Missed it by THAT Much: 334,000 miles

In a preview of one of the few doomsday scenarios qualifying as not "if", but "when", an asteroid 500-2000 feet in diameter will pass within 350,000 miles of the Earth some time this week. Apparently such events are fairly common, happening every 5 years or so, but because their impact would be so devastating for us, astronomers take a close look. Every 37,000 years on average that impact occurs, and it tends to destroy a high percentage of the life on earth when it does so. The worst, occurring before the vaunted Cambrian Explosion during the Proterozoic Era, wiped out 95% of life on earth. Those craters on the moon are not volcanic, they are from asteroid impact. One day, it will happen here again.