Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Janet on 19/10/2008 13:19:01

Title: Do all planets rotate like Earth?
Post by: Janet on 19/10/2008 13:19:01

Janet asked the Naked Scientists:

I wanted to know if all planets rotate as well as revolve. If not, which
planets?

What do you think?

Title: Do all planets rotate like Earth?
Post by: dentstudent on 19/10/2008 13:40:59

There are some differences in the rotational direction in the planets - all but 2 rotate anti-clockwise like the earth. Venus has its axis of rotation (ie its poles) in its side, and so is effectively "rolling" around in its orbit rather than spinning. Uranus has completely flipped and so has its axis in a similar orientation to earth, but is spinning the other way (ie clockwise). I think (but someone else should qualify) that mercury is close to being tidally locked to the sun which means that there is always one side of Mercury that is facing the sun, or at least a very long day length if it is not fully locked.

http://en.wikipedia.org/wiki/Tidal_locking

Title: Do all planets rotate like Earth?
Post by: Soul Surfer on 19/10/2008 13:42:24

in general all astronomical bodies rotate but the rotation rate can vary quite a lot.  Jupiter the largest planet rotates very quickly only taking about 10 hours to rotate.  This is so fast that it is notcably flattened.  On the other hand Venus takes longer to rotate than it does to revolve around the sun

Title: Do all planets rotate like Earth?
Post by: chris on 20/10/2008 07:53:58

Uranus rotates on its "side"; originally scientists thought this was the consequence of some kind of cosmic collision. More recent models of the gestation of the solar system, however, suggest that it might instead be a "resonance" effect resulting from the gravitational interactions of the nascent (forming) planets as they jostled for position.

Title: Do all planets rotate like Earth?
Post by: dentstudent on 20/10/2008 09:11:50

My mistake about Uranus - sure I heard it from an astronomy podcast. Anyway, here is a link that shows the angle of the axis of Uranus...

http://www.planetary.org/blog/article/00000553/