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View Full Version : Uranus' tilt/ moons question



spacer62
2010-Dec-31, 02:09 AM
Are Uranus' satellites orbiting in the same plane as the planet's equator? If the 'giant impact' theory explains the tilt of the planet, what about the orbits of the satellites, or were they formed as a result of the collision? BTW, I'm Doug Devers, a newbie to this forum...

antoniseb
2010-Dec-31, 03:54 AM
Hi Doug, welcome.

IIRC, the inner moons are roughly coplanar with the planet's rotation, and the outer moons are not.

Somes J
2011-Jan-04, 08:48 AM
I have a question of my own about this. If the sattelites are in an equatorial orbit of Uranus, that would mean their orbit is heavily inclined to the sun ... shouldn't the Kozai Effect be massively pumping their eccentricities? Presumably this hasn't happened, as highly elleptical orbits are never mentioned as a feature of Uranus's sattelite system. Is the effect just really weak that far from the sun?

Romanus
2011-Jan-04, 10:45 AM
Uranus's outer satellites seem to be strongly perturbed; its inner ones, though, are apparently too deep in its gravity well to be much affected.

frankuitaalst
2011-Jan-04, 10:14 PM
Uranus's outer satellites seem to be strongly perturbed; its inner ones, though, are apparently too deep in its gravity well to be much affected.
Indeed , the innermost moons seem to be well preserved against the Kozai effect while they're so close to Uranus . The link herunder gives some animations and data about changes in inclination and eccentricity of these moons.
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1240424172/2#2

spacer62
2011-Jan-05, 03:01 AM
Thanks for the replies. I suppose my question now becomes: Why are the inner moons coplanar to Uranus' rotation? Were they likely formed when the planet 'tipped over'?

frankuitaalst
2011-Jan-09, 07:07 PM
Thanks for the replies. I suppose my question now becomes: Why are the inner moons coplanar to Uranus' rotation? Were they likely formed when the planet 'tipped over'?
IIRC one of the theories is that Uranus got a collision with an earth sized body early in the history of our solar system , resulting in its unusual axial tilt ( one source : Murray & Dermoot : Solar system dynamics) . Don't know if the moons already were present at that time or may have been created at that occasion . My interpretation is that if the moons already were the present they can gradually have been drawn into the equatorial plane due do tidal forces.
As far as I know the Uranian moon system is tidally "matured" .

WayneFrancis
2011-Jan-12, 02:31 AM
Indeed , the innermost moons seem to be well preserved against the Kozai effect while they're so close to Uranus . The link herunder gives some animations and data about changes in inclination and eccentricity of these moons.
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1240424172/2#2

FYI the link you provide is declined by the web server.

frankuitaalst
2011-Jan-12, 04:22 PM
FYI the link you provide is declined by the web server.
this is funny . The link works perfectly for me .
You can try the following : goto www.orbitsimulator.com , choose message board and then goto the thread uranian moons

frankuitaalst
2011-Jan-12, 10:30 PM
I'm not sure if the theory and calculations of Beletski in the eighties in the link herunder are still supported
http://adsabs.harvard.edu/full/1981CeMec..23..371B
Beletski seems to state in this article that Uranus may have had a strong retrograde rotation in the past . Due to tidal effects the axis may have flipped over to the present 98 inclination .

WayneFrancis
2011-Jan-13, 12:10 AM
this is funny . The link works perfectly for me .
You can try the following : goto www.orbitsimulator.com , choose message board and then goto the thread uranian moons

The message board errors too...there seems to be some type of authentication going on. IE its like it wants me to be logged in but doesn't issue a challenge/response

tony873004
2011-Jan-15, 12:31 AM
The message board errors too...there seems to be some type of authentication going on. IE its like it wants me to be logged in but doesn't issue a challenge/response
You shouldn't have to be logged in to read the threads. You only need to log in to post. Can you try it with a different browser? The link works for me on IE, Firefox, and Safari.