Astronomy

Quote:

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Originally Posted by Dreamwoven

Tardigrades are tiny, under 0.5 of a millimetre long: https://en.wikipedia.org/wiki/Tardigrade. They are very tough, so they can likely survive anywhere. How much wiser would we be if their presence were confirmed on other planets/moons? Unless also other animals were discovered there as well...

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I think they are more developed forms of life than bacterias:

"Tardigrades are strangely adorable microscopic creatures that are capable of withstanding some of the worst that nature can throw at them. Classified as “extremophiles,” they can survive freezing, total dehydration, radiation, and even the vacuum of space. Tardigrades are an ancient species that diverged from ancestral animals back in the pre-Cambrian period (~600 million years ago), and likely evolved their own unique genes over a protracted period of time.

Earlier this year, scientists successfully revived a tardigrade that had been frozen solid for more than three decades—a new record for this durable species. Needless to say, scientists are understandably curious about tardigrades; research into these ancient creatures could tell us something about alien life on other planets, and how we might be able to leverage tardigrade biology in medicine and genetics."

https://gizmodo.com/genes-hold-the-k...ity-1786814698

Yes, but is not that very point we are discussing? Yes, if there are more developed species also in those waters but not otherwise.

What I mean is that the tardigrades,even if they are small, are complex organisms. I suppose the initial expectation of the scientists is to discover more simple forms of life. But in fact one doesn´t have any idea, what forms of life may be discovered.

No, I guess that is so. Looking at specific examples, where would the best place to look be? Saturn is a bit far away, but Enceladus is one moon that is promising. I believe there are plans to return there and investigate. Otherwise there are planets and moons around Jupiter: https://en.wikipedia.org/wiki/Europa_(moon)#Exploration.

Plans are in a very preliminary phase, so that limits discussion of them. What ideas do you have for future exploration?

I don´t know, as you say, we are still in a very preliminary phase, with researches heading in several directions. I think the scientists themselves will probably surprised with unexpected findings but when and where is difficult to predict.

There is really very little new in astronomy. According to EarthSky it should be possible to see the planet Saturn near the horizon. Its been overcast for more than week, so I can't check that out.

I have no idea what Saturn looks like or I would check from my location, in spite of all the sky scrapers that surround me.

Now this must be of global interest:

An all-new weather prediction system is on its way
"NASA and the National Oceanic and Atmospheric Administration have teamed up to increase the accuracy of weather forecasts down on Earth.
The Joint Polar Satellite System-1 (JPSS-1), the first of the series to be launched, was sent into space at the Vandenberg Air Force Base in California on November 18, 2017. After it completes a three-month period of polar orbiting and the advanced instruments are confirmed to be fully functional, the satellite will be ready for weather prediction.

JPSS-1, which will share an orbit with the joint National Oceanic and Atmospheric Administration (NOAA)/NASA Suomi National Polar-orbiting Partnership satellite, has the potential to increase reporting accuracy of upcoming atmospheric events. Its instruments will be able to observe and collect weather pattern data, such as sea-ice cover, fire detection, volcanic ash, and atmospheric temperature. The satellite is also designed to capture post-storm imagery, including storm damage extent and power loss, which could prove beneficial for storm damage recovery efforts."
http://www.astronomy.com/news/2017/1...-is-on-its-way

Its still overcast here, so still can't check anything. You won't see Saturn's rings, just a star in the sky that does not blink, a point of light.

I've just been reading about pulsars: http://earthsky.org/space/2017-marks...ere-discovered. Weird!

Here is something else http://earthsky.org/space/small-mage...tomic-hydrogen

I have to admit I don't really understand this one.

Astronomers at Australian National University (ANU) said on November 28, 2017 that they’ve created the most detailed radio image yet of the Small Magellanic Cloud, a famous sky-sight from Earth’s Southern Hemisphere and a dwarf galaxy orbiting our home galaxy, the Milky Way. The image shows the galaxy not in terms of its stars and dust, as optical images do, but in terms of its hydrogen gas. ANU astronomer Naomi McClure-Griffiths, who co-led the study, said:

Hydrogen is the fundamental building block of all galaxies and shows off the more extended structure of a galaxy than its stars and dust.

