Quote:
Originally Posted by Quark
Hi Geoff,
As the Moon rotates on it's axis it exhibits small apparent oscillations or libration, your images clearly demonstrate this effect.
Nutation is an apparent slight nodding in the axis of rotation.
Tidal forces exerted by the Moon on the Earth cause the Earth to Nutate.
As the Moon orbits the Earth it experiences a variation in the inclination of it's orbit, relative to the ecliptic, of between 5 degrees and 5 degrees 18 minutes with a period of 173 days. This results in a slight apparent nodding motion of the Moons rotational axis relative to Earth, similar to nutation.
This would thus provide you with the potential to image slightly different regions near the poles.
Regards
Trevor
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Thx very much for the detailed explanation.
I now know what you mean, and have seen this " nodding" in examples of libration in the past.
Cheers....and I hope the skies are clear where you are.
Geoffro.