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View Full Version : Discussion: Sedna Probably Doesn't Have a Moon



Fraser
2005-Apr-06, 07:51 AM
SUMMARY: When the planetoid Sedna was discovered last year, astronomers noticed that it had a very slow rotation speed, only turning once every 20 days. One way to slow the rotation of a planet is through the interaction of a moon, but detailed observations of Sedna with Hubble failed to turn up any evidence of a satellite. New observations by astronomers with the Harvard-Smithsonian Center for Astrophysics have revised Sedna's rotation speed to once every 10 hours, which is what you'd expect for an object this size. No moon is necessary.

View full article (http://www.universetoday.com/am/publish/sedna_no_moon.html)

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antoniseb
2005-Apr-06, 06:29 PM
I saw this paper in arXiv... it seemed like something I'd already read elsewhere a few months ago.

Greg
2005-Apr-07, 04:26 PM
There is an article posted quite recently on this forum by Fraser that may answer the question about both its redness and its orbit. The article refered to danger zones both in front of and behind gas giants as a means of trying to figure out whether or not Earth-like terrestrial planets could exist in those systems. A planet or planetoid in such a zone would be thrown out into the outer reaches of the solar system. So it would seem to me that perhaps sedna formed in Jupiter's neighborhood and therefore may have a composition similar to Mars, giving it its reddish hue. An unfortunate gravatational encounter with Jupiter may have accelerated it into its present orbit.