May 18th in history:
On May 18th, 1927, more than 40 people, mostly children, died in the deadliest attack on a school in U.S. history, when a bomb went off at a school in Bath Township, Michigan. The explosion was planned by a school board member, who was upset that rising property taxes used to fund the schools were driving him out of his farm home.
Another man-made blast, by a rocket, sent the Apollo 10 mission into space on May 18th, 1969. It was the second manned spacecraft to orbit the moon, and the crew rehearsed procedures needed for the landing of Apollo 11 two months later.
Nature created a major explosion on this date in 1980, when the Mount St. Helens volcano in Washington State erupted. Fifty-seven people died in the explosion, which followed weeks of earthquakes and the venting of steam.