She said the image reveals distortions to the Small Magellanic Cloud, which likely occurred because of its interactions with the larger galaxies and because of its own star explosions that push gas out of the galaxy:

The outlook for this dwarf galaxy is not good, as it’s likely to eventually be gobbled up by our Milky Way.

Together, the [Large and Small] Magellanic Clouds are characterised by their distorted structures, a bridge of material that connects them, and an enormous stream of hydrogen gas that trails behind their orbit – a bit like a comet.

Well, I guess this was not so bad as an explanation.

Quote:

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Originally Posted by Dreamwoven

Here is something else http://earthsky.org/space/small-mage...tomic-hydrogen

I have to admit I don't really understand this one.

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Indeed!
Did you notice there is quite a vocabulary of recent astronomy:
exoplanet
Kuiper belt
Red dwarf
White dwarf
Magellanic Cloud
Pulsar
Oort Cloud
Hot Jupiter
etc.

Quote:

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Originally Posted by Dreamwoven

Well, I guess this was not so bad as an explanation.

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It´s ok. A lot of new informations.

Yes, it fine. There are other as well, like Oort Cloud, and Hot Jupiters.

I have included them. We are getting quite a list.

http://earthsky.org/todays-image/can...es-a-full-moon

Enhanced by moonlight, apparently! Nice images...

https://www.universetoday.com/137981...d-galaxy-life/

I wonder what people think of this? I think the idea needs considering much more carefully. As for seeding life in the entire galaxy, I am not happy with it, as it would risk creating a uniformity rather than diversity.

"But perhaps the most daring proposal comes in the form of Project Genesis, which would attempt to seed distant planets with life.

This proposal was put forth by Dr. Claudius Gros, a theoretical physicist from the Institute for Theoretical Physics at Goethe University Frankfurt. In 2016, he published a paper that described how robotic missions equipped with gene factories (or cryogenic pods) could be used to distribute microbial life to “transiently habitable exoplanets – i.e. planets capable of supporting life, but not likely to give rise to it on their own."
https://www.universetoday.com/137981...d-galaxy-life/

Ai, ai,ai!I shudder when I think of the cosmic health of other galaxies!

Yes, Project Genesis is its name. I hope it comes to nought.

http://www.astronomy.com/news/2017/12/voyager-1

Voyager 1 fires dormant thrusters for the first time in 37 years. They made them tough and durable back then!

It is currently over 13 billion miles from Earth and travelling at 40,000 miles an hour. Read the article, it impressive!

Yes, they have to adapt themselves to the old codes!

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3

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. We accept subscription
payments online at our secure site and can take credit and debit
cards. You can join or renew via a secure server or just see how
much we have to offer by visiting http://www.popastro.com/

FIRST INTERSTELLAR ASTEROID IS NOTHING LIKE SEEN BEFORE
ESO

On 2017 October 19 the Pan-STARRS 1 telescope in Hawaii observed a
faint point of light moving across the sky. It looked initially like a
typical fast-moving small asteroid, but additional observations over
the next couple of days allowed its orbit to be computed fairly
accurately. The orbit calculations revealed beyond any doubt that
that body did not originate from inside the Solar System, like all
other asteroids or comets ever observed, but instead had come from
interstellar space. Although it was originally classified as a comet,
observations from ESO and elsewhere revealed no signs of cometary
activity after it passed closest to the Sun in 2017 September. The
object was re-classified as an interstellar asteroid and named
1I/2017 U1 (`Oumuamua). ESO's Very Large Telescope was immediately
called into action to measure the object's orbit, brightness and colour
more accurately than smaller telescopes could achieve. Speed was vital
as `Oumuamua was rapidly fading as it headed away from the Sun and past
the Earth's orbit, on its way out of the Solar System. There were more
surprises to come. Combining the images from the FORS instrument on the
VLT through four different filters with those of other large telescopes,
the team of astronomers found that `Oumuamua varies dramatically in
brightness by a factor of ten as it spins on its axis every 7.3 hours.
That unusually large variation in brightness means that the object is
highly elongated, about ten times as long as it is wide, with a complex,
convoluted shape. They also found that it has a dark red colour,
similar to objects in the outer Solar System, and confirmed that it
is completely inert, without the faintest hint of dust around it.

