Society for Popular Astronomy:

Oddly enough Gaia is not described in Wikipedia. Definitely a miss as Gaia was launched in 2013:

Saturday’s London meeting: Gaia – the Milky Way and Beyond
It sounds like something from Star Trek: ‘Its five-year mission – to seek out new worlds, to reveal cataclysms deep in the Universe, and to discover strange objects that as yet we can’t even understand.’ But this is not the Starship Enterprise, it is the European Space Agency's flagship Gaia mission, launched in 2013. It will produce the most accurate three-dimensional map of our own galaxy, the Milky Way. As well as surveying millions of stars throughout the Galaxy, Gaia will reveal transient events taking place far out in the rest of the Universe, including stars exploding as supernovae and being swallowed by black holes.
Our main speaker, Dr Morgan Fraser of Cambridge University, will explain how Gaia will achieve its amazing precision measurements, and give us a taste of some of the science highlights so far.
Following the break, Robin Scagell will look at some of the highlights in the sky for the next three months, including the Transit of Mercury. Comet Section Director Stuart Atkinson will speak about Comets: Fear, Fact and Fiction and discuss why comets have been blamed for so many disasters in history, plus taking a look at the Rosetta mission.
The meeting is open to all SPA members and friends, and begins at 2 pm this coming Saturday, 30 April. The venue is the Khalili Lecture Theatre of the School of Oriental and African Studies, near Russell Square, London WC1H 0XG. The nearest tube station is Russell Square. For a map of the location and more details, go to the SPA website.

[YesNo]

Our main speaker, Dr Morgan Fraser of Cambridge University, will explain how Gaia will achieve its amazing precision measurements, and give us a taste of some of the science highlights so far.

In all of these studies I wonder what the precision is of the measurements including a measure of the margin of error. On top of that is how those results are obtained.

[Dreamwoven]

I think this has to be two questions that should hopefully be answered at the session. Information on Gaia seems to be very sparse.

[Dreamwoven]

Repeating bursts of radio waves from mysterious object (from an article in Popular Astronomy): "Fast Radio Bursts" (FRB) from outside the Milky Way have been noted since they were first discovered in 2001. See https://en.wikipedia.org/wiki/Fast_radio_burst. They remain an unexplained mystery.

[YesNo]

That was the first I heard of fast ratio bursts. But there is a lot I haven't heard of. It appears they are still rare. It looks like they come in a repetitive fashion which is probably what makes them stand out.

[Dreamwoven]

The good news is that measures are being taken to sharpen their observation tools to enable finer pinpointing of the source of FRBs. "The event must be extremely energetic to be detectable from earth" (p.6).

[Dreamwoven]

In the same issue there is an article on ice giants (Neptune and Uranus). We know very little about them, all from Voyager 2 over 30 years ago. They are definitely different from Jupiter and Saturn which are not ice giants but which have gaseous envelopes. So many questions need to be addressed.

[YesNo]

It is interesting that Neptune and Uranus are ice giants and unlike Jupiter and Saturn. I previously assumed those four planets were similar being so large.

I remember looking at Mars and Saturn in the early morning last week as the Moon passed above them.

[Dreamwoven]

I also assumed the four giant planets were similar, but they are not. The further out ice giants are also different from each other, as well as from the two gaseous giants, Jupiter and Saturn. Neptune's surface is tossed by violent tornados and supersonic winds and has an earth-sized "Great Dark Spot". Uranus is deep-frozen.

There is a lot more about the ice giants, especially their many moons. Neptune has 14 moons, one, Triton, being bigger than Pluto and accounting for 99 percent of the mass of matter encircling Neptune. It orbits Neptune in the opposite direction to the planet's rotation, suggesting it was captured by Neptune, so is probably a dwarf planet from the Kuiper Belt.

There is a lot more about the moons of the ice giants, planets which, until the 1980s were just specks in space. They need re-visiting to understand them better.

Uranus has 27 moons (!), two of which Cordelia and Ophelia are described as shepherd moons for the epsilon ring around Uranus.

Source: Popular Astronomy May/June 2016 "Return to the Ice Giants" by Joseph Scaife (pp. 15-17).

[YesNo]

That Triton might have been captured by Neptune is a nice way to think about it. I didn't know it had an orbit opposite to the planet's rotation. If Neptune has tornadoes it must have an atmosphere.

[Dreamwoven]

I think "tornado-like" would be more accurate. Neptune doesn't have an atmosphere as we think of it on earth.

[Dreamwoven]

Most planets have an atmosphere, commonly dominated by ammonia or methane. No other planet discovered so far has oxygen and hydrogen (H20) other than earth.

[YesNo]

Why are ammonia or methane so common?

[Dreamwoven]

I have no idea.

[Dreamwoven]

I suspect it is because we have studied so few worlds in enough detail. We know about 9 worlds in our solar system. Perhaps in time we will have more world's to study and be able to see patterns better.

[YesNo]

Perhaps the existence of life on Earth helps change the atmosphere.

[Dreamwoven]

Or indeed, vice versa...

[tailor STATELY]

Re: Atmospheres - Temperature and pressure appear to be the main determinate on how hydrogen (being the most abundant element along with helium in the universe) and other elements combine/sublime/condense on colder planets.

Sol System Planet atmospheres: http://www.universetoday.com/35796/atmosphere-of-the-planets/

http://lasp.colorado.edu/education/outerplanets/giantplanets_whatandwhere.php


ATMOSPHERES... The atmospheres of Jupiter and Saturn are made almost entirely of hydrogen and helium, although there is some evidence they contain hydrogen compounds. Uranus and Neptune are made primarily of hydrogen compounds, with smaller traces of hydrogen, helium, metal and rock. The most common hydrogen compounds are methane (CH4), ammonia (NH3), and water (H2O).
The farther away a planet is from the Sun, the cooler its atmosphere will be. This means that the same gases will condense to form clouds at different altitudes on different planets because the condensation of a gas requires a specific amount of pressure and temperature. Ammonia, ammonium hydrosulfide and water make up the 3 cloud layers of Jupiter and Saturn. You can see from the graph to the right that these condense at lower altitudes in Saturn's atmosphere than they do in Jupiter's atmosphere.

Ta ! (short for tarradiddle),
tailor STATELY

[Dreamwoven]

The Universe Today articles in your link, tailor, are interesting but don't tell us more than the Popular Astronomy article in an earlier post in this thread.

Its been 30 years since the Voyager 2 flyby, so these planets need to be revisited. The 2 ice giants Uranus and Neptune remain the planets we know little about. They are very different. Neptune radiates more heat out into space than it receives from the sun, while Uranus is more sealed in under its icy mantle. The many moons of these two ice giants also remain largely unexplored.

The Voyager 2 Flyby was not enough to even identify and describe many of these moons. Uranus has 27 "known" moons, while Neptune has 14, one of which, Triton, is probably a captured dwarf planet, accounting for 99% of all the mass in orbit around Neptune. See post #524.

[Dreamwoven]

Three alien planets around a tiny cold star might be a good place to search for life (http://www.space.com/32761-three-alien-planets-trappist-1-star-could-support-life.html). Doesn't mean intelligent life or even advanced forms of non-intelligent life.

Also, it seems we are still getting info from Cassini (http://www.nasa.gov/mission_pages/cassini/main/index.html) on Saturn's moon Titan (http://earthsky.org/space/a-pure-methane-sea-on-titan). This despite the claims in Popular Astronomy that we are not getting any new material to add to what we knew from the Voyager 2 probe 30 years ago.

[Dreamwoven]

I've got my Mac back and can now create links again! Windows 10 was useless, while I used it the links disappeared!

[YesNo]

For some reason those exoplanets around tiny stars are easier to study given our current technology. At least that is what I got from the article, but I would have thought larger systems would be easier to spot. Perhaps these smaller ones must be compact for the exoplanets to be in their sun's habitable zone and that compactness is easier for us to spot.

[Dreamwoven]

I will expect a retraction in the next issue of Popular Astronomy of the claim that we get no new material since Voyager 2. Cassini is still sending back data from Saturn's moon, Titan, and the lakes of pure methane on that moon.

[YesNo]

Knowing that the lakes are pure methane does seem to be new information. The missions to Ceres and Pluto offered plenty of new information. I still wonder what those bright spots are on Ceres.

[Dreamwoven]

The bright spots on Ceres is a quite separate issue. The close-up views of Ceres suggest they may be salt deposits. This 2016 discussion of the Ceres project (to be extended to 2017) is the latest I have found: https://spaceflightnow.com/2016/04/06/dawn-mission-expected-to-go-into-overtime-at-ceres/

[YesNo]

They mentioned that it is hard to keep things bright on a planetary surface, but this one has no atmosphere to deposit dust on the surface.

[Dreamwoven]

I guess we will see how the work being done on Ceres will be improved by the one year extension of the visit.

[Dreamwoven]

Planet 9 (http://earthsky.org/space/why-planet-9-shouldnt-exist) (or Planet 10 if we include Pluto) has a very wide and distant orbit round the sun. The theory is that it was captured and is in a bizarre highly elongated orbit. See also this post (http://earthsky.org/space/why-planet-nine-might-be-for-real) from EarthSky.

If it is verified - and that could take a long time, with such an orbit, many centuries perhaps, it would be sensational.

Read the two EarthSky posts for more information.

[YesNo]

It is an interesting idea that the elliptical orbit of planet 9 might have been caused by a star early in the formation of the solar system rather than something wandering about that the Sun picked up.

[Dreamwoven]

Kepler is finding many Milky Way planets (http://www.space.com/32850-nasa-kepler-telescope-finds-1284-alien-planets.html) that could harbour life. That is a long way from finding planets that do harbour life, but it is quite a radical change.

We took the train to Bollnäs yesterday and I borrowed a copy of Populär Astronomi. I may make a post on some of the material in it.

[YesNo]

It looks like tens of billions of potentially habitable planets in the Milky Way.

