Today in History: Halley's Comet

On this day (April 10) in 837, Halley’s Comet made its closest approach to the earth at 3.2 million miles. That’s approximately 13 times farther from the earth than the moon is. The idea of a comet (or similar celestial body) hitting the earth has long fascinated and worried people. (After all, there are some big examples of catastrophic damage being done from such a strike.)One of the best fictional accounts of such a strike is Lucifer’s Hammer, by Jerry Pournelle and Larry Niven.