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From: @S1-A.ARPA,@MIT-MC.ARPA:dsmith%hp-mars.csnet@csnet-relay.arpa
Newsgroups: net.space
Subject: Re: calendar
Message-ID: <2901@mordor.UUCP>
Date: Thu, 1-Aug-85 06:07:53 EDT
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Posted: Thu Aug  1 06:07:53 1985
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From: David Smith <dsmith%hplabs.csnet@csnet-relay.arpa>

> 	Yea.  We have a leap second periodically to even out the flaws in
> the Gregorian calendar.  Just had one this year, in fact.

The leap second is not to compensate for the Gregorian calendar, but for
the fact that the earth's rotation on its axis is slowing down.  The
standard second is defined as 1/86,400 of a day in 1900 (I think averaged
over the days of that year).  The earth is rotating enough slower now to
require leap seconds to keep the astronomical day and atomic clocks in
sync.

I am surprised that the precession of the equinoxes is described as a
change in the ecliptic.  The ecliptic stays (relatively) fixed;  it is the
earth's axis which precesses, carrying the celestial equator with it.

		David Smith
		ucbvax!hplabs!dsmith