Atheist, You have an interest in astronomy, I see. Can you actually see the moons of saturn? What kind of telescope do you have?
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Atheist, You have an interest in astronomy, I see. Can you actually see the moons of saturn? What kind of telescope do you have?
The SOCIETY for POPULAR ASTRONOMY
Electronic News Bulletin No. 414 2016 January 24
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/
EVIDENCE OF A REAL NINTH PLANET
California Institute of Technology
Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer Solar System. The object, which the researchers have nicknamed Planet Nine, is supposed to have a mass about 10 times that of the Earth and orbits about 20 times further from the Sun on average than Neptune (which does so at an average distance of 2800 million miles). In fact, it would take the (still-hypothetical) planet between 10,000 and 20,000 years to orbit round the Sun. The researchers' evidence for the planet's existence came through mathematical modelling and computer simulations; they have not observed the object directly. There have been only two true planets discovered since ancient times, and this would be a third. The putative ninth planet -- at 5,000 times the mass of Pluto -- is sufficiently large that there should be no debate about whether it is a true planet. Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighbourhood of the Solar System. In fact, it dominates a region larger than any of the known planets.
The road to the theoretical discovery was not straightforward. In 2014, astronomers noted that 13 of the most distant objects in the Kuiper Belt are similar with respect to an obscure orbital feature. To explain that similarity, they suggested the possible presence of a small planet. A year-and-a-half-long collaboration began to investigate the distant objects. Fairly quickly it was realized that the six most distant objects from the original 13 under study all follow elliptical orbits that point in the same direction in space. That is particularly surprising because the outermost points of their orbits move around the Solar System, and they travel at different rates. It is almost like having six hands on a clock all moving at different rates, and when you happen to look up, they're all in exactly the same place. The odds of having that happen are something like 1 in 100. But on top of that, the orbits of the six objects arealso all tilted in the same way -- pointing about 30 degrees downward in the same direction relative to the plane of the eight known planets. The probability of that happening is about 0.007%. It could not happen randomly, so something must be shaping the orbits.
The first possibility investigated by astronomers was that perhaps there are enough distant Kuiper-Belt objects -- some of which have not yet been discovered -- to exert the gravity needed to keep that sub-population clustered together. The researchers quickly ruled that out when it turned out that such a possibility would require the Kuiper Belt to have about 100 times the mass that it actually has. That left them with the idea of a planet. Their first instinct was to run simulations involving a planet in a distant orbit that encircled the orbits of the six Kuiper-Belt objects, acting like a giant lassoo to wrangle them into their alignment. That almost works but does not provide the observed eccentricities precisely. Then, effectively by accident, the team noticed that if they ran their simulations with a massive planet in an anti-aligned orbit -- an orbit in which the planet's closest approach to the Sun, or perihelion, is 180 degrees away from the perihelion of all the other objects and known planets -- the distant Kuiper-Belt objects in the simulation assumed the alignment that is actually observed. Through a mechanism known as mean-motion resonance, the anti-aligned orbit of the ninth planet actually prevents the Kuiper-Belt objects from colliding with it and keeps them aligned. As orbiting objects approach each other they exchange energy. So, for example, for every four orbits Planet Nine makes, a distant Kuiper-Belt object might complete nine orbits. They never collide. Instead, like a parent maintaining the arc of a child's swing by periodic pushes, Planet Nine nudges the orbits of distant Kuiper-Belt objects such that their configuration with relation to the planet is preserved.
Planet Nine's existence helps to explain more than just the alignment of the distant Kuiper-Belt objects. It also provides an explanation for the curious orbits that two of them trace. The first of those objects, dubbed Sedna, was discovered in 2003. Unlike standard-variety Kuiper-Belt objects, which can get gravitationally 'kicked out' by Neptune but can then return back to it, Sedna never gets very close to Neptune. A second object like Sedna, known as 2012 VP113, was announced in 2014. The presence of Planet Nine in its proposed orbit naturally produces Sedna-like objects by taking a standard Kuiper-Belt object and slowly pulling it away into an orbit less connected to Neptune. But the real clincher for the researchers was the fact that their simulations also predicted that there would be objects in the Kuiper Belt on orbits inclined perpendicularly to the plane of the planets. In the last three years, observers have identified four objects tracing orbits roughly along one perpendicular line from Neptune and one object along another. Where did Planet Nine come from and how did it end up in the outer Solar System? Scientists have long believed that the early Solar System began with four planetary cores that went on to grab all of the gas around them, forming the four gas planets -- Jupiter, Saturn, Uranus, and Neptune. Over time, collisions and ejections shaped them and moved them out to their present locations. But there is no reason why there could not have been five cores, rather than four. Planet Nine could represent that fifth core, and if it got too close to Jupiter or Saturn, it could have been ejected into its distant, eccentric orbit. Researchers continue to refine their simulations and learn more about the planet's orbit and its influence on the distant Solar System. Meanwhile, astronomers have begun searching the skies for it. Only a rough orbit is indicated, not the precise location of the planet. If the planet happens to be close to its perihelion, astronomers should be able to find it in images captured by previous surveys. If it is in the most distant part of its orbit, the world's largest telescopes will be needed to see it. If, however, Planet Nine is now located anywhere in between, many telescopes might have a shot at finding it.
