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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.space
Subject: Re: "At the moment Uranus's south pole points..."
Message-ID: <399@utastro.UUCP>
Date: Fri, 21-Feb-86 16:28:45 EST
Article-I.D.: utastro.399
Posted: Fri Feb 21 16:28:45 1986
Date-Received: Mon, 24-Feb-86 05:46:37 EST
References: <860217-235409-1418@Xerox>
Organization: U. Texas, Astronomy, Austin, TX
Lines: 16
Summary: right hand rule

In article <860217-235409-1418@Xerox>, Murray.pa@XEROX.COM writes:
> How do I tell which end is North and which is South? I assume that the
> "North" pole of Mars is the one that's pointing roughly parallel to the
> North pole of Earth. That doesn't transfer to Uranus very well.

The angular momentum vector of the Earth points toward the North Celestial
Pole.  Put it another way, looking down on the Earth from a point above
the North Pole the Earth's rotation is counterclockwise.  Therefore,
by convention, the north pole of any planet is that pole from which
the rotation appears counterclockwise.
-- 
"Ma, I've been to another      Ethan Vishniac
 planet!"                      {charm,ut-sally,ut-ngp,noao}!utastro!ethan
                               ethan@astro.UTEXAS.EDU
                               Department of Astronomy
                               University of Texas