Re: moonrise and time offset
From: Brian Tung (brian_at_isi.edu)
Date: 08/04/04
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Date: Wed, 4 Aug 2004 22:25:37 +0000 (UTC)
Tom Rankin wrote:
> The basic reason is because the Moon does not orbit the Earth in the
> same plane as the Earth orbits the Sun. Thus the Moon's declination can
> change rapidly from day to day, or slowly, depending on where the moon
> is on the celestial grid. And the declination change can have a large
> effect on rise/set time.
Although this is basically correct, I'm going to pick a nit and mention
that I don't think you mean the ecliptic plane you mean, but that of
the celestial equator. If the Moon orbited in the equatorial plane, it
*would* have the same declination (0 degrees, geocentric) all the time.
If it orbited in the ecliptic plane, its geocentric declination would
vary between -23.44 and +23.44.
Brian Tung <brian@isi.edu>
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