[Dreamwoven]

In Populär Astronomi June 2014 (2 years ago) there was an item on a dwarf planet that I had never before heard of. It's called Sedna (https://en.wikipedia.org/wiki/90377_Sedna), with a diameter of only 450 km, just a fifth of Pluto's. This is an Oort Cloud denizen, not a Kuiper Belt denizen like Pluto. It takes 11,400 years for Sedna to complete one orbit round the sun.

There are in fact many such Trans-Neptunian objects (https://en.wikipedia.org/wiki/List_of_trans-Neptunian_objects), some 270 (!) counted so far. Some are not even dwarf planets, as they could easily have their course changed by a large outer planet. They are also known as Centaurs (https://en.wikipedia.org/wiki/Centaur_(minor_planet)).

So there we are, I have been ignorant of this and now start to catch up...

[Dreamwoven]

Space.com has an article on a dwarf planet informally dubbed Snow White (http://www.space.com/32863-dwarf-planet-snow-white-size-revision.html). It is larger than hitherto estimates as its surface is darker than expected. This makes it the third largest dwarf planet in our solar system after Pluto and Eris, though this is just a guess. It completes an orbit of the sun every 547.5 years, while Pluto's orbit is 248 years.

These outer bodies of the solar system make them less likely to receive a visit in the near future, especially as their orbits are in many cases highly elliptical. For now we will have to await newer and more powerful telescopes to learn more about them. The same is likely to be true of the 9th planet (see an earlier post on this).

[YesNo]

It seems that Snow White should have been nicknamed Rose Red. The oblong shape of Haumea is also unusual.

[Dreamwoven]

This is from my subscription to Popular Astronomy in the periodic newsletters they send out. It is the strange sausage shaped object that YesNo mentioned in his latest post in this thread.

FRAGMENT PROBABLY FROM THE EARTH'S FORMATION RETURNS

ESO

Astronomers have found a unique object that appears to be made of inner-Solar-System material from the time of the Earth's formation, which has been preserved in the Oort Cloud far from the Sun for thousands of millions of years. Observations with the Very Large Telescope, and the Canada-France-Hawaii Telescope, show that C/2014 S3 (PANSTARRS) is the first object to be discovered on a long-period cometary orbit that has the characteristics of a pristine inner-Solar-System asteroid. It may provide important clues as to how the Solar System formed. Observations indicate that it is an ancient rocky body, rather than a contemporary asteroid that strayed out. As such, it is one of the potential building blocks of the rocky planets, such as the Earth, that was expelled from the inner Solar System and preserved in the deep freeze of the Oort Cloud for thousands of millions of years. C/2014 S3 (PANSTARRS) was originally identified by the Pan-STARRS1 telescope as a weakly active comet a little over twice as far from the Sun as the Earth. Its current long orbital period (around 860 years) suggests that its source was in the Oort Cloud, and it was nudged comparatively recently into an orbit that brings it closer to the Sun. The team immediately noticed that C/2014 S3 was unusual, as it does not have the characteristic tail that most long-period comets have when they approach so close to the Sun. As a result, it has been dubbed a Manx comet, after the tailless cat. Within weeks of its discovery, the team obtained spectra of the very faint object with the Very Large Telescope in Chile.

Study of the light reflected by C/2014 S3 indicates that it is typical of asteroids known as S-type, which are usually found in the inner asteroid main belt. It does not look like typical comets, which are believed to form in the outer Solar System and are icy rather than rocky. It appears that the material has undergone very little processing, indicating that it has been deep-frozen for a very long time. The very weak comet-like activity associated with C/2014 S3, which is consistent with the sublimation of water ice, is about a million times lower than is exhibited by active long-period comets at similar distances from the Sun. Astronomers conclude that the object is probably made of fresh inner-Solar-System material that has been stored in the Oort Cloud and is now making its way back into the inner Solar System. Various theoretical models are able to reproduce much of the structure that we see in the Solar System. An important difference between the models is what they predict about the objects that make up the Oort Cloud. Different models predict significantly different ratios of icy to rocky objects. This first discovery of a rocky object from the Oort Cloud therefore initiates a potentially important test of the different predictions of the models. The authors estimate that observations of 50--100 such Manx comets will be needed to distinguish between the current models, so it promises to be a long time before such a study can throw much light on the origins of the Solar System.

[YesNo]

I wonder how those Manx comets got out that far. Perhaps the inner planets kept pushing them away rather than attracting them.

[Dreamwoven]

I had to look up Manx Comet to find out more about them, tail-less comets like the manx cat. But I still can't understand how "the inner planets keep pushing them away rather than attracting them." What do you mean by that?

[YesNo]

I used to think that objects where drawn into a planet by the planet's gravity and then I recall reading that objects can also be pushed away by gravity as well. This would help push objects originating close to the Sun further out.

[Dreamwoven]

I've never heard of that myself. I don't suppose you can cite a reference...

[YesNo]

I don't have a reference. I learnt it from this thread. It would be how probes use the gravity of other planets to extend their range. I'll see if I can find some reference later today.

[YesNo]

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.

Here's a reference you provided for gravity assist that is what I was referring to when using a planet's gravity to move a probe further. I assume this is similar to the way a planet would clear its path by pushing objects out of the way rather than absorbing those objects.

[Dreamwoven]

It is most unlikely that any Oort Cloud objects will come anywhere near the solar system. A Kuiper Belt object like Pluto is vastly nearer but one probe, New Horizons did make it, taking advantage of a one-in-250 years conjunction that brought Pluto nearer. We may just be lucky - or at least later generations - 11+ thousand years for one orbit is a long time to wait...


In Populär Astronomi June 2014 (2 years ago) there was an item on a dwarf planet that I had never before heard of. It's called Sedna (https://en.wikipedia.org/wiki/90377_Sedna), with a diameter of only 450 km, just a fifth of Pluto's. This is an Oort Cloud denizen, not a Kuiper Belt denizen like Pluto. It takes 11,400 years for Sedna to complete one orbit round the sun.

There are in fact many such Trans-Neptunian objects (https://en.wikipedia.org/wiki/List_of_trans-Neptunian_objects), some 270 (!) counted so far. Some are not even dwarf planets, as they could easily have their course changed by a large outer planet. They are also known as Centaurs (https://en.wikipedia.org/wiki/Centaur_(minor_planet)).

So there we are, I have been ignorant of this and now start to catch up...

[Dreamwoven]

Yesterday we saw the first half of a Swedish TV Program on Origami (https://en.wikipedia.org/wiki/Origami) as applied to nature, how leaves and flowers open up to their full size from buds. They fold out to their full size. The Swedish language uses the origami principle to describe development. The word utvekla means to develop but also means to bend out.

Apart from being interesting in itself I remembered that there are plans in development to use solar wind for space travel (https://en.wikipedia.org/wiki/Solar_sail). The applications (https://en.wikipedia.org/wiki/Solar_sail#Applications) of this are many and potentially far-reaching. There is a lot of material on this in all it variations in the above Wikipedia article on Solar Sail applied to un-manned space travel. Speed builds up slowly but faster and faster. Travel to the outer planets (e.g. Neptune 8.5 years) and even to the Oort Cloud are possible: "Such a sail would take "Two and a half years to reach the heliopause, six and a half years to get to the Sun’s inner gravitational focus, with arrival at the inner Oort Cloud in no more than thirty years."

[YesNo]

Thirty years seems a reasonable time to wait. You mentioned earlier about using lasers to send very small probes even faster and further should those ideas get developed.

[Dreamwoven]

I suspect some of the nearer places would be high priority, like the moons of the outer planets, Uranus and Neptune, for example. It would be handy to complete the mapping of many moons of the outer planets, and after that the nearer reaches of the Oort Cloud.

[YesNo]

Or landing on Ceres to find out what those bright spots are. We would need something to do while those other probes were en route.

[Dreamwoven]

http://earthsky.org/brightest-stars/alpha-centauri-is-the-nearest-bright-star: it is "only" 4.22 light years away. And we still don't know how many stars (suns) are in it. Probably 3.

[YesNo]

It looks like I am too far north the see Alpha Centauri although they say it is the third brightest star in the sky.

[Dreamwoven]

The problem with Alpha Centauri is that one of the stars is so bright and the others are so dim (being brown dwarf starts near the end of their lives ) that the bright star makes it hard to see the others. We think there are 3 in all, but not sure.

[YesNo]

It would be kind of strange having three suns in the sky on any planet surrounding one of the stars comprising Alpha Centauri. I hope there is some nighttime.

[Dreamwoven]

In Populär Astronomi over a year ago something I never knew came out. On 9 May last year Dawn began its spiral descent to its lowest position, some 375 km above Ceres. It will be continuing to collect data for as long as possible, but it will eventually become a permanent satellite of Ceres, its own (artificial) moon.

[YesNo]

I thought Dawn would crash into Ceres. I guess it is better to have it orbit as long as possible.

[Dreamwoven]

It has been nearly a year ago that New Horizons left Pluto and headed deeper into the Kuiper Belt. It has found an icy body 150 km wide and rotating quite rapidly, every 5.4 hours, fast for a Kuiper Belt Object (KBO). See http://www.space.com/32946-new-horizons-probes-object-beyond-pluto.html.

[Dreamwoven]

http://www.space.com/32973-supermassive-black-holes-born-big.html. This post on black holes shows how fast knowledge and theory grow...

[YesNo]

The article mentioned they only have candidates for what might be black holes. However, the conjecture that massive black holes did not grow to their massive size but started off big is interesting.

[Dreamwoven]

This short video shows how varied the terrain is on Pluto: http://earthsky.org/space/best-close-up-of-plutos-surface.

[YesNo]

The nitrogen ice plains where the strangest feature. I didn't expect anything like that being there.

