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Re: Impacts and ETs
Tip over? Uranus currently has an inclination of almost 90 degrees. Do you
mean like that? Or our inclination stays the same while "tipping"?
Yes, sorry, I confused that in my last post. Polar wander is meant -- the
process in which the angle between the Earth's rotation axis and the
ecliptic stays the same. Rotating bodies are most stable when the mass is
concentrated on the equator. Various processes (continental drift,
reorganizations of mantle and core...) change the mass distribution of a
planet, giving it a reason for fast and far polar wander.* The attraction of
the Moon is greater than all such imbalances that the Earth can produce in
itself, and therefore polar wander on Earth is either nonexistent or
* The university library over here has an extraordinarily ignorant book from
the 50s (read: before plate tectonics was discovered). The author did not
accept continental drift and tried to explain all of geology and
paleontology, especially the mass extinctions (including the frozen mammoths
& stuff), by a series of catastrophic polar jumps.
** I don't know what has become of the idea, published last year or so, that
polar wander on the scale of 16 to 20° happened in the Campanian -- taking
two million years.