NetNews Usenet Archive 1992 #19/NN_1992_19.iso/spool/sci/math/10870

Internet Message Format | 1992-09-02 | 1.7 KB

Path: sparky!uunet!mcsun!uknet!cam-cl!cam-cl!cet1
From: [e-mail] (C.E. Thompson)
Newsgroups: sci.math
Subject: Re: Calendar
Message-ID: <[e-mail]>
Date: 2 Sep 92 16:24:40 GMT
References: <[e-mail]>
Sender: [e-mail] (Piete Brooks)
Reply-To: [e-mail] (C.E. Thompson)
Organization: U of Cambridge Computer Lab, UK
Lines: 25

In article <[e-mail]>,
[e-mail] (ilan vardi) writes:
|> There is a high probability of a lunar eclipse during Passover.  In
|> fact, given that non Israeli Jews celebrate Passover on two successive
|> evenings, the probability that some passover celebration in the world
|> occurs during a lunar eclipse must be quite high (perhaps > 1/10).
|> This does not hold for Easter since the computation uses a pseudo
|> lunar computation (the Paschal moon).

Apologies for continuing this thread in sci.math, in which it is hardly
appropriate, but I couldn't let that last remark pass.

Both the Gregorian calendar (w.r.t. the date of Easter) and the Jewish
calendar use fictitious moons, and there is no significant difference
in the accuracy with which they simulate the real one. The reason that
Easter is less likely to coincide with the full moon (and hence an
eclipse) is that is postponed from a particular point in the lunar
cycle to the next Sunday. The corresponding variation in the Jewish
calendar is only the 1 or 2 days by which the start of the year
sometimes has to be shifted to avoid certain religious festivals
falling on particular days of the week.

Chris Thompson
JANET:    [e-mail]
Internet: [e-mail]