A place to hang out and chat about astronomy
Sun Feb 14, 2016 11:25 pm
The Sky at Night TV programme about the theoretical discovery of "Planet 9" this evening was surprisingly informative. All computer models to explain the aligned orbits of some Kuiper belt objects.
Mon Feb 15, 2016 11:04 pm
Interesting stuff... They make a good argument. Though the last statement [That Planet Nine's discovery will be the astronomical discovery of the century] was probably made before last week's announcement of the discovery of Gravity waves.
Enjoyed the programme.
Thu Feb 18, 2016 12:16 am
Yes, but gravity waves were predicted by Einstein. It's taken 90 years to develop and build the technology to detect gravity waves. The Planet 9 prediction is a new one. The snag is that is at its closet approach it is 200AU and its orbit is 10,000yrs, and it has a size estimate of twice to 4 times that of Earth. So a very small dot to find in the sky. But it's a problem being worked on.
Thu Feb 18, 2016 3:05 pm
If Einstein had come up with his prediction today we would have the technology to check his theory - All we'd have to do would be wait for a suitable event. So, really, it only took 90 years because we didn't have the technology - It wouldn't take 90 years to develop the technology now.
Re: The SaN Planet 9 programme:
I did notice that the objects they've found are all in the innermost part of their orbits. How many are there that they haven't discovered? How many of those spoil the 105 degree spread of the ones so far found? If they are all tilted at 7 degrees and they are spread all around the Sun, that would be a very weird finding!
A very interesting programme that posed more questions than it answered!
Sun Feb 28, 2016 6:31 pm
Its taken me a while to get this downloaded so I've only just been able to watch it. (Downloading video in rural Lincolnshire is painful business!)
There are a couple of things that struck me. Firstly if the number of eccentric orbits of planets so far observed is so great, then perhaps a stable 'inner' solar system is less likely than we thought. I also notice that it relies on a 'passing star' theory to get the really eccentric orbit, rather than the interaction with the 'inner' solar system. (We've had 'passing star' theories before, and they tend to be used when theories are lacking) I also noticed that it wasn't only 'planet 9' which was perturbed by the interaction. If you look carefully at the model, another one of the planets was kicked out of the usual plane of the solar system. (Saturn I think).
So the existance of such a planet is not so far fetched as to be dismissed, but it seems the evidence for it happening here is a bit too 'if, if, if' for me. The trouble with so many 'ifs' is that it starts to sound like the chatter of 'infinite monkeys'.
Mon Feb 29, 2016 12:07 am
I note from the March 2016 S@N mag that Chris Lintott takes the view that we should search the Kuiper Belt to improve our knowledge of the range of orbits to see if the majority are aligned with solar system as we know it - hence falsifying the Planet 9 theory - out if there are a enough eccentric orbits to fit the theory of Planet 9.
Mon Apr 18, 2016 10:02 pm
It doesn't rule out the possibility of a Planet 10 as well.
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