Astronomy is one of the oldest scientific disciplines. Observations of the sky by ancient civilizations provided important milestones. Solar and lunar eclipses were prominent events as were the discovery of comets and "guest stars," now recognized to be supernovae. These "guest stars" were observed by Chinese, Japanese, and Korean astronomers (or astrologers) for the last two millennia and possibly were sighted by the ancestors of the native Americans of the U.S. Southwest. The prime example of this was the Crab supernova in 1054, a drawing of which can be seen at the Chaco Culture National Historical Park in New Mexico.