Quote:
Originally Posted by Allan_L
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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No you could not say this. The leaf would rotate aound the centre of the whirlpool. If it was rotating on its axis, it would spin independently of the whirlpool.
Likewise, the moon "rocks" on its axis whilst orbiting the barycentre of the earth/moon system. The earth rotates on its axis and is not locked to facing the earth/moon system barycentre...