Those properties suggest that `Oumuamua is dense, possibly rocky or with
high metal content, lacks significant amounts of water or ice, and that
its surface is now dark and reddened owing to the effects of irradiation
from cosmic rays over millions of years. It is estimated to be at least
400 metres long. Preliminary orbital calculations suggested that the
object has come from the approximate present direction of Vega. However,
it has taken it so long for it to make the journey to the Solar System,
even though it has been travelling at a speed of about 26 km/s (95,000
km/h), that Vega was not near that position when the asteroid was there
about 300,000 years ago. `Oumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the Solar System. Astronomers estimate that interstellar asteroids similar to `Oumuamua pass through the inner Solar System about once a year, but they are faint and hard to spot and so have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, were made powerful enough to have a chance of discovering them. Astronomers are continuing to observe this unique object and hope to pin down more accurately where it came from and where it is going next on its tour of the Galaxy.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3


EXOPLANET 55 CANCRI e LIKELY TO HAVE ATMOSPHERE
NASA/JPL

Twice as big as the Earth, the super-Earth 55 Cancri e was thought to
have lava flows on its surface. The planet is very close to its star,
and the same side of the planet always faces the star, so the planet has
permanent day and night sides. On the basis of a 2016 study using data
from the Spitzer Space Telescope, scientists speculated that lava would
flow freely in lakes on the starlit side and become hardened on the face
in perpetual darkness. The lava on the day side would reflect radiation
from the star, contributing to the overall observed temperature of the
planet. Now, a deeper analysis of the same Spitzer data finds that the
planet probably has an atmosphere whose ingredients could be similar to
those of the Earth's atmosphere, but thicker. Scientists have said that
lava lakes directly exposed to space without an atmosphere would create
local hot spots of high temperatures, so they are not the best expla-
nation for the Spitzer observations. Using an improved model of how
energy would flow throughout the planet and radiate back into space,
researchers find that the night side of the planet is not as cool as
previously thought. Even the 'cool' side is still quite toasty by
Earthly standards, at an average of 1,300 to 1,400 Celsius, and the
hot side averages 2,300 Celsius. The difference between the hot and
cold sides would be more extreme if there were no atmosphere.

Researchers say that the atmosphere of the extraordinary planet could
contain nitrogen, water and even oxygen -- molecules found in *our*
atmosphere, too -- but with much higher temperatures throughout. The
density of the planet is also similar to that of the Earth, suggesting
that it, too, is rocky. The intense heat from the host star would be
far too great to support life, however, and could not allow liquid
water. Spitzer observed 55 Cancri e between 2013 June 15 and July 15,
using a camera specially designed for viewing infrared light, which is
an indicator of heat energy. By comparing changes in brightness
observed by Spitzer to energy-flow models, researchers realized that an
atmosphere with volatile materials could best explain the temperatures.
There are many open questions about 55 Cancri e, especially why the
atmosphere has not been stripped away from the planet, given the
perilous radiation environment of the star. Understanding that planet
could help us address larger questions about the evolution of rocky
planets.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3

SPACE DUST MAY TRANSPORT LIFE BETWEEN WORLDS
University of Edinburgh

Fast-moving flows of interplanetary dust that continually bombard our
planet's atmosphere could deliver tiny organisms from far-off worlds, or
send Earth-based organisms to other planets, according to new research.
The dust streams could collide with biological particles in the Earth's
atmosphere with enough energy to knock them into space. Such an event
could enable bacteria and other forms of life to make their way from one
planet in the Solar System to another and perhaps beyond. The finding
suggests that large asteroid impacts may not be the sole mechanism by
which life could transfer between planets, as was previously thought.
The research calculated how powerful flows of space dust -- which can
move at up to 70 km/s -- could collide with particles in our atmospheric
system. It found that small particles existing at 150 km or higher
above the Earth's surface could be knocked beyond retrieval by the
Earth's gravity by space dust and eventually reach other planets. The
same mechanism could enable the exchange of atmospheric particles
between distant planets. Some bacteria, plants and small animals called
tardigrades are known to be able to survive in space, so it is possible
that such organisms -- if present in the Earth's upper atmosphere --
might collide with fast-moving space dust and withstand a journey to
another planet. The proposition that space-dust collisions could propel
organisms over enormous distances between planets raises some exciting
prospects of how life and the atmospheres of planets originated. The
streaming of fast space dust is found throughout planetary systems and
could be a common factor in proliferating life.

