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About planetray rotation
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by taku_RazorLemon
on 2006-04-20 07:19:58
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I was just wondering: why does the Earth rotate vertically instead of horizontally? And why do planets rotate, for that matter?   |
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Re: About planetray rotation
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by
on 2006-04-20 09:53:51 |
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all things rotate because they have angular momentum. all things with angular momentum were acted upon by some force. the formation of the planets resulted in net angular momentum left over, in our case it causes the earth to revolve once every day. 
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Re: About planetray rotation
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Life kind of isn't balanced though. But if we look back to our solar system being formed, one would see all the planets slowly being formed by accretion. But there was still quite a bit of material left, even with other planet-sized spheres formed besides the 9 in the present. So, gravity acted and spheres collided into each other. Thus, gendou's right in a way, as it was not the formation in a sense, but the residual objects slamming into each other with force enough to impart a spin. That's how Uranus spins on its side relative to its orbit, as it was forced that way by an event, not by natural formation. Earth's spin is tilted at 66.5 degrees because a large object slammed into Earth at an angle to impart that spin, giving us the moon as a parting gift. Because it was a glancing blow, our axis isn't tilted terribly. |
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Re: About planetray rotation
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| Actually the earth and uranus could have formed with their current angular momentum. you must remember that even if the solar sistem had a larger tangetial velocity and a big acumulation of mass in the center causing a spiral effect, there where areas within the whole nebula wich created alternative mass concentrations(protoplanets) and probably each one had its own matter moving in an spiral way arround it; while still following the bigger spiral path produced by the sun(small spirals spiraling arround the sun). The problem is that you are probably imagining it as 2d model, try to expand it to 3d and you'll notice that you could even have a second earth in a 90° angle in its traslation movement and it wouldnt matter. The solar system is so flat, posibly because it was created by matter with high tangential velocity which made it a spiral, but had the velocity had been less it would probably had been an egg shaped system. |