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From: wyatt@cfa.UUCP (Bill Wyatt)
Newsgroups: net.space
Subject: Re: Uranus's axis
Message-ID: <179@cfa.UUCP>
Date: Fri, 7-Feb-86 10:50:37 EST
Article-I.D.: cfa.179
Posted: Fri Feb  7 10:50:37 1986
Date-Received: Tue, 11-Feb-86 04:34:04 EST
References: <111@valid.UUCP>
Distribution: net
Organization: Harvard-Smithsonian Center for Astrophysics
Lines: 20

> I know that Uranus's axis of rotation is tilted ~90 degrees from the
> normal, perpendicular-to-ecliptic axis.  This means that the axis
> lies in the plane of the ecliptic, but which way does it point?  
> Does it point at the sun, or is it tangent to the orbit, or some
> angle in between?
> John Oswalt (..!{hplabs,amd,pyramid,ihnp4}!pesnta!valid!jao)

Well, it depends...
Just as Earth's axis points at one point (more or less the star Polaris),
Uranus's pole points at one place (I don't know just where). As Earth
goes around the sun, the angle between the sun and the Earth's axis
changes, causing seasons. The same thing happens to Uranus, except the
Uranian `year' is ~84 years. The extreme axial tilt (currently the `north'
pole is pointing essentially right at the sun) means that 1/2 of the
planet (i.e. the opposite polar region) spends ~21 years in total darkness.
Must make for some interesting climate cycles!
-- 

Bill    UUCP:  {seismo|ihnp4|cmcl2}!harvard!talcott!cfa!wyatt
Wyatt   ARPA:  wyatt%cfa.UUCP@harvard.HARVARD.EDU