Supernova (SN 2002dd) in the Hubble Deep Field, April 10, 2003. Hubble Space Telescope observations of a pair of very distant exploding stars, called Type Ia supernovae, provide new clues about the accelerating universe and its mysterious dark energy. Astronomers used the telescopes Advanced Camera for Surveys to help pinpoint the supernovae, which are approximately 5 billion and 8 billion light-years from Earth. The farther one exploded so long ago the universe may still have been decelerating under its own gravity.