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3

DO DARK MATTER AND DARK ENERGY REALLY EXIST?
Universite de Geneve

For close on a century, researchers have hypothesized that the Universe
contains matter that can not be directly observed, known as 'dark
matter'. They have also posited the existence of a 'dark energy' that
is more powerful than gravitational attraction. Those two hypotheses,
it has been argued, account for the movement of stars in galaxies and
for the accelerating expansion of the Universe respectively. But --
according to a researcher at the University of Geneva -- those concepts
may not be valid: the phenomena that they are supposed to describe can
be demonstrated without them. The research exploits a new theoretical
model based on the scale invariance of the empty space, potentially
solving two of astronomy's greatest problems. In 1933, the Swiss
astronomer Fritz Zwicky claimed that there was substantially more matter
in the Universe than we can actually see. Astronomers called that
unknown matter 'dark matter', a concept that was to take on yet more
importance in the 1970s, when the US astronomer Vera Rubin called on
it to explain the movements and speed of the stars. Scientists have
subsequently devoted considerable resources to identifying dark matter
-- in space, on the ground and even at CERN -- but without success. In
1998 a second problem arose: a team of Australian and US astrophysicists
discovered the acceleration of the expansion of the Universe, earning
them after some delay the Nobel Prize for physics in 2011. However, in
spite of much effort, no theory or observation has been able to define
the black energy that is allegedly stronger than Newton's gravitational
attraction. In short, dark matter and dark energy are two problems that
have stumped astronomersfor over 80 years and 20 years respectively.
The way we represent the Universe and its history are described by
Einstein's equations of general relativity, Newton's universal gravita-
tion and quantum mechanics. The model-consensus at present is that of a
big bang followed by an expansion. In that model, there is a starting
hypothesis that seems not to have been taken into account. That is the
scale invariance of the empty space; in other words, the empty space and
its properties do not change following a dilation or contraction. The
empty space plays a primordial role in Einstein's equations as it
operates in a quantity known as the 'cosmological constant', and the
resulting Universe model depends on it. On the basis of that hypothesis,
researchers are now re-examining the model of the Universe, pointing out
that the scale invariance of the empty space is also present in the
fundamental theory of electromagnetism.

When the researchers carried out cosmological tests on the new model,
they found that it matched the observations. They also found that the
model predicts the accelerated expansion of the Universe without having
to factor in any particle or dark energy. In short, it appears that
dark energy may not actually exist, since the acceleration of the
expansion is contained in the equations of the physics. In a second
stage, astronomers focussed on Newton's law, a special case of the
equations of general relativity. The law is also slightly modified when
the model incorporates the new hypothesis. Indeed, it contains a very
small outward acceleration term, which is particularly significant at
low densities. The amended law, when applied to clusters of galaxies,
leads to masses of clusters in line with that of visible matter
(contrary to what Zwicky argued in 1933): that means that no dark matter
is needed to explain the high speeds of the galaxies in the clusters.
A second test demonstrated that the law also predicts the high speeds
reached by the stars in the outer regions of galaxies (as Rubin had
observed), without having to turn to dark matter to describe them.
Finally, a third test looked at the dispersion of the speeds of the
stars oscillating around the plane of the Milky Way. That dispersion,
which increases with the age of the relevant stars, can be explained
very well by the invariant empty space hypothesis, while there was
previously no agreement on the origin of that effect.

https://astronomynow.com/2017/11/10/...und-supernova/

Quote:

---

Originally Posted by Dreamwoven

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3

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. We accept subscription
payments online at our secure site and can take credit and debit
cards. You can join or renew via a secure server or just see how
much we have to offer by visiting http://www.popastro.com/