[Dreamwoven]

Galaxy Zoo is a way of classifying galaxies (https://www.galaxyzoo.org/). I read an article in Popular Astronomy on citizen science by Alice Sheppard (p.9). School pupils found the subject confusing as they "never really knew the answers". "This is a fundamental misconception of science that is developed in schools" as a monolith, a mystery and an authority, rather than a method." "They didn't want to get it wrong"(Ben Goldacre (https://en.wikipedia.org/wiki/Ben_Goldacre)) "Only by muddling around, getting confused, can we improve our knowledge. But for school children who had only been taught to pass tests, this was daunting."

There is more, but the above is a good way to describe it succinctly.

[Dreamwoven]

This post had me rolling in the aisles. Very funny and very perceptive: http://www.space.com/33005-where-is-the-universes-edge-op-ed.html

[Dreamwoven]

The seas of Titan are methane, but the plan is to send a submarine to explore them for signs of primitive life. The idea is only at the planning stage and may take 20 years to implement:
https://www.nasa.gov/content/titan-submarine-exploring-the-depths-of-kraken/

[Dreamwoven]

http://earthsky.org/space/pluto-heart-sputnik-planum-geologically-active-young

Scientists with NASA’s New Horizons mission used state-of-the-art computer simulations to show that the surface of Pluto’s heart-shaped Sputnik Planum region is covered with churning ice “cells.” These icy cells are geologically young, less than a million years old.

[YesNo]

It was interesting that those nitrogen cells are active on Pluto. The planet isn't dead.

[Dreamwoven]

That's right, Pluto is very much an active dwarf planet.

[Dreamwoven]

The hunt for gravitational waves is on. See http://www.space.com/33094-lisa-pathfinder-gravitational-wave-tech-demonstration-results.html, an interesting post.

[YesNo]

The first video in that link was interesting. The gravitational ways occur when objects collide.

[Dreamwoven]

This selection of pics is of iridescent clouds. Rather pretty: http://earthsky.org/earth/i-saw-a-cloud-with-rainbow-colors-what-causes-it

[YesNo]

I don't recall if I've ever seen cloud iridescence before. There is an iridescence in some stones. I picked up one for my wife recently The stone is called Labradorite: https://en.wikipedia.org/wiki/Labradorite

[Dreamwoven]

I saw a lens cloud today, my first ever. Lenticular clouds they are called: see https://en.wikipedia.org/wiki/Lenticular_cloud

[YesNo]

Those lenticular clouds do look like big flying saucers. I guess I'd have to wait for them to beam me up to be sure.

[Dreamwoven]

Kepler has found a large planet orbiting 2 stars.

http://www.space.com/33155-biggest-tatooine-exoplanet-twin-suns-found.html

[YesNo]

What I found interesting about this new large gas exoplanet was that it was in the habitable zone and so its moons could have life. Imagine being in a solar system with two suns and then circling a gas giant like Jupiter.

[Dreamwoven]

http://earthsky.org/space/astronomers-to-observe-mystery-star. This is the star that was thought to have a Dyson Sphere built or being built around it. It will be under a year's constant observation to check it out.

[YesNo]

It would be nice to know if there is an alien megastructure around that star or not.

[Dreamwoven]

The point being made is that even if there is not, there must be another explanation.

[Dreamwoven]

Another billion dollar shot for NASA, I didn't even know of it until now. It is planned to orbit Jupiter and study its atmosphere, magnetic field, and more besides. The Juno Probe is still not in orbit around Jupiter, if the manoeuvre fails the probe will be shot out into space and be lost.

[tailor STATELY]

Saw that. I hope Jupiter's radiation doesn't work havoc with the instruments, though it will be inserted into a 2,672 mile orbit which should be safe. https://www.google.com/search?client=opera&q=Juno+Probe+jupiter&sourceid=opera&ie=UTF-8&oe=UTF-8

Ta ! (short for tarradiddle),
tailor STATELY

[Dreamwoven]

The item in the website Space was a bit unclear about the details, so fingers crossed on that one, Tailor!

[YesNo]

The name of the spacecraft, Juno, seems appropriate for the mission: https://en.wikipedia.org/wiki/Juno_(spacecraft)

[Dreamwoven]

More on the Juno probe, can be read at this website: http://www.space.com/33190-juno-spacecraft-jupiter-home-stretch.html

[Dreamwoven]

http://earthsky.org/space/youngest-fully-formed-exoplanet-k2-33b. This was an interesting read!

[YesNo]

Based on that article the number of known exoplanets is now 3,437.

[Dreamwoven]

http://earthsky.org/space/liquid-water-ocean-under-pluto-ice?

[YesNo]

If Pluto is potentially habitable that would expand the habitable zone where life is possible. I thought ice expanded when it froze which makes me wonder if Pluto hasn't already completely frozen.

[Dreamwoven]

http://www.space.com/33276-opal-pieces-found-in-antarctica-meteorite.html. This is a clue to the existence of life on earth.

The other thing to watch for is the Juno Mission, hoping the orbit insertion, due soon, works smoothly.

[YesNo]

If Earth's water comes from meteorites where did the meteorites get it?

[Dreamwoven]

That's a very good question. It highlights a weakness in our current understanding. i guess the answer is that water came to Planet Earth millions of years ago, when space was much more turbulent than today (is this even true?).

[Dreamwoven]

This post on Ceres and its white spots is of interest:
http://www.space.com/33302-ceres-bright-spots-new-composition.html

[Dreamwoven]

This post on the Juno Mission gives lots of new information: http://www.space.com/33298-nasa-juno-jupiter-mission-facts.html

[Dreamwoven]

This post one Pluto - http://earthsky.org/space/pluto-spacecraft-gets-new-mission-mu69 - has some interesting facts around the 2-year extension to its mission, as well as the picture of Pluto's surface.

[YesNo]

It is interesting that the computer aboard Juno can't hold as much memory as my laptop, not that I really use my laptop memory as much as I used to with the cloud being available. (Probably I should consider backing up what I have on the cloud somewhere else?)

That they might have got the explanation for the bright spots on Ceres wrong is to be expected. Sometimes we take speculations as if they are facts. It is good to be surprised by new speculations and evidence.

[Dreamwoven]

A new dark spot on Neptune: http://earthsky.org/space/a-new-dark-spot-on-neptune

[YesNo]

It is amazing how much of the knowledge of our solar system is recent. We should send more probes out.

[Dreamwoven]

There are several already, Mars exploration, New Horizons, and still getting material from the probe Dawn, to Ceres, and much work with telescopes, both from Earth and space-based telescopes. Here is also a discussion of growing food on Mars, on a permanent base (one-way only, for people to spend their lives on Mars) as a private initiative: http://earthsky.org/space/can-we-grow-food-on-mars

[YesNo]

We might as well give all of these a try. I would think we should first experiment with the Moon.

[Dreamwoven]

There are more that I missed. Cassini at Titan has been at work for nearly 20 years, just on Saturn and its moon Titan. It is quite hard to keep up with NASA but in addition there are new countries, like India.

[Dreamwoven]

This is the link to the Titan research: http://www.space.com/15257-titan-saturn-largest-moon-facts-discovery-sdcmp.html

[Dreamwoven]

This is a link to a discussion about "how can the universe expand faster than the speed of light?": http://www.space.com/33306-how-does-the-universe-expand-faster-than-light.html. Certainly hard to wrap anyone's mind around...

[Dreamwoven]

The Juno probe has successfully entered Jupiter's orbit. Read about it here: http://www.space.com/33343-nasa-juno-spacecraft-arrives-jupiter.html

[YesNo]

The article said that Juno made a flyby of earth to increase speed to get to Jupiter. So it must have come back to earth, but earth would have been at a different position in the solar system by then.

[tailor STATELY]

The article said that Juno made a flyby of earth to increase speed to get to Jupiter. So it must have come back to earth, but earth would have been at a different position in the solar system by then.... yup, it was quite a dance; the math must have been very dicey.

Ta ! (short for tarradiddle),
tailor STATELY

[Danik 2016]

Just read about it: New planet with 3 suns. The movements are very curious:
http://phys.org/news/2016-07-newly-planet-suns.html

[Dreamwoven]

That is, indeed a strange system of suns and planet, Danik!

[Dreamwoven]

They must have pulled it off, I wondered why NASA was so worried about the outcome.


... yup, it was quite a dance; the math must have been very dicey.

Ta ! (short for tarradiddle),
tailor STATELY

[YesNo]

I didn't know there were solar systems with three suns before. I wonder if there are solar systems with a larger number of suns.

[Dreamwoven]

It is possible. I've not been able to work out how much light any of the suns shed on the planet. I think the planet takes half a millenium to complete an orbit. Some of the suns may be so far away from the planet that they look like stars.

[Danik 2016]

I guess we are witnessing a new kopernican revolution. Our solar system that for a very long time was the only one, has become one of many. I wonder what new astronomical discoveries are in store.

[Dreamwoven]

Yes, it is s very exciting time in astronomy. There are even blogs in astronomy - "Eagle's Eye in the Sky" is one.

[Dreamwoven]

EXTREME TRANS-NEPTUNIAN OBJECTS AND PLANET 9
Plataforma SINC

In an effort to discover a ninth planet in the Solar System (Pluto no
longer having that distinction, being demoted), scientists in various
countries have been trying to calculate its orbit from the paths
followed by small bodies that move well beyond Neptune. Now,
astronomers from Spain and Cambridge University have confirmed, with
new calculations, that the orbits of the six extreme trans-Neptunian objects
that served as a reference to announce the existence of Planet Nine are
not as stable as it was thought. At the beginning of this year, astronomers
announced that they had found evidence of the existence of a giant planet
with a mass ten times larger than the Earth's in the confines of the Solar
System. Moving in an unusually elongated orbit, the planet would take
between 10,000 and 20,000 years to complete one revolution around the
Sun. To arrive at that conclusion, the team ran computer simulations with
input data based on the orbits of six extreme trans-Neptunian objects
(ETNOs): Sedna, 2012 VP113, 2004 VN112, 2007TG422, 2013 RF98
and 2010 GB174. Now, however, the team has considered the question
the other way round: how would the orbits of those six ETNOs evolve if a
Planet Nine, such as the one proposed, really did exist? With the orbit
indicated by the Caltech astronomers for Planet Nine, calculations show
that the six ETNOs would move in lengthy, unstable orbits. Those objects
would escape from the Solar System in less than 1.5 billion years, and in
the case of 2004 VN112, 2007 TG422 and 2013 RF98 they could
abandon it in less than 300 million years; what is more important, their
orbits would become unstable in just 10 million years, a really short time in
astronomical terms.

