Yesterday I showed M101 with a supernova, I've put the SN image here with it indicated. It was a type 1a SN which are important due to what causes them. They're caused by either a white dwarf accreting too much mass or merging WD stars. Since the mass is the same each time type 1a supernova all have roughly the same intrinsic brightness. This makes them excellent standard candles for measuring distance. They're bright enough that we can use them out to about 2200 Mpc or 7.1 billion light years.
Teacher, astronomer, political scientist and father. I wrote a book once: http://evl.link/df
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!