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baperez
2007-Sep-17, 09:10 PM
First let me say that I was thrilled to find such a high quality podcast about astronomy, and after listening to all 54 episodes, I have only been continually impressed. I have recommended this show to all my friends and family who have any interest in astronomy, and the podcast has also been referenced at the public observatory where I volunteer.

Ok, so now on to the commentary: Tidal locking is what happens when one side of a celestial body (or hemisphere) continually faces another. So that being the case, isn't it possible that Uranus already been tidally locked? It seems plausible that if Uranus had a slow initial rotation perpendicular to it's orbital path that it could have become tidally locked a long time ago. It also seems plausible that it could have been struck by a large object (as is already believed) and gave the planet its current "rolling" rotation. This would create an entirely new axis of rotation without the need for the energy required in realigning its former axis.

NHR+
2007-Sep-17, 11:34 PM
It also seems plausible that it could have been struck by a large object (as is already believed) and gave the planet its current "rolling" rotation. This would create an entirely new axis of rotation without the need for the energy required in realigning its former axis.

But don't all the moons of Uranus also revolve (at least very nearly) in its equatorial plane? How did that happen?

NHR+
2007-Sep-18, 12:47 AM
I posted this once before today, but I don't know where it went, so let's try again:

I just listened to this episode and one thing sounded a bit weird to me, I hope you don't mind my asking it here on this topic:

Which way is it that Uranus really rotates; rotational axis
A) always pointing (more or less) in the same direction (on the "firmament"), or
B) always pointing at the Sun?

It's a bit hard for me to find the right words to explain these two models, but perhaps this picture (that I drew myself just now;) helps you to understand what I mean:

http://img486.imageshack.us/img486/1843/uranus1od1.jpg

I've always thought that it was A), but in this episode I thought I heard Fraser and/or Pamela mention something like B) somewhere. What force makes a planet rotate (or is it revolve? Go around the Sun) this way? Though I might well have misunderstood something here, because (as you can probably tell) english isn't my native tongue...

Anyways, the show is awesome, I listen to it (almost) on a weekly basis. You guys got THE voices that I absolutely love to listen to... oh, and the topics are usually interesting, too... ;)