FIRST INTERSTELLAR ASTEROID IS NOTHING LIKE SEEN BEFORE
ESO

On 2017 October 19 the Pan-STARRS 1 telescope in Hawaii observed a
faint point of light moving across the sky. It looked initially like a
typical fast-moving small asteroid, but additional observations over
the next couple of days allowed its orbit to be computed fairly
accurately. The orbit calculations revealed beyond any doubt that
that body did not originate from inside the Solar System, like all
other asteroids or comets ever observed, but instead had come from
interstellar space. Although it was originally classified as a comet,
observations from ESO and elsewhere revealed no signs of cometary
activity after it passed closest to the Sun in 2017 September. The
object was re-classified as an interstellar asteroid and named
1I/2017 U1 (`Oumuamua). ESO's Very Large Telescope was immediately
called into action to measure the object's orbit, brightness and colour
more accurately than smaller telescopes could achieve. Speed was vital
as `Oumuamua was rapidly fading as it headed away from the Sun and past
the Earth's orbit, on its way out of the Solar System. There were more
surprises to come. Combining the images from the FORS instrument on the
VLT through four different filters with those of other large telescopes,
the team of astronomers found that `Oumuamua varies dramatically in
brightness by a factor of ten as it spins on its axis every 7.3 hours.
That unusually large variation in brightness means that the object is
highly elongated, about ten times as long as it is wide, with a complex,
convoluted shape. They also found that it has a dark red colour,
similar to objects in the outer Solar System, and confirmed that it
is completely inert, without the faintest hint of dust around it.

Those properties suggest that `Oumuamua is dense, possibly rocky or with
high metal content, lacks significant amounts of water or ice, and that
its surface is now dark and reddened owing to the effects of irradiation
from cosmic rays over millions of years. It is estimated to be at least
400 metres long. Preliminary orbital calculations suggested that the
object has come from the approximate present direction of Vega. However,
it has taken it so long for it to make the journey to the Solar System,
even though it has been travelling at a speed of about 26 km/s (95,000
km/h), that Vega was not near that position when the asteroid was there
about 300,000 years ago. `Oumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the Solar System. Astronomers estimate that interstellar asteroids similar to `Oumuamua pass through the inner Solar System about once a year, but they are faint and hard to spot and so have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, were made powerful enough to have a chance of discovering them. Astronomers are continuing to observe this unique object and hope to pin down more accurately where it came from and where it is going next on its tour of the Galaxy.

---

Going by bits:
I think most questions about Oumuamua and similar heavenly objects have still to be answered.

Quote:

---

Originally Posted by Dreamwoven

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3


EXOPLANET 55 CANCRI e LIKELY TO HAVE ATMOSPHERE
NASA/JPL

Twice as big as the Earth, the super-Earth 55 Cancri e was thought to
have lava flows on its surface. The planet is very close to its star,
and the same side of the planet always faces the star, so the planet has
permanent day and night sides. On the basis of a 2016 study using data
from the Spitzer Space Telescope, scientists speculated that lava would
flow freely in lakes on the starlit side and become hardened on the face
in perpetual darkness. The lava on the day side would reflect radiation
from the star, contributing to the overall observed temperature of the
planet. Now, a deeper analysis of the same Spitzer data finds that the
planet probably has an atmosphere whose ingredients could be similar to
those of the Earth's atmosphere, but thicker. Scientists have said that
lava lakes directly exposed to space without an atmosphere would create
local hot spots of high temperatures, so they are not the best expla-
nation for the Spitzer observations. Using an improved model of how
energy would flow throughout the planet and radiate back into space,
researchers find that the night side of the planet is not as cool as
previously thought. Even the 'cool' side is still quite toasty by
Earthly standards, at an average of 1,300 to 1,400 Celsius, and the
hot side averages 2,300 Celsius. The difference between the hot and
cold sides would be more extreme if there were no atmosphere.

