|
|
 Originally Posted by Poopadoop
So how does Newton explain the moon not crashing into Earth? It's inertia is what is keeping it going?
Why then (from either N or E's perspective) do some orbits decay? The thing is not going fast enough to overcome the pull of gravity I suspect?
Gravity is one form of energy. It's effect on orbits is not the only effect.
Consider the tides are caused by the moon (and the Earth's rotation under the seas, to a degree). There is energy transfer from the Moon's orbital energy into tidal energy. So the energy in the moon's orbit must not be constant.
There are other effects. Tidal heating is when the gravitation is not merely enough to pull water around, but the actual rock the body is made of. Many of Jupiter's moons have volcanic activity due to the constant squeezing and stretching of the moon like a stress ball. It heats the interior of the moon and keeps it molten.
Other effects serve to circularize orbits over time. Elliptical orbits will slowly become more and more round as gravitational energy is transformed back and forth into other forms.
|
Reply With Quote