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From: mink@cfa.UUCP (Doug Mink)
Newsgroups: net.space
Subject: Re: "At the moment Uranus's south pole points..."
Message-ID: <184@cfa.UUCP>
Date: Thu, 20-Feb-86 16:58:07 EST
Article-I.D.: cfa.184
Posted: Thu Feb 20 16:58:07 1986
Date-Received: Sun, 23-Feb-86 19:15:27 EST
References: <860217-235409-1418@Xerox>
Organization: Harvard-Smithsonian Center for Astrophysics
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> 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 International Astronomical Union, the final arbitter on the issue,
says the the South pole is that which is below (South according to the
Sun) the plane of the planet's orbit.  Astronomers have traditional
used the angular momentum vector (from the right hand rule) as the
North pole.  Using the IAU criterium, the sunward pole is South; using
the traditional criterium, it is North.  A confusing issue is that the
North pole of the magnetic field is in the sunward hemisphere, though
55 degrees away from the sunward pole.  When I had to refer to a point
denoting the sunward pole in an illustration of a paper I wrote, I just
called it "a pole of Uranus" in the figure caption (though on checking
my reprints I note that it got changed to South somewhere along the
line).
--
			-Doug Mink, aging hippy astronomer
			 Harvard-Smithsonian Center for Astrophysics
			 Cambridge, Massachusetts
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