Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Anastasia.fr.1 on 02/08/2007 10:55:27

Title: how does our moon know ?
Post by: Anastasia.fr.1 on 02/08/2007 10:55:27
how does our moon know just to orbit earth not other planits such as :mars and venus there close to us  [?]
Title: how does our moon know ?
Post by: lightarrow on 02/08/2007 13:17:51
Quote from: Anastasia.fr.1 on 02/08/2007 10:55:27
how does our moon know just to orbit earth not other planits such as :mars and venus there close to us  [?]
Because Earth is much closer to the Moon than Mars or Venus.
Title: how does our moon know ?
Post by: daveshorts on 02/08/2007 13:46:19
The moon doesn't 'know' to orbit the earth it is just falling all the time. All the planets are pulling on the moon a bit but the earth is much closer than the rest of the planets (about a hundreth of the closest that Venus ever comes) and because the force of gravity reduces with the square of the distance, if venus is 100 times further away it's gravity will be 100x100 = 10000 times weaker.

This means that it is basically falling towards the earth all the time, but because it is moving to start with it always misses

For more about why the moon orbits the earth have a look at:
http://www.chaosscience.org.uk/pub/public_html//article.php?story=20040629175315124
which I wrote a couple of years ago.
Title: how does our moon know ?
Post by: syhprum on 02/08/2007 22:47:11
Quote from: daveshorts on 02/08/2007 13:46:19
This means that it is basically falling towards the earth all the time, but because it is moving to start with it always misses
I am relived to hear that I hope it remembers to keep going