I wonder if it would become visible without a telescope at some point in the future?
I'm surprised that many smaller planets would not have the same gravitational effect as one large one.
We do know that Jupiter acts as a magnet for all sorts of stray asteroids, like the one that broke up into smaller bits and that crashed into Jupiter.
This is an interesting explanation of the birth of our moon.
http://www.space.com/31763-moon-crea...ekly_2016-1-29
Very violent, and creating a moon that is unusually-large in terms of the relationship between the earth and the moon, such that tides play an important part in creating earth's seas, and producing a very lively interaction.
http://earthsky.org/space/is-our-mil...laxy-a-zombie?
A "dead" galaxy, that has stopped producing more stars? An interesting thought...
Using the zombie metaphor seems odd. The galaxy is just not as active in producing new stars as others are. But those newer, blue stars don't live as long as the red ones. So maybe being a zombie means a longer life.
It was interesting that they needed help from volunteers to manually classify galaxies at the galaxyzoo site.
galaxy zoo is a new idea to me, not come across it before. I've added it to my astronomy tags. The website talks about the zooniverse...
Thanks, YesNo.
I haven't actually gone to the site since I figured I wouldn't have time to volunteer for any of the activities they might have at the moment, but it is interesting that there is something any of us could do to help these guys. We could become more than consumers of this information.
Pluto has strange floating hills. Read about them here
Whenever US Global hegemony is challenged, as it is now by Russia (Putin), cut-backs in the space programme appear to be threatened. See http://www.space.com/31886-nasa-2017...ekly_2016-2-10
Gravitational waves look likely to be confirmed today.
Its not clear why this would be so revolutionary, Einstein predicted this way back, but EarthSky seem to think it would be.
Another source... 'chirp': http://www.nytimes.com/2016/02/12/sc...tein.html?_r=0
Ta ! (short for tarradiddle),Quote:
A team of scientists announced on Thursday that they had heard and recorded the sound of two black holes colliding a billion light-years away, a fleeting chirp that fulfilled the last prediction of Einstein’s general theory of relativity.
That faint rising tone, physicists say, is the first direct evidence of gravitational waves, the ripples in the fabric of space-time that Einstein predicted a century ago (Listen to it here.) It completes his vision of a universe in which space and time are interwoven and dynamic, able to stretch, shrink and jiggle. And it is a ringing confirmation of the nature of black holes, the bottomless gravitational pits from which not even light can escape, which were the most foreboding (and unwelcome) part of his theory.
More generally, it means that a century of innovation, testing, questioning and plain hard work after Einstein imagined it on paper, scientists have finally tapped into the deepest register of physical reality, where the weirdest and wildest implications of Einstein’s universe become manifest"
tailor STATELY
I'm glad they got LIGO to detect something of interest. Now to overcome my cognitive dissonance over the existence of black holes.
What cognitive dissonance is that, YesNo?
Like all cognitive dissonance, it's confusing to explain.
A few weeks ago, I had no problem with black holes. I didn't think about them. Then I heard they could not exist. That was the first cognitive dissonance I had to confront on the subject. So I thought about it and checked out some internet sources and I figured it makes sense that they do not exist since we didn't see what we expected at the center of our galaxy. So I overcame that cognitive dissonance by changing my mind about black holes.
Now I hear that gravity waves are supposed to imply the existence of something like black holes causing those gravity waves. That is the second cognitive dissonance. It sort of puts me back into my original position, but that isn't very comforting. Now I will have to learn more about black holes. If they are neutron stars, it relieves the dissonance a bit, because they are larger than a point in space about the size of what started the big bang.
I don't have any problem with gravity waves as such because I never thought of them.
I didn't either. Clearly, great minds don't think alike.Quote:
Originally Posted by YesNo
There has still nothing been said about how this changes things. Just knowing about the existence of gravity waves isn't enough. Can we use the knowledge, perhaps by utilising their existence in some way or other. A bit like how sailing can utilise water waves? Which direction do the waves go? From the black hole outwards or into the black hole?
