According to some estimates, we're millions of years overdue for another planet-buster on the order of the so-called "K-T Event". Und andere boojums, perhaps, but evidence of past catastrophe is strong. That we seem to have the possibility of intervening in such things is what's new under the Sun... --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .