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From: paula@bcsaic.UUCP (paul allen)
Newsgroups: sci.astro
Subject: Re: Moon crater viewing
Message-ID: <735@bcsaic.UUCP>
Date: Fri, 17-Oct-86 20:26:24 EDT
Article-I.D.: bcsaic.735
Posted: Fri Oct 17 20:26:24 1986
Date-Received: Tue, 21-Oct-86 21:13:33 EDT
References: <90@ritcv.UUCP>
Reply-To: paula@bcsaic.UUCP (paul allen)
Distribution: net.astro
Organization: Boeing Computer Services AI Center, Seattle
Lines: 27
Keywords: libration moon craters wobble
Summary: Its called 'libration'


>	I hate to taunt you all if this is not true, but I seem to
>remember reading that at a certain time, on a certain day, once a year,
>the top edge of a crater on the moon's dark side is visible. If this is
>true and anyone knows about it, (i.e. what day and time), could they
>please pass the info on to me. I've always wanted to see this event, but
>forgot to save the story (if indeed I did read it).
>
>                   Thanks in advance,
>                            Whitey Johnson.

We can actually see somewhat more than 50% of the moon's surface from
the Earth because the moon appears to wobble back and forth a little bit 
as it orbits around us.  I don't think the period of the wobble is as long 
as a year, though.  Why don't you take your telescope out in your backyard
and watch the moon regularly for a few months?  If you make sketches (or
take pictures), I bet you'll be able to determine the period.

Have fun!
Paul Allen

-- 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Paul L. Allen
Boeing Computer Services Artificial Intelligence Center
...!uw-beaver!ssc-vax!bcsaic!paula