Researchers say that the atmosphere of the extraordinary planet could
contain nitrogen, water and even oxygen -- molecules found in *our*
atmosphere, too -- but with much higher temperatures throughout. The
density of the planet is also similar to that of the Earth, suggesting
that it, too, is rocky. The intense heat from the host star would be
far too great to support life, however, and could not allow liquid
water. Spitzer observed 55 Cancri e between 2013 June 15 and July 15,
using a camera specially designed for viewing infrared light, which is
an indicator of heat energy. By comparing changes in brightness
observed by Spitzer to energy-flow models, researchers realized that an
atmosphere with volatile materials could best explain the temperatures.
There are many open questions about 55 Cancri e, especially why the
atmosphere has not been stripped away from the planet, given the
perilous radiation environment of the star. Understanding that planet
could help us address larger questions about the evolution of rocky
planets.

---

Determine the atmosphere of 55 Cancri would indeed represent a considerable advancement.

Quote:

---

Originally Posted by Dreamwoven

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3

SPACE DUST MAY TRANSPORT LIFE BETWEEN WORLDS
University of Edinburgh

Fast-moving flows of interplanetary dust that continually bombard our
planet's atmosphere could deliver tiny organisms from far-off worlds, or
send Earth-based organisms to other planets, according to new research.
The dust streams could collide with biological particles in the Earth's
atmosphere with enough energy to knock them into space. Such an event
could enable bacteria and other forms of life to make their way from one
planet in the Solar System to another and perhaps beyond. The finding
suggests that large asteroid impacts may not be the sole mechanism by
which life could transfer between planets, as was previously thought.
The research calculated how powerful flows of space dust -- which can
move at up to 70 km/s -- could collide with particles in our atmospheric
system. It found that small particles existing at 150 km or higher
above the Earth's surface could be knocked beyond retrieval by the
Earth's gravity by space dust and eventually reach other planets. The
same mechanism could enable the exchange of atmospheric particles
between distant planets. Some bacteria, plants and small animals called
tardigrades are known to be able to survive in space, so it is possible
that such organisms -- if present in the Earth's upper atmosphere --
might collide with fast-moving space dust and withstand a journey to
another planet. The proposition that space-dust collisions could propel
organisms over enormous distances between planets raises some exciting
prospects of how life and the atmospheres of planets originated. The
streaming of fast space dust is found throughout planetary systems and
could be a common factor in proliferating life.

---

Yes, that would be the interstellar organic dust theory.

Quote:

---

Originally Posted by Dreamwoven

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 458 2017 December 3

DO DARK MATTER AND DARK ENERGY REALLY EXIST?
Universite de Geneve

For close on a century, researchers have hypothesized that the Universe
contains matter that can not be directly observed, known as 'dark
matter'. They have also posited the existence of a 'dark energy' that
is more powerful than gravitational attraction. Those two hypotheses,
it has been argued, account for the movement of stars in galaxies and
for the accelerating expansion of the Universe respectively. But --
according to a researcher at the University of Geneva -- those concepts
may not be valid: the phenomena that they are supposed to describe can
be demonstrated without them. The research exploits a new theoretical
model based on the scale invariance of the empty space, potentially
solving two of astronomy's greatest problems. In 1933, the Swiss
astronomer Fritz Zwicky claimed that there was substantially more matter
in the Universe than we can actually see. Astronomers called that
unknown matter 'dark matter', a concept that was to take on yet more
importance in the 1970s, when the US astronomer Vera Rubin called on
it to explain the movements and speed of the stars. Scientists have
subsequently devoted considerable resources to identifying dark matter
-- in space, on the ground and even at CERN -- but without success. In
1998 a second problem arose: a team of Australian and US astrophysicists
discovered the acceleration of the expansion of the Universe, earning
them after some delay the Nobel Prize for physics in 2011. However, in
spite of much effort, no theory or observation has been able to define
the black energy that is allegedly stronger than Newton's gravitational
attraction. In short, dark matter and dark energy are two problems that
have stumped astronomersfor over 80 years and 20 years respectively.
The way we represent the Universe and its history are described by
Einstein's equations of general relativity, Newton's universal gravita-
tion and quantum mechanics. The model-consensus at present is that of a
big bang followed by an expansion. In that model, there is a starting
hypothesis that seems not to have been taken into account. That is the
scale invariance of the empty space; in other words, the empty space and
its properties do not change following a dilation or contraction. The
empty space plays a primordial role in Einstein's equations as it
operates in a quantity known as the 'cosmological constant', and the
resulting Universe model depends on it. On the basis of that hypothesis,
researchers are now re-examining the model of the Universe, pointing out
that the scale invariance of the empty space is also present in the
fundamental theory of electromagnetism.