According to the new study, based on numerical (N-body) simulations, the
orbit of the new planet would have to be modified slightly so that the
orbits of the six ETNOs analysed would be really stable for a long time.
Those results also lead to a new question: are the ETNOs a transient and
unstable population or, on the contrary, are they permanent and stable?
The behaviour of those objects in one way or the other affects the
evolution of their orbits and also the numerical modelling. If the ETNOs
are transient, they are being continuously ejected and must have a
stable source located beyond 1,000 astronomical units (in the Oort
cloud) where they come from. But if they are stable in the long term,
then there could be many in similar orbits although we have not observed
them yet. In any case, the statistical and numerical evidence obtained
by the authors, both through this investigation and previous work, leads
them to suggest that the most stable picture is one in which there is
not just one planet, but rather several more beyond Pluto, in mutual
resonance. The situation is reminiscent of the one leading to the
discovery of Neptune, in which the French mathematician Urbain Le
Verrier was the first to "discover" a new planet by means of laborious
hand calculations based on the positions of Uranus, whereupon the German
astronomer J. G Galle directly observed it. If Neptune was the first
planet discovered by pen and paper, Planet Nine could be the first to
be discovered entirely from computerized numerical calculations.

[YesNo]

It is interesting that the orbits of the six trans-Neptunian objects are more erratic than expected.

[Dreamwoven]

Another Dwarf Planet has been discovered in the kuiper belt far beyond Pluto: http://www.space.com/33387-dwarf-planet-discovery-2015-rr245.html

[YesNo]

It looks like the odds favor many dwarf planets rather than one big planet 9.

[Danik 2016]

Here is a possible candidate. I'm impressed at the quantity of new discoveries.
http://www.space.com/33387-dwarf-planet-discovery-2015-rr245.html

[Dreamwoven]

It looks like the odds favor many dwarf planets rather than one big planet 9.
I don't think the large planet 9 idea is considered by anyone to be dismissed. See this link: http://www.news.com.au/technology/science/space/did-our-sun-steal-planet-9-from-another-star/news-story/

[Dreamwoven]

Yes, Danik, the smaller Pluto was found when New Horizons were looking to find another kuiper belt object worth investigating. It may even have its own moons, too, like Pluto does.

[Danik 2016]

I couldn´t open your link, DW, maybe because of international restrictions. I wonder what kind of impact all these findings will have on other sciences that have the untilnow known solar system for reference.

[desiresjab]

The Three Body Problem has been an unsolved nightmare for three centuries. The calculations are horrendous. Some might say it is finally solved, but the solution itself is horrendous and not some beautiful thing you can behold in a neat formula.

Isn't the fictional system in Game of Thrones a multi-sun system? I believe that is why they have their long winters, and why the occurrence of these winters is unpredictable and a matter of great concern to the citizens of that world. I notice a lot of darkness in the productions, which could be unrealistic, depending on the locations and masses of the suns.

[Dreamwoven]

I'm afraid I don't know the story of the Game of Thrones desiresjab, but it sounds interesting...

[YesNo]

The game of thrones is a TV show. I have only seen one episode of it with my daughter and since I don't watch TV, I probably won't see any more. There is a lot of violence with beautiful people in medieval settings behaving nobly and ignobly and dragons breathing fire. I can see how someone could get attracted to it even it if had only one sun. I don't know the underlying story either.

[Dreamwoven]

Juno is now in orbit round Jupiter. It is still a long way from Jupiter itself, but has to be careful not to be dragged into the planet itself, its field of gravitation being so great. So it is in an elliptic orbit, swinging closer to get information, the pulling away using Jupiter's powerful gravity to slingshot out again.

It all must be very delicate, to get it just right. No wonder the staff at NASA was a bit nervous...

See http://www.space.com/33406-juno-jupiter-orbit-first-photo.html

[August Guelfen]

Hello again,

If someone is interested in the indo german/nurse roots of "Game of Thrones", so he or she should read the "Thule", especialy the Edda Saga, that is the whole truth about the Song of Fire and Ice. Tolkien's Lord of the Rings is concepted the same way, but a bit more interesting, I guess... I read the "Thule" entirely, also the Edda Saga of indo german "apocalypse". But I am very lucky to be able to read old german, nowadays, I don't even know one person under 30 besides of me, who is able to read it, without being paid for it as historians or as scientists. Besides, their exist another funny thing,
called "The Guelphen Saga". It was written down the first time nearly 700 years ago, I guess... My old manhunter family is the best, beleave me... We hate and murder each other even sometimes today... We are indeed ol' dirty bastards of murder and mayhem... Can you imagine us at Christmas diner ?! It's great and more cold than in Sebiria in terms of emotions.

[YesNo]

The Thule sounds interesting. I haven't read any of them even in English. The Game of Thrones did remind me of Tolkien.

[Dreamwoven]

I'm puzzled what this has to do with astronomy?

[YesNo]

Probably nothing. I guess there was a wonder if the Game of Thrones was a fictional world with more than one sun.

[Dreamwoven]

I was referring to August Guelfen's post. I'm at a loss to know what it has to do with astronomy.

[Danik 2016]

Just to finish this off topic. I never watched Game of Thrones but I loved this description"There is a lot of violence with beautiful people in medieval settings behaving nobly and ignobly and dragons breathing fire.":D
I still hope to read a complete narrative and not just a comment by you, Yes/No.

[Dreamwoven]

This is a what-if? piece on sending a drone to Saturn's moon Titan a proposal by two private companies:
http://www.space.com/33412-nasa-aerobot-drone-saturn-moon-titan.html

[YesNo]

It is interesting that they would consider using the atmosphere on Titan to survey the planet rather than orbiting above the atmosphere.

[Dreamwoven]

HOW MARS' MOONS FORMED
CNRS

The origin of the two Martian moons, Phobos and Deimos, has been
uncertain. Owing to their small sizes and irregular shapes, they
strongly resemble asteroids, but no one has understood how Mars could
have captured them and made them into satellites with almost circular
and equatorial orbits. According to one theory, towards the end of
its formation Mars suffered a collision with a proto-planet; but then
why did the debris from such an impact create two small satellites
instead of one relatively enormous one, like the Earth's? Another
possibility is that Phobos and Deimos formed at the same time as Mars,
which would entail their having the same composition as their planet,
although their low density seems to contradict that idea.

Two independent studies are now considered to have solved the puzzle:
the Martian moons must have arisen from a giant collision 100 to 800
million years after the beginning of the planet's formation.
According to one study, the debris from the collision formed a very
large disc around Mars, made up of a dense inner part composed of
matter in fusion, and a very thin outer part primarily of gas. In the
inner part of the disc was formed a moon a thousand times the size of
Phobos, which has since disappeared. The gravitational interactions
created in the outer disc by that massive moon could have acted as a
catalyst for the gathering of debris to form other smaller, more
distant moons. After a few thousand years, Mars was surrounded by a
group of approximately ten small moons and one enormous one. A few
million years later, once the debris disc had dissipated, the tidal
effects of Mars brought most of the satellites back down onto the
planet, including the very large moon. Only the two most distant
small moons, Phobos and Deimos, remained.

In a second study, researchers ruled out the possibility of a capture
by statistical arguments based on the compositional diversity of the
asteroid belt. They show, moreover. that the spectra of Phobos and
Deimos are incompatible with that of the primordial matter that formed
Mars (meteorites such as ordinary chondrite, enstatite chondrite
and/or angrite). They therefore support the collision scenario. The
spectra indicate that the satellites are made of fine-grained dust
(smaller than a micrometre). Yet the very small size of grains on the
surface of Phobos and Deimos cannot, according to the researchers, be
solely explained as the consequence of erosion from bombardment by
interplanetary dust. That means (they say) that the satellites were
from the beginning made up of very fine grains, which can only form by
gas condensation in the outer part of the debris disc (and not from
the magma present in the inner part). Both studies are in agreement
on thar point. Moreover, the formation of Martian moons from very
fine grains could also be responsible for a high internal porosity,
which would explain their surprisingly low densities.

The theory of the giant collision, which is advanced by the two
independent studies, could explain why the northern hemisphere of Mars
has a lower altitude than the southern hemisphere: the Borealis basin
is most probably the site of a giant collision, such as the one that
gave birth to Phobos and Deimos. It also helps to explain why Mars
has two satellites instead of a single one like our Moon, which is
also supposed to have been created by a giant collision. The research
suggests that the satellite systems that were created depended on the
planet's rotational velocity, because at the relevant time the Earth
was rotating very quickly (in less than four hours), whereas Mars
turned six times more slowly. New observations will soon make it
possible to know more about the age and composition of the Martian
moons. Japan's space agency (JAXA) has decided to launch a mission in
2022, named Mars Moons Exploration (MMX), which will bring back
samples from Phobos in 2027. Their analysis could confirm or
invalidate the new proposal. ESA has planned a similar mission in
2024 in association with the Russian space agency (Roscosmos).

[YesNo]

It is good they have hypotheses test. I remember hearing, but don't know where that information came from, that the collision of the Earth with the other object that created the moon sent the Earth into its spin. Based on this it looks like the spin rate started earlier and was very fast and then slowed down.

