NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Dec on equinox day
From: Frank Reed
Date: 2025 Mar 20, 06:23 -0700
From: Frank Reed
Date: 2025 Mar 20, 06:23 -0700
The equinox occurred about four hour ago. Most sources say 09:01 UT. The Sun's Declination was zero at 09:02 UT. Anyone care to explain the difference?
What is the Sun's Declination now? For about a month around the equinox, the Sun's rate of change of Dec is about one knot. That is, the subSun point, where the Sun is exactly at the zenith, is drifting north at one minute of arc per hour. It is also rocketing west at 900 knots, but we won't worry about that for now. The current time, as I write this, is about 13:26 UT so 4.4 hours after "dec zero". That implies the Sun's Declination would be 0° 04.4' N. That's only an estimate. How good is it?
Frank Reed
