About 6500 years ago, a star in the constellation of Taurus exploded as a supernova. On July 4, 1054 CE, light from this explosion reached the Earth and was observed by Chinese astronomers, who made a record of their observation. The Crab Nebula has been identified as the detritus from the explosion; and in the approximately 960 years since the sighting of the supernova, the nebula has been expanding at a rate that roughly corresponds to its age.

For more information on how to do this problem, and for tables of relevant data, see www.canismajor.ca.