Volume 40 number 1 (2012)
The concept of “supernova,” a class of exploding stars more than 100 times the luminosity of an ordinary nova, was introduced almost eighty years ago. Over that time the physics of supernovae has matured into a rich field of study with the identification of several types of explosions and models to explain many of the observations. While there has not been a supernova visible in our Galaxy in over 300 years, only twenty-five years ago a naked-eye supernova, SN 1987A, was intensively studied in a companion galaxy to the Milky Way. Type Ia supernovae have proven to be a reliable way to estimate cosmological distances and these standardizable “candles” have greatly improved the estimate of the local expansion rate of the universe. Pushed to great distances these supernovae have demonstrated that the universe is accelerating, a discovery recognized with the 2011 Nobel Prize in physics.