A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2017 Jul 31, 04:13 -0700
Why the definition of Equinoxes demands the Sun's longitude to be equal to either 0° or 180°?
The actual length of the day or night depends directly on the Sun's declination (rather than on its' longitude), so why not Dec == 0° then?
Yes, I know that the orbital plane (of Earth) wobbles a bit (because of other planets' gravitation), but it is immediately translated into Sun's apparent declination, so I'm puzzled. Is it just for the simplicity of calculations (of the equinox of date)?
Thank you in advance.