Artist's impression of M83 (NGC 5236), a spiral galaxy in the constellation of Hydra, as it would appear through the Hubble Space Telescope (HST). M83 is about 27 million light-years away and has a diameter of around 30 thousand light years. A large proportion of the stars in M83 are young hot stars lying within the galaxy's spiral arms. The brighter ones amongst them are short-lived and die as supernovae. In our own galaxy such an explosion occurs about once every 30 to 50 years, but in M83 supernovae occur every 10 to 15 years, more frequently than in any other galaxy. The HST is an orbiting observatory which can image objects more sharply than existing telescopes on Earth.