[Dreamwoven]

SMALL ASTEROID IS THE EARTH'S CONSTANT COMPANION
NASA

A small asteroid has been discovered in an orbit around the Sun that
keeps it as a constant companion of the Earth, and it will remain so for
centuries to come. As it orbits the Sun, the new-found asteroid,
designated 2016 HO3, appears to circle around the Earth as well. It is
too distant to be considered a true satellite of our planet, but it is
the best and most stable example to date of a near-Earth companion.
Since 2016 HO3 loops around our planet, but never ventures very far away
as we both go round the Sun, we refer to it as a quasi-satellite of
Earth. One other asteroid -- 2003 YN107 -- followed a similar orbital
pattern for a while over 10 years ago, but it has since departed from
our vicinity. The new asteroid is much more locked onto us. Calcula-
tions indicate 2016 HO3 has been a stable quasi-satellite of the Earth
for almost a century. In its yearly orbit round the Sun, the asteroid
spends about half the time closer to the Sun than the Earth is, and
passes ahead of our planet, and the other half of the time farther away,
causing it to fall behind. Its orbit is also tilted a little, causing
it to pass up and then down once each year through the Earth's orbital
plane.

The asteroid's orbit also undergoes a slow, back-and-forth twist over
multiple decades. The asteroid's loops around the Earth drift a little
ahead or behind from year to year, but when they drift too far forward
or backward, the Earth's gravity is just strong enough to reverse the
drift and hold onto the asteroid so that it never wanders farther away
than about 100 times the distance of the Moon. The same effect also
prevents it from ever approaching much closer than about 38 times the
distance of the Moon. In effect, the small asteroid is caught in a
little dance with the Earth. Asteroid 2016 HO3 was first observed on
2016 April 27, by the Pan-STARRS 1 asteroid survey telescope in Hawaii.
The size of the object has not yet been firmly established, but it is
probably between 40 and 100 metres.

[YesNo]

It looks like the earth has a tiny moon we didn't know about.

[Dreamwoven]

Here is another astounding fact:

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 426 2016 July 17

DWARF PLANET MAKEMAKE HAS MOON
Southwest Research Institute

Scientists have discovered a dark moon orbiting Makemake, one of the
'big four' dwarf planets populating the Kuiper-Belt region at the edge
of the Solar System. The moon -- presently called MK2 -- is 1,300
times fainter than the dwarf planet. A nearly edge-on orbital
configuration helped it evade detection, placing it deep within the
glare of the icy dwarf during a substantial fraction of its orbit.
Makemake is one of the largest and brightest known Kuiper Belt Objects
(KBOs), second only to Pluto. The moon is probably less than 100
miles in diameter while Makemake itsef is about 870 miles across.
Discovered in 2005, Makemake is shaped like a football (notice that
this item was drafted in America, where footballs are not spheres) and
sheathed in frozen methane. With a moon, we can calculate Makemake's
mass and density and contrast the orbits and properties of the parent
dwarf and its moon, to understand the origin and history of the
system. We can compare Makemake and its moon to other systems, and
broaden our understanding of the processes that shaped the evolution
of the Solar System. With the discovery of MK2, all four of the
currently designated dwarf planets are known to have one or more
satellites. The fact that Makemake's satellite went unseen despite
previous searches suggests that other large KBOs may have hidden
moons. Before this discovery, the lack of a satellite for Makemake
suggested that it had not suffered a severe impact in the past. Now,
scientists will be looking at its density to determine whether it was
formed by a collision or whether it was grabbed by the parent dwarf's
gravity. The apparent ubiquity of moons orbiting KBO dwarf planets
supports the idea that collisions are a near-universal feature in the
histories of those distant objects.

[Pompey Bum]

It looks like the earth has a tiny moon we didn't know about.

So can we pretend to land on that one, too? ;-)

[YesNo]

So can we pretend to land on that one, too? ;-)

Well that one is rather small and it might not stick around.

[Pompey Bum]

Yes, but could we fake not going there?

[YesNo]

We could pretend it's the planet where le petit prince came from. Being only 100 meters in size where size is what? Diameter or circumference?

[Pompey Bum]

Be my guest, YN. Once the pretending begins, why should the sky be an obstacle?

[YesNo]

That's how I look at the pretend manned Moon landings of the early 1970s. Land one of them and you might as well land another handful of them in rapid order.

[Pompey Bum]

So why should faking this little moon be any harder? Surely fake rocket telemetry has only improved since 1969?

[desiresjab]

Interesting about the near earth companion. Wise money has to go down on the side that says it is only a matter of time before our observations and calculations uncover cosmic calamity waiting for us that is still decades away. We will have time to act like fools.

Our solar system orbits the galaxy every 200,000 years. There could be a lot of "strange" space ahead of us. At least there will be a different view in 100,000 years. I can't wait.

[YesNo]

I think it is more difficult to fake a moon landing today because of improved technology. Also there is no political reason to do so.

Regarding having a different view 100,000 years from now, aren't all the objects in the solar system and our portion of the galaxy coming along with us as we circle the galaxy?

[Pompey Bum]

I think it is more difficult to fake a moon landing today because of improved technology. Also there is no political reason to do so.

Well, I sure don't want Chinese faking getting ahead of ours.

[YesNo]

The fact that information can be faked requires skepticism as well as skepticism against skepticism. It is usually good to ask why someone wants you to believe something. Do they have a political, metaphysical or religious position they want to promote? If so, focus on that. Are they trying to sell you a stock? Are they trying to distort their country's gross domestic product to keep investors happy. Are they trying to claim there are weapons of mass destruction to get their people demanding a war of intervention?

What impresses me about the links that Dreamwoven provides in this thread is how little we know about the universe. Sure, we know simple things, as well as we can know them, such as the microwave background, because there is little there to know, but we are not aware of the objects in our solar system let alone the immediate region of our galaxy.

[Dreamwoven]

Thank you YesNo, much good sense.

[Dreamwoven]

http://earthsky.org/space/protoplanet-blasted-out-mare-imbrium

There are lots of large asteroid blasts on the moon and other rocky planets. This is one that has been discussed.

[Pompey Bum]

The fact that information can be faked requires skepticism as well as skepticism against skepticism. It is usually good to ask why someone wants you to believe something. Do they have a political, metaphysical or religious position they want to promote? If so, focus on that. Are they trying to sell you a stock? Are they trying to distort their country's gross domestic product to keep investors happy. Are they trying to claim there are weapons of mass destruction to get their people demanding a war of intervention?

Good point, YN. If I'd have known how much money my oncologist would made off of my cancer treatment, I never would have let her talk me into it. If only I'd had your advice then...

[YesNo]

Good point, YN. If I'd have known how much money my oncologist would made off of my cancer treatment, I never would have let her talk me into it. If only I'd had your advice then...

I don't see what this has to do with an astronomy thread.

[Pompey Bum]

I don't see what this has to do with an astronomy thread.

You're the one who brought it up.

[YesNo]

http://earthsky.org/space/protoplanet-blasted-out-mare-imbrium

There are lots of large asteroid blasts on the moon and other rocky planets. This is one that has been discussed.

I had not considered the Mare Imbrium to have been originally made by an impact, but it does look circular. After that impact I assume there was a lava flow of some sort.

[Dreamwoven]

That is something I haven't considered. The moon has no atmosphere so there is no resistance on entry. In that case there would be no lava flow. The impact crater might generate enough heat to create a lava flow, though. I think this needs a lot of further thought and analysis.

[desiresjab]

N=R*x fp x ne x fl x fi x fc x L

Has this ever been discussed, and is it suitable for this thread?

[YesNo]

N=R*x fp x ne x fl x fi x fc x L

Has this ever been discussed, and is it suitable for this thread?

I don't know what this relationship is meant to represent.

Regarding the lava flow, one would have an impact crater on an active planet. Sometime later the depression of the crater would be filled with lava. https://en.wikipedia.org/wiki/Lunar_mare

[Dreamwoven]

http://www.space.com/33494-nearby-earth-size-exoplanets-rocky.html

This page from the Space website shows Hubble still gathering useful info:

[Dreamwoven]

Thanks, Patty.

I have been thinking of all those astronomy-interested who invest in telescopes and equipment. But we have our own moon which can be examined without any aids at all. And it is always there visible to every part of the world. This post looks at one aspect of the moon: http://www.space.com/33491-mysterious-moon-grooves-protoplanet-impact.html?.

[YesNo]

I didn't notice the Imbrium Sculpture before, but now that I think of Mare Imbrium being the result of a collision it seems obvious.

[Dreamwoven]

Now that the probe called Juno is in orbit around Jupiter we are already starting to get more information on that huge planet: http://www.space.com/33551-jupiter-heats-up-great-red-spot.html.

[tailor STATELY]

So strange the amount of heat from the Great Red Spot. Perhaps vortices above a super-super-super volcano ?, but that wouldn't account for an acoustical component... Can't wait to find out !

Ta ! (short for tarradiddle),
tailor STATELY

[YesNo]

Now I know there exist things like gravity and acoustic waves and the upward coupling of the lower and higher atmosphere assuming these explanations are correct.

[Dreamwoven]

So strange the amount of heat from the Great Red Spot. Perhaps vortices above a super-super-super volcano ?, but that wouldn't account for an acoustical component... Can't wait to find out !

Ta ! (short for tarradiddle),
tailor STATELY

Yes and this at the start of the Juno Mission!

[Dreamwoven]

http://earthsky.org/space/where-are-ceres-large-craters ?

[Dreamwoven]

I'm not convinced by the arguments in the link of the previous post. We all know that the larger the object the more likely it will capture meteorites, in part by its much greater gravitational pull. This is why the big outer planets have many moons and why Jupiter sucks to it larger meteorites. A small dwarf planet, without even a moon, will have a relatively quiet and calm history. Nothing strange about that.

[desiresjab]

What I most expect and predict as the connundrum is failure of the model to accurately reflect the personal history of each asteroid. No surprise at all, since their lives do not look to have been so quiet to me. Belts still have thickness. An interior portion is hit by less debris, certainly by fewer large chunks hurling in from outside the belt. This, as well, means fewer big collisions on these interior bodies of the belt. I have to assume these scientists are top guns and have already considered all this and more, which would make the solar flyby coming up quite exciting to them.

