Quote:
Originally Posted by Allan_L
Does the Moon rotate on its axis?
Or is it a captured movement of the Earth's influence.
I know it always presents the same face to the Earth, but I believe there may be differences of opinion on this area of lunar physics.
Picture a leaf caught in a whirlpool. It may always present the same face to the centre of the whirlpool, but could you really say that leaf is rotating on its axis?
What do you reckon?
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I believe it rotates at the same rate as it revolves [around the earth]. According to modern genesis theories, Earth was hit by a large body. This blew a large chunk off which became the Moon. The spin rate was conserved (conservation of angular momentum) in the matter which formed the Moon. So the spin rate for the Moon and that of Earth should be similar.
As for this statement, "a captured movement of the Earth's influence"...the Moon is most definitely captured by the Earth's influence, likewise, the Earth is captured by the moon's influence. This extends to all matter - and energy - in the entire Solar System, Milky Way, all Galaxies...everything that has mass...and if you subscribe to Einstein's equations, that must include energy too (energy momentum tensor).
There is only one Spacetime and we are all embedded in it. It's features are governed by both the distribution of mass and energy as well as what that mass and energy are doing. Mass and energy literally create the spatial and temporal separation, but an "influence", from one body to another, is also governed by the degree of spatial and temporal separation (distance and time).
In modern jet engines, large sections may be thermodynamically coupled; you cannot affect one without affecting all coupled parts, even though they are not physically connected, and yet they spin freely. Likewise, you cannot change the mass, velocity, spin etc (the Energy Momentum Tensor) without affecting the spatial and temporal properties of Spacetime (the field), not just because they are balanced, but because they are the same system. Energy/Mass, and, Space/Time, are not separable, they are mutually supportive...you could almost say they are different properties of the same thing.