Gas giants and axial tilts

[ajtribick]

Are the axial tilts of the gas giant planets also very chaotic like those of the terrestrials - apparently Mars goes through stages when the axis tilt is over sixty degrees, and if Earth didn't have the moon this would also occur - Venus and Mercury seem to be stabilised by solar tides. But I haven't seen anything about the tilts of the gas giants - presumably the satellites are too small in comparison to provide stability, but presumably it's a lot harder to change the rotation axis of a large planet.

[MKruer]

You might find this paper interesting. In a nutshell the tilt of a Gas Giant is more or less set by the events that formed it. However like everything nothing is for certin.

http://ourworld.compuserve.com/homepages/dp5/pole2.htm

One thing I can say that might be a valid example is;

Think of a spinning top. A top that spins faster is inherently more stable then one that spins slower. So with this logic, a Gas Giant is more stable because it?€™s spinning a lot faster. However some time in the future we might come across a slow turning Gas Giant in which the tilt is more chaotic.

[Malenfant]

Think of a spinning top. A top that spins faster is inherently more stable then one that spins slower. So with this logic, a Gas Giant is more stable because it?€™s spinning a lot faster. However some time in the future we might come across a slow turning Gas Giant in which the tilt is more chaotic.

As far as I can understand it a gas giant won't change its tilt easily even if it is "slowly spinning" (ie a rotation period much longer than 24 hours. Uranus and Neptune are around 20 and 24 hours IIRC?), because it's just so darn massive. That makes it a lot harder to affect that a piddly little terrestrial planet .

[MKruer]

Think of a spinning top. A top that spins faster is inherently more stable then one that spins slower. So with this logic, a Gas Giant is more stable because it?€™s spinning a lot faster. However some time in the future we might come across a slow turning Gas Giant in which the tilt is more chaotic.

As far as I can understand it a gas giant won't change its tilt easily even if it is "slowly spinning" (ie a rotation period much longer than 24 hours. Uranus and Neptune are around 20 and 24 hours IIRC?), because it's just so darn massive. That makes it a lot harder to affect that a piddly little terrestrial planet :).

DOH! Should have checked my figures first; however that being said, how do we know for sure that Gas Giants can?€™t tilt on their own just like the smaller planets? Uranus might be an example of this. The truth is that we simply have not observed the planets long enough to know for sure.

[Malenfant]

DOH! Should have checked my figures first; however that being said, how do we know for sure that Gas Giants can?€™t tilt on their own just like the smaller planets? Uranus might be an example of this. The truth is that we simply have not observed the planets long enough to know for sure.

By smaller planets, you mean like Mars? Its tilt changes so much because it (a) doesn't have a big stabilising moon like we do, and (b) is more affected by Jupiter's gravitational influence.

Earth may have shifted quite a bit - there was an idea (dunno if it's accepted) that around the Cambrian Explosion the earth's axis shifted very rapidly (geologically speaking) from about 70 degrees to about 25 degrees because of some aspect of the rotation of its core relative to the mantle above it. But it's reasonably stable since then (if that happened).

Venus' tilt apparently got so high (about 180 degrees) largely due to the effect of solar tides on its very dense atmosphere.

And Mercury barely has any tilt because it's so close to Sol and strongly affected by solar tides.

So I'm not really seeing how any ofthe smaller planets are "tilting on their own" - the gas giants are too far to be tidally influence by the sun, or even by eachother.

[Malenfant]

have some dingleberry pie

I don't know what your problem is, but you have been reported for clogging up the forum with your crap. Hopefully you'll be banned.

[Bowserjoe]

hopefully

[Chuft-Captain]

Earth may have shifted quite a bit - there was an idea (dunno if it's accepted) that around the Cambrian Explosion the earth's axis shifted very rapidly (geologically speaking) from about 70 degrees to about 25 degrees because of some aspect of the rotation of its core relative to the mantle above it. But it's reasonably stable since then (if that happened).

Sorry if this is slightly off the topic, but from what I understand the earth's magnetosphere periodically does a "flip" -- magnetic north becomes south and visa-versa. Can't remember the source (probably. Discovery Channel ), but I think it had something to do with geologists research on the alignment of ferric-oxide strata in rocks.

Anyone know anymore on this?
True or false?
Theories on what causes it, etc...

[selden]

Yes, it does.

A Web search for
earth magnetic field reversal

will lead you to detailed explanations.

[Chuft-Captain]

Thanks Selden,

I particularly enjoyed this animation, for anyone whose interested:
http://www.pbs.org/wgbh/nova/magnetic/reversals.html