Number 20 (Story #4), February 5, 1991 by Phillip F. Schewe and Ben Stein THE DISTANCE BETWEEN THE LARGE MAGELLANIC CLOUD and Earth has been measured more accurately than ever before. Observations of the ring of gas surrounding supernova 1987A---gas expelled by the precursor star thousands of years ago and later heated up by the supernova---using the Hubble Space Telescope to provide the angular diameter of the ring and using the International Ultraviolet Explorer satellite to provide the ring's diameter in space have resulted in an Earth-SN1987A distance calculation of 169,000 light years. This distance measurement technique may provide a better yardstick for measuring distances in the cosmos. (Physics Today, Feb. 1991.)