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Re: Uses of almanacs for astrology
From: Lisa Fiene
Date: 2004 Oct 21, 06:47 +1000
From: Lisa Fiene
Date: 2004 Oct 21, 06:47 +1000
George, Actually the earth is an oblate spheroid, sort of squashed at the top and stretched at the equateor, and the moon librates (quite a lot) in its orbit. Lisa > > ==================== > > This is due to the ellipsoidal shape of the Earth. If the Earth were a > uniform sphere, then the gravitational attraction of the Moon (and, to a > lesser extent, the Sun) would act exactly through the Earth's centre. But > the Earth's ellipsoidal shape upsets that simple geometry. You can think of > the Earth as a sphere with a sort of "spare tyre" added round its equator. > The total attraction on that extra ring does not pass exactly through its > centre, so now there's a slight torque which is trying to align the Earth's > equator with the averaged plane of the Moon's orbit. The Moon's orbit > wobbles about a lot,