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View Full Version : Excellent read on the state of confusion regarding solar system formation.



rwatts
07-03-2014, 02:16 PM
Astronomy: Planets in chaos (http://www.nature.com/news/astronomy-planets-in-chaos-1.15480)

It begins thus:-


Not so long ago — as recently as the mid-1990s, in fact — there was a theory so beautiful that astronomers thought it simply had to be true.

They gave it a rather pedestrian name: the core-accretion theory. But its beauty lay in how it used just a few basic principles of physics and chemistry to account for every major feature of our Solar System. It explained why all the planets orbit the Sun in the same direction; why their orbits are almost perfectly circular and lie in or near the plane of the star's equator; why the four inner planets (Mercury, Venus, Earth and Mars) are comparatively small, dense bodies made mostly of rock and iron; and why the four outer planets (Jupiter, Saturn, Uranus and Neptune) are enormous, gaseous globes made mostly of hydrogen and helium. And because the same principles of physics and astronomy must apply throughout the Universe, it predicted that any system of 'exoplanets' around another star would look pretty much the same.

But in the mid-1990s, ...

Roy
07-03-2014, 02:41 PM
997

Roy

Jedidiah
07-03-2014, 05:12 PM
And we thought we had a good handle on that. Rats!

klaus54
07-03-2014, 06:47 PM
"Man's fallible word, God's INFALLIBLE Word?"

Simple.

K54

lilpixieofterror
07-03-2014, 08:05 PM
I think another interesting question to ask is why our solar system looks so much different than these other ones do.

rwatts
07-03-2014, 11:54 PM
And we thought we had a good handle on that. Rats!I know.

To an extent though, parts of the old theory will remain - gravitational accretion, accretion disks etc. It's not as if nothing has been learned.

rwatts
07-03-2014, 11:56 PM
I think another interesting question to ask is why our solar system looks so much different than these other ones do.Yes.

However, I don't think they really know just how rare our kind of solar system is yet. I don't think they quite have the technology to address this question.

Roy
07-04-2014, 01:43 PM
Yes.

However, I don't think they really know just how rare our kind of solar system is yet. I don't think they quite have the technology to address this question.One problem is that the types of planet we can most easily find are those that differ from the ones we are familiar with.

Roy

oxmixmudd
07-04-2014, 04:34 PM
One problem is that the types of planet we can most easily find are those that differ from the ones we are familiar with.

Roy

Yep. That confuses me a bit. Almost every method we have, including Kepler, favors relatively large and/or close objects with shorter orbital periods. So, while it is very clear the dynamics of planetary formation are a good bit more complex than the model discussed, we really don't know enough to define true percentages as is implied.

Jim