[Dreamwoven]

Here is a double-double star: http://earthsky.org/brightest-stars/epsilon-lyrae-the-famous-double-double-star

Apparently they can be seen with binoculars!

[YesNo]

I've noticed Vega before in the constellation Lyra, but I didn't realize there were double double stars like Epsilon Lyrae.

[Dreamwoven]

This item in EarthSky was published today: http://earthsky.org/space/star-lashes-companion-with-mystery-ray.

No idea what they mean by pulsing neutron star.

[tailor STATELY]

Pulsar... https://en.wikipedia.org/wiki/Pulsar

[YesNo]

It puzzles me why the radiation is not global over the pulsar but localized like a light in a lighthouse that rotates the beam.

[Dreamwoven]

I am afraid I don't understand what pulsars are, and I have read the wikipedia item on it.

[tailor STATELY]

See the wiki picture of the magnetic alignment of the beam... then consider the misalignment theory (underlined below) (think wobble) that causes the pulse... rather than being exactly straight on, both magnetic and rotational axes perfectly in line with each other in direction, to the observer where the energy would be in constant view - which is theoretically possible for other systems.

"The events leading to the formation of a pulsar begin when the core of a massive star is compressed during a supernova, which collapses into a neutron star. The neutron star retains most of its angular momentum, and since it has only a tiny fraction of its progenitor's radius (and therefore its moment of inertia is sharply reduced), it is formed with very high rotation speed. A beam of radiation is emitted along the magnetic axis of the pulsar, which spins along with the rotation of the neutron star. The magnetic axis of the pulsar determines the direction of the electromagnetic beam, with the magnetic axis not necessarily being the same as its rotational axis. This misalignment causes the beam to be seen once for every rotation of the neutron star, which leads to the "pulsed" nature of its appearance. The beam originates from the rotational energy of the neutron star, which generates an electrical field from the movement of the very strong magnetic field, resulting in the acceleration of protons and electrons on the star surface and the creation of an electromagnetic beam emanating from the poles of the magnetic field."

Ta ! (short for tarradiddle),
tailor STATELY

[desiresjab]

See the wiki picture of the magnetic alignment of the beam... then consider the misalignment theory (underlined below) (think wobble) that causes the pulse... rather than being exactly straight on, both magnetic and rotational axes perfectly in line with each other in direction, to the observer where the energy would be in constant view - which is theoretically possible for other systems.

"The events leading to the formation of a pulsar begin when the core of a massive star is compressed during a supernova, which collapses into a neutron star. The neutron star retains most of its angular momentum, and since it has only a tiny fraction of its progenitor's radius (and therefore its moment of inertia is sharply reduced), it is formed with very high rotation speed. A beam of radiation is emitted along the magnetic axis of the pulsar, which spins along with the rotation of the neutron star. The magnetic axis of the pulsar determines the direction of the electromagnetic beam, with the magnetic axis not necessarily being the same as its rotational axis. This misalignment causes the beam to be seen once for every rotation of the neutron star, which leads to the "pulsed" nature of its appearance. The beam originates from the rotational energy of the neutron star, which generates an electrical field from the movement of the very strong magnetic field, resulting in the acceleration of protons and electrons on the star surface and the creation of an electromagnetic beam emanating from the poles of the magnetic field."

Ta ! (short for tarradiddle),
tailor STATELY

A good explanation. It is mere happenstance if their magnetic poles are at right angles to their spin, which is the only time we would see one of them appear to be on all the time, if the line through its magnetic poles pointed straight at us.

Concerning planets with molten magnetic cores, their spin has something to do with where the magnetic poles are, I believe. Probably no one knows why the magnetic poles are where they are in a pulsar. I do not anyway. Perhaps they are vestigial.

[Dreamwoven]

Thanks for that clear explanation, tailor. It was in the wikipedia item, but made much clearer by your description.

[desiresjab]

The revolutions per minute of most neutron stars being what they are, any with rpm faster than 30 per second will indeed appear to be on all the time to a naked eye through a telescope. Most spin many times that rate, requiring delicate instruments to determine there is a period at all.

[Dreamwoven]

This 5 minute video shows how difficult it was to land a rover (Curiosity) on the surface of a
Mars: http://earthsky.org/space/mars-curiosity-rovers-seven-minutes-of-terror so it was fit to explore.

[desiresjab]

This 5 minute video shows how difficult it was to land a rover (Curiosity) on the surface of a
Mars: http://earthsky.org/space/mars-curiosity-rovers-seven-minutes-of-terror so it was fit to explore.

Wow, what a dance that was.

[Dreamwoven]

A couple of items on the asteroid belt. It lies between Mars and Jupiter.

http://www.universetoday.com/130231/long-take-get-asteroid-belt/

http://www.universetoday.com/130136/far-asteroid-belt-earth/

[Dreamwoven]

A couple of items on the asteroid belt. It lies between Mars and Jupiter.

http://www.universetoday.com/130231/long-take-get-asteroid-belt/

http://www.universetoday.com/130136/far-asteroid-belt-earth/

[YesNo]

I think the theoretical EM Drive is the most interesting way to get to the asteroid belt. However, I don't think we would be able to send humans there, so robotics would have to also advance before it is feasible to mine on the asteroids.

[Dreamwoven]

The Universe Today published an article on how many moons there are in the solar system. You can read the article here: http://www.universetoday.com/15516/how-many-moons-are-in-the-solar-system/. The question is not as simple as one might think...

[Dreamwoven]

Earth-like planet discovered around Proxima Centauri: http://www.universetoday.com/130276/earth-like-planet-around-proxima-centauri-discovered/

[YesNo]

Having an Earth-like exoplanet so close is good news. The article mentioned that the data is at the limit of current measurement abilities. So before sending a nanocraft there we need to improve our ability to measure what is out there.

[Dreamwoven]

Another contribution from Journal of Popular Astronomy:

NEW DISTANT DWARF PLANET BEYOND NEPTUNE
University of British Columbia

Astronomers have discovered a new dwarf planet orbiting in the disc of
small icy bodies beyond Neptune. The new object is about 700 km in
diameter and has one of the largest orbits for a dwarf planet.
Designated 2015 RR245 by the International Astronomical Union's Minor
Planet Center, it was found with the Canada-France-Hawaii Telescope on
Mauna Kea, Hawaii, as part of the ongoing 'Outer Solar System Origins
Survey' (OSSOS). The OSSOS project uses computers to hunt for the
images, and the team was presented with a bright object moving at such a
slow rate that it was clearly at least 120 times further from the Sun
than the Earth. The size of RR245 is not yet exactly known, as its
surface properties need further measurement. The vast majority of dwarf
planets like RR245 were destroyed or thrown from the Solar System as the
giant planets moved out to their present positions. RR245 is one of the
few that survived to the present day, along with Pluto and Eris, the
largest known dwarf planets. RR245 now circles the Sun among the remnant
population of tens of thousands of much smaller trans-Neptunian bodies,
most of which orbit unseen. RR245 has been on its highly eccentric orbit
for at least the last 100 million years. After hundreds of years further
than 80 astronomical units (AU) from the Sun, RR245 is travelling towards
its closest approach at five billion km (34 AU), which it will reach
around 2096. As RR245 has been observed for only one of the 700 years it
takes to orbit the Sun, where it came from and how its orbit will slowly
evolve in the far future is unknown. Its precise orbit will be refined
over the coming years, after which RR245 will be given a name. As
discoverers, the OSSOS team can submit their preferred name for RR245 to
the International Astronomical Union for consideration. RR245 is the
largest discovery and the only dwarf planet found by OSSOS, which has
discovered more than five hundred new trans-Neptunian objects.

This will take 700 years to orbit the sun. Planet 9 a giant planet which would orbit the sun in 10,000 to 20,000 years, looks increasingly unlikely.

[YesNo]

Pluto is about 2370 km in diameter: http://www.space.com/18568-how-big-is-pluto.html So 700 km is pretty small.

This could be on the lower edge of what constitutes a dwarf planet although having enough gravity to have a spheroidal shape is what counts: https://www.spaceanswers.com/solar-system/how-big-is-a-dwarf-planet/

[Dreamwoven]

That's true, YesNo. Many are still smarting from the demotion of Pluto from a planet to a dwarf planet. Ceres is also a dwarf planet, spheroid, but without any moons of its own, unlike Pluto.

[Dreamwoven]

Cassini is still orbiting the only moon (Saturn's Titan) with extensive regions of open seas. See http://earthsky.org/space/saturns-moon-titan-has-flooded-canyons

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 427 2016 August 14

Also has a post on the above,more detailed. Copied it below:

CASSINI FINDS FLOODED CANYONS ON TITAN
NASA

The Cassini spacecraft has found, on Saturn's large moon Titan, deep,
steep-sided canyons that are flooded with liquid hydrocarbons. The
finding represents the first direct evidence of the presence of liquid-
filled channels on Titan, as well as the first observation of canyons
hundreds of metres deep. The Cassini observations reveal that the
channels -- in particular, a network of them named Vid Flumina -- are
narrow canyons, generally a bit less than a kilometre wide, with slopes
steeper than 40 degrees. The canyons also are quite deep -- those
measured are 240 to 570 metres from top to bottom. The branching
channels appear dark in radar images, much like Titan's methane-rich
seas. That suggested to scientists that the channels might also be
filled with liquid, but a direct detection had not been made until now.
Previously it was not clear if the dark material was liquid or merely
saturated sediment -- which at Titan's frigid temperatures would be made
of ice, not rock. Cassini's radar is often used as an imager, providing
a window to see through the dense haze that surrounds Titan to reveal the
surface below. But during a recent pass, the radar was used as an
altimeter, sending pings of radio waves to the moon's surface to measure
the height of features there. The researchers combined the altimetry
data with previous radar images of the region to make their discovery.

