Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: geoffthrob on 10/03/2009 20:16:41
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The earth orbits the sun due to the gravitational pull of the sun. The suns gravitational pull must be imense so why is planet earth simply not pulled into the sun? Thanks for your help. [;D]
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The earth is continuously falling toward the sun; however it is moving horizontal to the sun so it misses the sun as it falls. This keeps the earth in a stable orbit about 93 million miles away from the sun.
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The Earth needs a force tugging it to keep it moving in a circle ~(well, an ellipse, actually) That force is provided by the attraction to the Sun. If it were more, then it would be closer in and if it were less it would be further out but it would still balance out.
The other question, of course, is why the planets tend to have orbits which are, in fact, almost circular.
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Correct me if I am wrong; but I suspect that the almost circular orbits evolve from the accretion disk. Objects that interact with each other in the disk would exist in a ring about a centre of mass. This would lead to lumpy build-ups with circular orbits.