OK, not new. 12 million or so years ago. Anyway, up near the Big Dipper is M82, the Cigar Galaxy. After about 12,000,000 years the light of a Ia supernova has reached Earth. (that’s type 1-a) You’ll need a telescope of binoculars to see it. Here’s where it is in the night sky.As a type Ia supernova, it isn’t caused by a large star dying and collapsing. Instead, it is caused by a white dwarf accumulating enough mass to become unstable, or 2 white dwarfs colliding (rare). Because the accreting method leads to the mass of the white dwarf increasing until it reaches the Chandrasekhar mass (about 1.44 solar masses), where the temperature of the star reaches the temperature needed to fuse carbon. Once this happens, a lot of the star explodes, releasing about 1-2 × 1044 J of energy. This leads to a standard peak luminosity, which can be used to measure the distance to the supernova (they are standard candles).