The key to understanding the nature of the channels was the way Cassini's
radar signal reflected off the bottoms of the features. The radar
instrument observed a glint, indicating an extremely smooth surface like
that observed from Titan's hydrocarbon seas. The timing of the radar
echoes, as they bounced off the canyons' edges and floors, provided
direct measures of their depths. The presence of such deep cuts in the
landscape indicates that whatever process created them was active for a
long time or eroded down much faster than in other areas of Titan's
surface. The researchers' proposed scenarios include uplift of the
'terrain' and changes in sea level, probably both. It is likely that a
combination of those processes led to the formation of the deep canyons,
but it is not clear to what degree each was involved. What is clear is
that any description of Titan's evolution needs to be able to explain how
the canyons got there. Terrestrial examples of both of those types of
canyon-carving processes are found along the Colorado River in Arizona.
An example of uplift powering erosion is the Grand Canyon, where the
terrain's rising altitude caused the river to cut deeply downward into
the landscape over the course of several million years. For canyon
formation driven by variations in water level, look to Lake Powell. When
the water level in the reservoir drops, it increases the river's rate of
erosion. While the altimeter data also showed that the liquid in some of
the canyons around Ligeia Mare is at sea level -- the same altitude as
the liquid in the sea itself -- in others it sits tens of metres higher
in elevation. The researchers interpret the latter to be tributaries
that drain into the main channels below. Future work will extend the
methods used in this study to all the other channels that Cassini's radar
altimeter has observed on Titan. The researchers expect their continued
work to produce a more comprehensive understanding of forces that have
shaped Titan's landscape.

[YesNo]

It is interesting that the terrain needs to rise as the water erodes the surface for the canyons to get as deep as they are. That sort of makes sense. I normally think of the process as just the effect of water rather than the rising ground.

[desiresjab]

It is interesting that the terrain needs to rise as the water erodes the surface for the canyons to get as deep as they are. That sort of makes sense. I normally think of the process as just the effect of water rather than the rising ground.

What would happen if the fluid keeps digging but the ground does not rise?

[YesNo]

What would happen if the fluid keeps digging but the ground does not rise?

It would take a longer time to dig the same size hole because more ground further along the water way would have to be moved out of the way.

[Dreamwoven]

http://earthsky.org/brightest-stars/deneb-among-the-farthest-stars-to-be-seen

[YesNo]

I remember watching Deneb as the Swan constellation descended into the waters of Green Bay last autumn. I was sheltered by a warm cabin and with a large window facing south-west. Nice sunsets as well.

What amazes me is the margin of error reported in the article. Deneb could be between 1425 and 7000 light years away. That means that other estimates, including those about its size, should have similar ranges.

[Dreamwoven]

Yes, that comment struck me too. They are vast ranges. How much else is that far out in terms of estimated distances? I mean 1,425 light years versus 7,000 light years.

[Dreamwoven]

http://www.universetoday.com/130357/europa-clipper-team-braces-for-bad-news/

It looks as if the latest proposals to investigate the moon of Saturn with liquid seas (the probe Europa Clipper) may not get funding. It looks to be an interesting project.

[YesNo]

Europa is more interesting as a source of life than other places. It would be nice to find living organisms there that are not related to those on Earth. I was hoping they might have found evidence of life on Mars, but I haven't heard of anything.

Still, being forced to keep to a tighter budget may be a good thing in the long run. That could lead to new technologies allowing more missions to be sent for the same cost.

[Dreamwoven]

Another idea is the possibility of a dyson sphere to collect the energy from a sun/star. See http://earthsky.org/space/tabbys-star-more-weirdness. So called out of a science fiction book: https://en.wikipedia.org/wiki/Dyson_sphere. Interesting discussion, still unresolved...

[Dreamwoven]

spectacular conjunctions in the sky at the moment:
http://www.universetoday.com/130283/5-days-2-spectacular-conjunctions/

[YesNo]

On Google Star Map, I see Mercury, Venus and Jupiter should be close together along with Saturn and Mars in a different portion of the sky. I'll have to pay attention tonight.

[Dreamwoven]

http://www.space.com/33780-could-proxima-centauri-be-our-interstellar-getaway.html.

Couple of links, too:

http://www.seeker.com/earth-like-planets-may-be-nothing-like-earth-1765666978.html#news.discovery.com

http://www.seeker.com/interstellar-travel-is-hard-why-bother-1765960258.html

http://www.seeker.com/icarus-interstellar-visions-of-our-starship-future-1769714561.html

http://www.seeker.com/firefly-starship-to-blaze-a-trail-to-alpha-centauri-1769538313.html

[YesNo]

I like the idea of those tiny probes that ride laser beams the best, but I don't see why we would want to send humans there. Robot technology needs to get better than it is. Come to think of it I don't understand why we aren't contemplating going to the Moon to practice new technologies rather than thinking about manned landing on asteroids. Even there I don't see why humans need to be the ones going to those places.

What we need to find is not just an Earth-like planet, but one that suggests there already is life on the planet. As the second article you linked to mentioned, we don't even know if those current Earth-like candidates are really Earth-like.

[Dreamwoven]

No, its true, the technology is not there yet, it is a long way away still. That's my feeling too.

[Dreamwoven]

http://www.universetoday.com/130419/eso-announcement-address-reports-proxima-centauri-exoplanet/

The above link deals with the chance that an earth-like planet is orbiting the nearest star to our own (Proxima Centauri). A statement will be made from the European Southern Observatoryhttp://www.eso.org/public/about-eso/esoglance/ around midday today.

[YesNo]

It looks like the ESO confirmed the planet's discovery: http://futurism.com/eso-confirms-earth-sized-planet-found-around-the-closest-star-to-earth-proxima-centauri/

[Dreamwoven]

Great, well done YesNo. The link to the ESO post itself finally came out yesterday evening after I logged off:
http://www.universetoday.com/130427/habitable-terrestrial-exoplanet-confirmed-around-nearest-star/

[Dreamwoven]

There are risks in long-distance space journeys made by tiny sail propulsion. This post in Universe Today discusses them:

http://www.universetoday.com/130458/shields-mr-sulu-cruising-20-speed-light-inherent-risks/

[Dreamwoven]

Something else I have been questioning is the description of a planet as "earth-like". It just means rocky and that it is within the habitable zone in terms of distance from its sun: http://www.universetoday.com/130469/earthlike-even-mean-apply-proxima-centauri-b/.

We also have only "life on earth" as a yardstick.

Of course it is encouraging that Proxima Centauri b does fulfil the basic criteria, but then so does Mars...

[Iain Sparrow]

Something else I have been questioning is the description of a planet as "earth-like". It just means rocky and that it is within the habitable zone in terms of distance from its sun: http://www.universetoday.com/130469/earthlike-even-mean-apply-proxima-centauri-b/.

We also have only "life on earth" as a yardstick.

Of course it is encouraging that Proxima Centauri b does fulfil the basic criteria, but then so does Mars...

The problem with Proxima Centauri, among other things, is that it periodically flares, and unless I'm mistaken is part of a distant binary star system... most people don't understand just how unlikely Life is, even on our extremely "earth-like" planet. Any solar system that falls short of our rather amazing circumstances, would be hard pressed to support higher lifeforms.
Also consider, when our sun was much younger and burned cooler, it was Venus that was in that habitable "goldilocks zone".

[Iain Sparrow]

Something else I have been questioning is the description of a planet as "earth-like". It just means rocky and that it is within the habitable zone in terms of distance from its sun: http://www.universetoday.com/130469/earthlike-even-mean-apply-proxima-centauri-b/.

We also have only "life on earth" as a yardstick.

Of course it is encouraging that Proxima Centauri b does fulfil the basic criteria, but then so does Mars...

The problem with Proxima Centauri, among other things, is that it periodically flares, and unless I'm mistaken is part of a distant binary star system... most people don't understand just how unlikely Life is, even on our extremely "earth-like" planet. Any solar system that falls short of our rather amazing circumstances, would be hard pressed to support higher lifeforms.
Also consider, when our sun was much younger and burned cooler, it was Venus that was in that habitable "goldilocks zone".

[YesNo]

There are risks in long-distance space journeys made by tiny sail propulsion. This post in Universe Today discusses them:

http://www.universetoday.com/130458/shields-mr-sulu-cruising-20-speed-light-inherent-risks/

The small sails still seem like something worth exploring. They should try to go to the Moon first. I wonder what kind of information such a small craft could actually provide.

Regarding life on that new exoplanet I expect they will find life on Europa first under the ice layer or on some other object in our solar system. But until one finds an example we still have the possibility that life only occurred on Earth.

[Dreamwoven]

The problem with Proxima Centauri, among other things, is that it periodically flares, and unless I'm mistaken is part of a distant binary star system... most people don't understand just how unlikely Life is, even on our extremely "earth-like" planet. Any solar system that falls short of our rather amazing circumstances, would be hard pressed to support higher lifeforms.
Also consider, when our sun was much younger and burned cooler, it was Venus that was in that habitable "goldilocks zone".

I didn't know Proxima Centauri is a flare star (https://en.wikipedia.org/wiki/Flare_star). I hadn't thought of that as a dimension to consider, Iain.

[Dreamwoven]

Something I leaned today was what a lagrange point (https://en.wikipedia.org/wiki/Lagrangian_point) was, and how useful it can be for space exploration. I got it from here: http://www.universetoday.com/102785/what-are-lagrange-points/. The James Webb space telescope will be placed at one of these.

[YesNo]

I can intuitively see why there are Lagrange points at L1, L2 and L3. It surprises me that there are also Lagrange points at L4 and L5, but they are the most stable ones. I wonder why there aren't Lagrange points elsewhere.

I finished a book of essays called "What is Consciousness?". I don't recommend it, but one of the essays discussed the "holographic theory of the universe". The idea is that our universe is a 3D projection from a 2D region outside or on the edge of the universe. It didn't make a lot of sense and apparently there is now evidence against it: http://blogs.discovermagazine.com/d-brief/2015/12/08/reality-check-the-universe-is-probably-not-a-hologram/#.V8MUkpgrLIU

But failed theories are also useful. The tools and experience used to build those experiments can be put to other uses.

