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Why are the rocks in the centre "fused together"? Gravity. What other force is there that makes the Moon spherical and holds it together? The point you make ab
by CanSpice 12y ago
Why are the rocks in the centre "fused together"? Gravity. What other force is there that makes the Moon spherical and holds it together?
The point you make about the tidally-locked orbit doesn't hold. Tidal forces are there whether or not the object is tidally locked. The tidal forces would be high enough to rip the Moon apart if it's as close to the Earth as in this article.
The Roche limit can be derived for rigid bodies (like the Moon) or liquid bodies. The one for rigid bodies is closer to the central body than the one for liquid bodies.
- ars 12y ago> Why are the rocks in the centre "fused together"? Gravity. That's what fused them in the first place but they hold together on their own now. Like an asteroid - it's a big rock, gravity is not the force holding it together. Unlike the earth which has a liquid core, as far as I know the moon is a single solid chunk of rock. So the Roche limit is not an accurate measure - you need to take into account the tensile strength of rock. > The point you make about the tidally-locked orbit doesn't hold. Tidal forces are there whether or not the object is tidally locked. You misunderstood me. In a rotating body the tide would cause the object to flex on every rotation, given enough time it would surely break apart from material fatigue. But in a tidally locked body the force is applied once (a stretching force) and stays that way, so there is no fatigue - either it's strong enough or it's not.
- cma 12y agoI thought when the rocks collided (albeit due to gravity at some level), some fused together from the kinetic energy turning to heat.