Crab Supernova was a supernova that was widely seen on Earth in the year 1054.
A supernova is a stellar explosion that briefly outshines an entire galaxy, radiating as much energy as the Sun or any ordinary star is expected to emit over its entire life span, before fading from view over several weeks or months.
Crab Supernova was so bright that, it was easily visible to naked eye in daylight for 23 days and in the night sky for 653 days. The progenitor star was located in the Milky Way galaxy at a distance of 6,300 light years and exploded as a core-collapse supernova.
The cloudy leftovers of SN 1054 are now known as the Crab Nebula.