Quote:
Originally posted by Tipsy
We talking here about perm. moons or perm. and temp. moons?
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I think the definition of a moon is that it is permanent. Well, at least for 100,000,000 years. I think there's a moon around Jupiter in a retrogade motion which is against the tidal forces of the parent planet, so it is being pulled into the planet (the orbit is getting smaller). Eventually, it will reach the roche limit, and break apart from tidal forces, and form another ring. So, it's not
really permanent, but you know... 100,000,000 years is good enough to be considered permanent.
I hope this clears things up.
Roche limit (rsh)
n.
The smallest distance at which a natural satellite can orbit a celestial body without being torn apart by the larger body's gravitational force. The distance depends on the densities of the two bodies and the orbit of the satellite.