Thursday, December 22, 2005

Apparent Santa Wandering:

I have been attending some discussions lately where we discuss the upcoming International Polar Year activities.

One of the NASA boffins was going on about how many poles there are: the Moon has poles where we hope to find water for lunar bases, Mars has polar caps with water and carbon dioxide ice, and Uranus has poles that ocasionally point at the Sun. Heck, even the Sun itself has poles, although they aren't very cold.

The talk about the Sun having poles made me realize that because poles are simply where the axis of rotation intercepts the surface, there are bodies out there that have no poles in the usual sense: the chaotic tumblers. These are bodies that are oddly shaped enough that they are dynamically unstable, and do not rotate regularly. You may have seen or even done the old physics demo where a heavy textbook is held shut with rubber bands, and then tossed while being spun around various axes. Spinning the book around the short and the long axes works fine, but that intermediate one... there's that unstable wobble. Now imagine an enormous rock doing this in space. Hyperion, one of Saturn's moons, is a chaotic tumbler, and the recent visitor Toutatis (about which I posted last year), is another.

Now imagine if Santa were on one of these bodies, having to move his toy factory every few days.

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