The recent media attention to sunspot activity (however warranted) reminds me of a question I had long ago. Given the angular momentum and the slight 'wobble' of the earth, and remembering the apparently sporadic distribution of 'polar inversions' observed by geologists, I'm wondering how much the sun's magnetic field, and by extension the background galactic magnetic bias, could be influencing tidal, climate, tectonic and other terrestrial forces. It appears to me all the earth would need is a small 'nudge' and it's existing angular momentum would send it toppling end-over end, and we're so small compared to the sun so it SEEMS feasible to me. I'm sure that human observers would have noticed, but actual recorded history often proves to be rather incredulous and untrustworthy. Often attempts at truth or science are buried by popular opinion, and astronomical data goes back only so far . . .
Anyway, how likely is it the ice ages could be explained by the Earth 'realigning' so that polar regions would migrate over the surface of the earth?
In this model, rather than the entire earth being perfectly static and climate changing during recurrent ice ages, the data might be interpreted as more 'localized' disparages in temperature, with global averages remaining more or less constant and the earth's rotation causing the polar caps to 'migrate' across the surface. Can data disprove this? Is it POSSIBLE or is there some greater force I'm not considering which would keep the earth's wobble from becoming a topple?
Best Answer
How about zero? The geological evidence of the Ice Ages clearly says that, between the ice episodes, the ice did not move. It's just that the polar caps shrank. For instance, the extent of the last ice age is well mapped, and it is centered on the North Pole. It's just that the ice cap got a whole lot bigger as the planet got colder. When things warmed up the ice sheets retreated, but the center stayed at the North Pole.
While much older ice ages left their marks at different places on the current globe, you must keep in mind that, for the entire history of the earth, the continents have very slowly been sliding around, so (for instance) Antarctica used to be much farther north than it is now, and was correspondingly warmer.
As for
well, no. Just no. The forces required would be enormously more than the sun CAN apply by any mechanism that we know about. A small nudge just won't do it. The earth's rotation is not perfectly static (see the precession of the poles) but neither is it grossly unstable.
EDIT - It has been suggested that the anomalous rotations of Venus and Uranus might be examples of such a flip.
The case of Venus is not well-understood, and there are at least two different possibilities: peculiar formation due to perturbation during coalescence and tidal effects. In either case, the theories do not predict a flip on the timescale of 50,000 years. In the first case, no flip of the finished planet occurred, and in the second case the process took in excess of a billion years.
Uranus is even less useful, since it apparently occurred as a result of multiple impacts. On the one hand, the axial inclination is 98 degrees, so the planet is essentially lying on its side (compared to the rest of the solar system). More importantly, its satellites orbit in a plane which coincides with the rotational axis. This means that a shift in the orientation of the planetary axis cannot explain its current position, since such a shift would not have affected the orbits of its satellites.
END EDIT