Every now and then, a star dies in the most spectacular way imaginable. It detonates and in a matter of seconds, it outshines its entire host galaxy before fading back into darkness over the following weeks. These explosions, known as Type Ia supernovae, are some of the most violent events in the universe. They're also one of astronomy's most powerful measuring tools. Type Ia supernovae all explode with roughly the same intrinsic brightness. That makes them what astronomers call standard candles, if you know how bright something actually is and you can measure how bright it appears, you can calculate exactly how far away it is. It's the same principle as knowing a lighthouse emits a fixed amount of light and using its apparent dimness to judge your distance from the shore. The Crab Nebula captured by the Hubble Space Telescope (Credit : NASA/ESA) The problem is that the light reaching us from supernovae explosions isn't clean.…