When the researchers carried out cosmological tests on the new model,
they found that it matched the observations. They also found that the
model predicts the accelerated expansion of the Universe without having
to factor in any particle or dark energy. In short, it appears that
dark energy may not actually exist, since the acceleration of the
expansion is contained in the equations of the physics. In a second
stage, astronomers focussed on Newton's law, a special case of the
equations of general relativity. The law is also slightly modified when
the model incorporates the new hypothesis. Indeed, it contains a very
small outward acceleration term, which is particularly significant at
low densities. The amended law, when applied to clusters of galaxies,
leads to masses of clusters in line with that of visible matter
(contrary to what Zwicky argued in 1933): that means that no dark matter
is needed to explain the high speeds of the galaxies in the clusters.
A second test demonstrated that the law also predicts the high speeds
reached by the stars in the outer regions of galaxies (as Rubin had
observed), without having to turn to dark matter to describe them.
Finally, a third test looked at the dispersion of the speeds of the
stars oscillating around the plane of the Milky Way. That dispersion,
which increases with the age of the relevant stars, can be explained
very well by the invariant empty space hypothesis, while there was
previously no agreement on the origin of that effect.

---

And one thing modern research demonstrates with the modernization of sky telescopes and other instruments, is that the sky contains much more heavenly bodies and debris than we thought before.

Quote:

---

Originally Posted by Dreamwoven

https://astronomynow.com/2017/11/10/...und-supernova/

---

Impressive to look at. Am also impressed how far reaching the modern instruments are.

reply to #1468

This intergalactic visitor has only been seen once, hopefully it will return each year, allowing more info to be gathered.

Oumuamua looks more like an interstellar joke than anything else. Do you remember the UFOs?

Its well described in this post, especially how the co-operation between the various observation points is done to build up an image. And now that it has been studied, and its trajectory plotted, it will be interesting to watch for when it returns.

Hubble has done sterling work, and the supernova it spotted was an extra bonus.

https://www.universetoday.com/137996...1600-galaxies/

This is another first for Hubble, looking back at the past.

https://www.universetoday.com/137995...lanets-galaxy/

This is not about anything new, just a reaffirmation of what we know already.

Quote:

---

Originally Posted by Dreamwoven

https://www.universetoday.com/137996...1600-galaxies/

This is another first for Hubble, looking back at the past.

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"Looking to this region of space, multiple teams of astronomers used the MUSE instrument on the ESO’s Very Large Telescope (VLT) to discover 72 previously unseen galaxies. In a series of ten recently released studies, these teams indicate how they measured the distance and properties of 1600 very faint galaxies in the Ultra Deep Field, revealing new information about star formation and the motions of galaxies in the early Universe.

The original HUDF images, which were published in 2004, were a major milestone for astronomy and cosmology. The thousands of galaxies it observed were dated to less than just a billion years after the Big Bang, ranging from 400 to 800 million years of age. This area was subsequently observed many times using the Hubble and other telescopes, which has resulted in the deepest views of the Universe to date."
To the astronomers this must be a feast!

Quote:

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Originally Posted by Dreamwoven

https://www.universetoday.com/137995...lanets-galaxy/

This is not about anything new, just a reaffirmation of what we know already.

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"In the hunt for extra-terrestrial life, scientists tend to take what is known as the “low-hanging fruit approach”. This consists of looking for conditions similar to what we experience here on Earth, which include at oxygen, organic molecules, and plenty of liquid water. Interestingly enough, some of the places where these ingredients are present in abundance include the interiors of icy moons like Europa, Ganymede, Enceladus and Titan.

Whereas there is only one terrestrial planet in our Solar System that is capable of supporting life (Earth), there are multiple “Ocean Worlds” like these moons. Taking this a step further, a team of researchers from the Harvard Smithsonian Center for Astrophysics (CfA) conducted a study that showed how potentially-habitable icy moons with interior oceans are far more likely than terrestrial planets in the Universe."

I like the name the give to this kind of research: the “low-hanging fruit approach”.