> > > day, the declination of the moon changes a lot every day, > > since it goes through the cycle from maximum to minimum > > declination every month, while the sun takes a whole year > > to go through that cycle. > > Yes, I knew that. And I heard as well that the moon's > extreme declinations vary from month to month, being > greatest (around +/- 28 deg) in winter and shortest in > summer (around +/- 18 deg), but I do not know for sure > what happens with the extreme declinations on the equinoxes, > if something happens... Is it always +/- 23.5 deg ? It > seems so, but... > > Regards, > > Anselmo >
This information is from the 2006 Astronomical Calendar by Guy Ottewell: The plane of the moons orbit is inclined relative to the ecliptic, but it precesses, making a complete revolution in 18.61 years. The inclination is about 5 degrees. This year, the orbit is aligned so that the moons inclination adds to the obliquity so that the moon can reach 28.72 degrees declination. Back in 1997, one half precession period ago, the moon could only reach 19 degrees as the maximum declination. So the moons declination on the equinox depends both on the particular alignment of the orbits and where the moon is in its orbit at the monent of equinox. Since the moons orbit is not synchronized with the equinox, there is no requirement that it be at any special place when the equinox happens, thus is not at a special declination. Maybe somebody else can add a clearer explanation. --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
