March 23, in "celebration" of a big asteroid that passed Earth at twice the distance from the moon.
Of course, that can't compare to the one that passed at twice the distance of a communications satellite Monday, with absolutely no warning. We will always remember March 2, 2009 as the day we almost ended global warming in one swell foop. And California.
Speaking of near misses, did you know that in March 2005, workers at a nuclear weapons facility almost accidentally exploded a nuclear bomb in Amarillo Texas?