Oh, and about your moon-sized-rock: we already track everything bigger than a few kilometers. So, sure it might kill us, but we'll have a hundred years or so to think about it.
And a few decades to think about being hit by a rock bigger the size of the Moon will make me feel better how?
Sings "Anticipation...anticipa-a-ation..." while searching for his Carly Simon CD's
emc"Being forced to write comments actually improves code, because it is easier to fix a crock than to explain it. "