Keplers Supernova (SN 1604)
One night in October 1604, a bright new star appeared in the Constellation of Ophiuchus, it became so bright it was visible even during the day, it lasted for a few weeks, then slowly began to dim, visible for a few more months until fading away.
This was a Supernova, 20,000 light years from Earth in our Milky Way, and witnessed by Johannes Kepler, to whom it is now known after. It was also witnessed by Galileo and a variety of other eminent scientists of the era, and seen as evidence and proof that the heavens were not fixed in place.
Over 400 years later, and that supernova explosion has produced the nebula. This supernova was a type 1a, theorised to be a red giant star with a now dead white dwarf companion. The white dwarf began to pull material from the red giant which eventually collapsed into a neutron star in an explosion that lit up most of the Milky Way galaxy.
Most of the more recent supernova witnessed have occurred on other Galaxies, they are so bright, as to be visible even over 50-100 million light years. The closest was in 1987 (SN 1987A) in the large magellanic clouds, dwarf galaxy that orbits our Milky Way Galaxy.