[Dreamwoven]

That was a good idea, YesNo. Weird to conceive of space as a hologram...

The latest issue of Popular Astronomy (p. 5) has an interesting article on Gravitational Waves by Melanie Davies on LISA Pathfinder (a collaborative mission with the European Space Agency). The LISA Space Observatory is due to be launched in 2034 and consisting of a three-spacecraft constellation with arm-lengths of a million kilometres using laser interferometry between the satellites able to detect thousands of gravitational wave sources. It will supplement existing signal detection for ground-based gravitational wave observatories like LIGO (https://en.wikipedia.org/wiki/LIGO).

[Dreamwoven]

This was an interesting article on the possible existence of a large Plant 9 with an orbit around the sun, but very far out, in the Oort Cloud.:
http://www.universetoday.com/130524/planet-9-search-turning-wealth-new-objects/.

We are still puzzled over what is in orbit around our own sun...

This is an interesting article on how difficult it is to know such a seemingly simple fact.

[YesNo]

At least they are able to increasingly narrow down the possible location of planet 9. It also makes me wonder about dark matter. That is based on gravitational effects. If enough objects are found in the Oort Cloud would that disprove the existence of dark matter in our solar system?

[Dreamwoven]

An interesting piece on Mars and one of its moons, Phobos:

http://www.universetoday.com/130544/origin-phobos-groovy-mystery/

[Iain Sparrow]

At least they are able to increasingly narrow down the possible location of planet 9. It also makes me wonder about dark matter. That is based on gravitational effects. If enough objects are found in the Oort Cloud would that disprove the existence of dark matter in our solar system?


It would not prove or disprove either the existence of, or influence of Dark Matter on our solar system.
The theory that seems to be gaining traction lately, is that Dark Matter coalesces in the central plain of spiral galaxies, like our Milky Way. And that our galaxy periodically passes through, or brushes this Dark Matter disk, roughly every 30 million years. Andromeda, our sister galaxy exhibits both rotational irregularities, and debris clusters that seem to support the Dark Matter Disk theory... but let's face it, they simply don't know. Some scientists are linking this 30 million year cycle with mass extinction events on Earth, which to me is just too convenient.

[YesNo]

I don't understand the speculations about dark matter well enough to know whether I would find them plausible or not, however, I would like to know more, but getting off my butt to find out is another matter. Having dark matter coalesce seems puzzling. If it can coalesce, why doesn't it coalesce into a planet like ordinary matter? Sometimes I wonder if the supposed existence of dark matter could be explained away by assuming that big-G, the gravitational "constant", is not constant. That set of spacecrafts designed to detect gravitation waves will hopefully give some answers.

[Dreamwoven]

I have to confess that I find the debates over dark matter very hard to grasp. Or perhaps it is just too complex for those who are not in the know on this.

[YesNo]

It occurred to me that saying that big-G is not constant, as I suggested earlier, doesn't help a lot. It may explain the mathematical anomalies about gravitation, but it opens up other questions: Why is big-G not constant? What makes it change? The change will not likely be "random", meaning that one doesn't have to explain it. The change will vary enough beyond the random that some explanation of that non-random change will be required as well.

Saying something is a constant is more or less a claim that we (hopefully) don't have to explore that part of reality any further.

[Dreamwoven]

I don't think we know enough yet about what dark matter is, never mind how it works.

See this link on the Spitzer Space Telescope: http://www.nasa.gov/feature/goddard/2016/nasa-scientist-suggests-possible-link-between-primordial-black-holes-and-dark-matter

[YesNo]

Any form of non-randomness or non-uniformity can be viewed as structure that requires explanation as that shown in the CIB in your link. It is interesting that dark matter could be explained by the existence of many black holes formed during the first second of the existence of the universe.

The claim that the model fit the data was "surprisingly good" makes me wonder how good was the fit. I interpret it as meaning only that the fit was good enough that the model could not be rejected at the moment.

[Dreamwoven]

The first pictures of the north pole of Jupiter from Juno at a height of 2,500 miles: http://www.universetoday.com/130608/juno-captures-jupiters-enthralling-poles-2500-miles/

This is the first of Juno's 30 or more orbits.

[YesNo]

It was interesting that the auroras were considered "noisy". I had not thought that was a feature that distinguished them even though they would not be audible to us without being shifted into our audible range.

[Dreamwoven]

Universe Today is a website I have come to use a lot. Just discovered a whole series of posts on colonising the nearby planets. I have to admit I react negatively to the idea of humankind spreading pollution and industry to our neighbouring planets and even the moon: http://www.universetoday.com/130482/how-do-we-colonize-venus/. But perhaps it will happen as we exhaust more and more resources on Earth.

[YesNo]

I don't see why we would want to send human beings into outer space. Computers will soon be driving our cars. Let them go and collect the data or resources we need.

However, the idea of terraforming Venus gave me an idea. What if we could find a way to move Venus into the habitable zone? Then the environment could be cleaned up (by robots). That technology would be something we could use to keep Earth in the habitable zone as well. I know moving the orbit of Venus into the habitable zone sounds ridiculous, but it would make Venus closer to Earth than it is now and easier to get to.

And then we have the Moon. It is located in the habitable zone already, but it needs a magnetosphere to protect it from radiation.

[desiresjab]

I don't see why we would want to send human beings into outer space. Computers will soon be driving our cars. Let them go and collect the data or resources we need.

However, the idea of terraforming Venus gave me an idea. What if we could find a way to move Venus into the habitable zone? Then the environment could be cleaned up (by robots). That technology would be something we could use to keep Earth in the habitable zone as well. I know moving the orbit of Venus into the habitable zone sounds ridiculous, but it would make Venus closer to Earth than it is now and easier to get to.

And then we have the Moon. It is located in the habitable zone already, but it needs a magnetosphere to protect it from radiation.

If we whistle loud enough, perhaps it will come.

[desiresjab]

Universe Today is a website I have come to use a lot. Just discovered a whole series of posts on colonising the nearby planets. I have to admit I react negatively to the idea of humankind spreading pollution and industry to our neighbouring planets and even the moon: http://www.universetoday.com/130482/how-do-we-colonize-venus/. But perhaps it will happen as we exhaust more and more resources on Earth.

I don't know why the thought bothers you at all. Pollution generated on the moon would do nothing but dissipate into space. On the other planets, it is not as if any livable environment is being messed up. Everyone on those planets will be living under a bubble anyway.

If you are worried about polluting planets after we terraform them, that seems even less appropriate. By the time we have conquered terraforming we should easily have conquered pollution. I think your objection is more aesthetic than rational. It has more to do with our poor record in the past than a real liklihood that we will still be polluting our environments in a future distant enough that terraforming is possible.

[Dreamwoven]

It won't happen in my lifetime anyway *shrugs*.

[Dreamwoven]

I don't see why we would want to send human beings into outer space. Computers will soon be driving our cars. Let them go and collect the data or resources we need.

However, the idea of terraforming Venus gave me an idea. What if we could find a way to move Venus into the habitable zone? Then the environment could be cleaned up (by robots). That technology would be something we could use to keep Earth in the habitable zone as well. I know moving the orbit of Venus into the habitable zone sounds ridiculous, but it would make Venus closer to Earth than it is now and easier to get to.

And then we have the Moon. It is located in the habitable zone already, but it needs a magnetosphere to protect it from radiation.

I think Venus is also in the habitable zone, the Goldilocks zone. Anyway, the kind of changes you suggest are way beyond the technology we have, or even likely to have, moving planets around like that.

[YesNo]

I checked this site: http://hzgallery.org/venus.html

It looks like Venus is in the habitable zone where surface water is in liquid form. However, it is also in a "Venus zone" where a runaway greenhouse effect occurs. It looks like we are not currently able to distinguish exoplanets in the habitable zone from those that are also in the Venus zone.

I agree that we can't move planets further or nearer the Sun, but I don't think we can terraform them either with current technology. I remember an old Flash Gordon show where Emperor Ming was moving his planet closer to Earth for some devilish reason. That may be as close as we get to moving planets around.

[Dreamwoven]

http://www.universetoday.com/130560/new-horizons-spies-plutos-neighbor-quaoar/

[YesNo]

So Quaoar is pronounced “Kwa-war”.

I was thinking more about terraforming Venus. Perhaps we could leave the planet where it is, but put an umbrella of satellites between it and the Sun. The satellites would block out some of the Sun's radiation and perhaps use that radiation for energy to terraform Venus. This way we would also be ready when the Earth entered the Venus zone. We could practice on the Moon.

[Dreamwoven]

http://www.universetoday.com/130710/osiris-rex-blasts-off-on-7-year-sampling-trek-to-asteroid-bennu-and-back/

Samples of an asteroid will be collected and brought back for analysis. Should learn something of the origins of Earth.

[prendrelemick]

At least they are able to increasingly narrow down the possible location of planet 9. It also makes me wonder about dark matter. That is based on gravitational effects. If enough objects are found in the Oort Cloud would that disprove the existence of dark matter in our solar system?

The problem is that to create enough baryonic matter to hold things together, would need a great deal more stars than there are, or have been. Remember heavier elements that make rocky debris are created in extremely large, hot stars in the first place. The amount of stars needed would shine across the universe (from our past) and light up the night sky.

Also, the models that are built on a non constant gravitational effect do not predict the universe we have. A mass that interacts only with gravity does (what ever it is.)

The Link below is a lecture by Carolin Crawford that looks at the ever evolving evidence for dark matter, a story of different scientific fields arriving at similar conclusions.

http://www.gresham.ac.uk/lectures-and-events/the-search-for-dark-matter

[YesNo]

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.

[Dreamwoven]

These two posts hint at the likelihood of running water on Mars (http://www.universetoday.com/130698/curiosity-rovers-proximity-possible-water-raises-planetary-protection-concerns/) and more exotic combinations on the ice giants - Neptune and Uranus (http://www.universetoday.com/130666/uranus-neptune-may-keep-hitlers-acid-stable-massive-pressure/).