Close Supernova

Astronomers were lucky enough last week to catch a supernova in the earliest stages of the explosion. This supernova is a Type 1a, the kind astronomers use to measure distances in the universe. It turns out all explosions of this type reach the same absolute magnitude, so the observed magnitude can be directly related to distance. Astronomers believe a Type 1a occurs when a white dwarf becomes too massive to support itself and explodes.

This is the closest supernova observed since 1986, and astronomers have already noted details in the process they've never seen before. Not to worry, though-- this supernova is still 21 million light-years away, in the Pinwheel Galaxy.