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elizabeth25
2012-Feb-20, 04:19 PM
Just been reading the Universe today site, it shows this image

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personally i think its a beautiful image, but my question is, What kind of effect would it have on our planet if another planet was that close to us?

antoniseb
2012-Feb-20, 05:38 PM
... What kind of effect would it have on our planet if another planet was that close to us?

I don't know how close that planet is, since we don't really get a sense of what angle it is taking up in the sky... but a few examples... first look at Enceladus and Io. Both are shooting stuff out into space as a result of tidal heating. Slightly further out, look at Titan and Ganymede. Both of these are relatively stable geologically. IF the Earth were very close to a giant planet, but outside the Roche limit, and in a very nearly circular orbit, it would be tidally locked to always face the same side to the giant planet, but otherwise things might be fine.

elizabeth25
2012-Feb-20, 08:57 PM
Thanks antoniseb,

I have another question but not sure how to put it into words, sorry if it comes out confusing, here goes...

Is it possible for two planets to orbit around a sun on the same orbit?

for example, this image shows the order of the planets in our solar system, where Earth is, would another planet be able to orbit on the same white ring?

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Jeff Root
2012-Feb-20, 11:30 PM
Yes, computer simulations have shown that it should be quite
easy for two planets to form in the same orbit around a star, or
two moons to form in the same orbit around a planet. However,
they don't tend to last for very long. Eventually they interact
and either collide or get thrown into different orbits.

-- Jeff, in Minneapolis

antoniseb
2012-Feb-21, 12:54 AM
... Eventually they interact and either collide or get thrown into different orbits....
Yes. Just as an example, you've probably seen/read/heard about the Mars-sized planet that smashed into Early Earth, causing the Moon to be formed from the debris? That Mars-sized planet is thought by some to have formed in the same orbit as Earth, but one sixth of a year ahead or behind us.

elizabeth25
2012-Feb-21, 01:41 PM
Yes. Just as an example, you've probably seen/read/heard about the Mars-sized planet that smashed into Early Earth, causing the Moon to be formed from the debris? That Mars-sized planet is thought by some to have formed in the same orbit as Earth, but one sixth of a year ahead or behind us.

Yeah i have read about that, would that happen even if the two planets were on opposite sides of the sun? would they still eventually collide?

antoniseb
2012-Feb-21, 01:50 PM
Yeah i have read about that, would that happen even if the two planets were on opposite sides of the sun? would they still eventually collide?
Being on opposite sides is a less stable situation than is one-sixth of the way. The least little perturbations from Jupiter, or anything else would move it into an orbit that would eventually be quite different than ours... again, perhaps hitting us.