I think of the black hole as a pebble dropped into the ocean, but that would mean it is pushing waves away from it. The black hole would likely be attracting those waves--at least metaphorically.
Also, how did they know where to point their instrument? And doesn't it seem a little too convenient that those black holes merged together just in time for this instrument to detect it? And how did they separate those specific black holes from all the others out there making gravity waves?
There is nothing like cognitive dissonance to generate skepticism.
I think of black holes as being either pushing waves away from it or drawing waves into it. But its all speculation at this point in time. A bit like the warp drive in Star Trek. Some galaxies, like the Milky Way, are quiescent and others are very active, producing many new stars.
The warp drive is interesting. I suspect the speed of light even in a vacuum may have some variance, that is, it is not a mathematical constant. If that is the case light might be able to go faster or slower. North Star pointed out in another thread that Lene Hua found a way to make light stop: https://www.youtube.com/watch?v=-8Nj2uTZc10
If one thinks about light's speed then we are within space and time, otherwise we couldn't measure anything. However, the non-local behavior of entangled particles is not just "faster" than light. It is instantaneous. There is no space or time to restrict it. Or at least, so I suspect at the moment.
Its odd that we are only just learning more about other galaxies than our own. All the fancy telescopes like James Webb Space Telescope. We now see how galaxies collide and produce new stars. It is a whole new world out there.
More news on Black Holes and Gravitation Waves.
That article makes me wonder what is a black hole. If it is a collapsed star so that the light can no longer escape, that seems possible. That is not a "singularity". It is just a kind of star.
It is interesting that the pairs were calculated as having 29 and 36 times the mass of our Sun. That doesn't seem very large. Also they don't know precisely where this occurred, just a certain region of space. I guess what we need is another LIGO to pin point better the location of these objects.
Another thing I wonder about is when we are given a number like 29 times the mass of the Sun what is the margin of error for that calculation? I assume the margin of error is 0.5 because we are given a number precise to the units position, but it could be anything.
Another theory is that instead of a massive planet 9, there is a second Kuiper Belt of many smaller objects: a Kuiper Belt 2.
It is good to have multiple theories. If there is only one, I tend to assume it has been validated before much evidence is available. At least they aren't saying it is dark matter that is modifying the orbits of the Kuiper Belt objects.
This dragon-like salamander has a life of up to 100 years. Live in the caves of Postonja in Slovenia. Recently found the first egg of this species.
EarthSky has a nice article on the potential of moons to influence habitability on the planets moons often circulate around.
It's interesting that the Moon stabilizes the seasons by keeping the Earth't tilt stable. But no known exomoons to date.
Most exmoons, like in our sun (star), will be too far away for us to identify them. How far away is the nearest star? Do we know if any planets orbit it? And even harder, how many moons orbit its planets, how large they are? We still know next to nothing about our galaxy, let alone the stars in the Milky Way Galaxy.
We didn't even know that Pluto had moons until recently.
One of the things that puzzles me the most about astronomy is I don't know the margin of error around what we think is correct.
This post on Phobos is interesting: http://www.space.com/32152-mars-myst...ekly_2016-3-07. Its the closest moon to any planet so far discovered. And it is gradually spiralling into Mars. Strains in Phobos structure are beginning to show, as well.
It is interesting that the moons of Mars were unknown prior to 1877 and in the 1950's it was conjectured that Phobos may be artificial because of its low orbit. This conjecture was later rejected. This comes from a link in the link you cited: http://www.space.com/20346-phobos-moon.html
See this interesting post in NeuroLogica Blog: http://theness.com/neurologicablog/i...moons-of-mars/. Not a bad guess by Jonathan Swift.
It looks like Swift was satirizing scientists. I suspect he got the idea of Mars having two moons from Kepler.
Must have done. en.wikipedia.org/wiki/Moons_of_Mars
Two comets making close flybys of Earth in late March:
http://earthsky.org/space/twin-comet...osely-in-march
I'll see if I can find that comet this evening.
More on Pluto. We are beginning to learn a lot about our own solar system. An exciting time in astronomy: http://www.space.com/32301-pluto-sur...-horizons.html
I didn't expect Pluto to be still active. It is a good reminder that models and reality are not likely the same thing. Look closer and the models start falling apart. Of course one of the reasons to emphasize the new, model-shaking information that New Horizons has provided is to get an extended mission which requires funding. Since New Horizons is already out there, we might as well look.