NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Equinox, eggs and other questions
From: Chuck Taylor
Date: 2002 Mar 16, 09:12 US/PACIFIC
From: Chuck Taylor
Date: 2002 Mar 16, 09:12 US/PACIFIC
> I always assumed the equinox was when the sun crossed the equator, but
> since taking a Cel Nav class I realize my naivete, and now assume that
> it must be more complicated than that ;) For instance, is it when the
> center of the sun crosses, or the lower limb, or what?
More precisely, it is the instant that an imaginary line
drawn from the center of the sun to the center of the earth
crosses the earth's equator.
> I figure the equinox will be between 19-00 and 20-00 UT (about 19-30 it
> looks like) since that's when the sun's declination hits zero. If I just
> fiddle with the increment tables to get a 0 deg dec, that's the equinox?
According to the University of Texas McDonald Observatory,
as posted at
http://www.stardate.org/nightsky/almanac/
the vernal equinox this year will occur at 1:16 pm CST
on March 20, which translates to 1916 UT. It's difficult
to get the precise moment from the Nautical Almanac.
Does anyone have a source that gives the time of the equinox
to the nearest second?
Chuck Taylor
Everett, WA, USA
