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From: @S1-A.ARPA,@MIT-MC.ARPA:FRIEDRITR%VAXJ.GATNET.MFENET@LLL-MFE.ARPA
Newsgroups: net.space
Subject: Precession of the equinoxes
Message-ID: <2856@mordor.UUCP>
Date: Tue, 30-Jul-85 13:24:35 EDT
Article-I.D.: mordor.2856
Posted: Tue Jul 30 13:24:35 1985
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From: FRIEDRITR%VAXJ.GATNET.MFENET@LLL-MFE.ARPA



I probably won't be the first or only one to point this out, but the precession
of the equinoxes has NOTHING to do with the fact that only one century year out
of four is a leap year.  The reason the Gregorian calendar adopted this
artifice is strictly due to the fact that the year is really 365.2422 days long,
and not 365.25 as would be required if every fourth year were a leap year,
including the century years.

However, the respondent was right in saying that the precession of the
equinoxes is probably the phenomenon the original questioner is referring to.
I don't know how precisely this is calculated, or even how precisely it CAN
be calculated, due to the complicating factors of solar and lunar gravity,
as well as that of the planets, and the fact that the interior of the Earth
is not a rigid solid.  The precession of the equinoxes is the same precession
seen in any other gyroscope, except for the above factors.

Terry