NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Dec on equinox day
From: Robert H. van Gent
Date: 2025 Mar 29, 04:45 -0700
From: Robert H. van Gent
Date: 2025 Mar 29, 04:45 -0700
Hi,
The wobbles in the apparent geocentric ecliptic latitude of the Sun are due to the fact that the Moon and the other planets in our solar system do not move exactly in the ecliptic plane but can be either slightly above or below the ecliptic plane.
These perturbations are accounted for in solar tables such as those of Simon Newcomb which were used until the 1970s in the nautical and astronomical almanacs.
https://archive.org/details/06AstronomicalPapersPreparedForTheUse/page/17/mode/1up
cf. pp. 17-18 & Table 7. The largest terms stem from the Moon, Venus and Jupiter.
rvg
