What happened here?

Origins

Main article: SN 1054

First observed in 1731 by John Bevis, the nebula was independently rediscovered in 1758 by Charles Messier as he was observing a bright comet. Messier catalogued it as the first entry in his catalogue of comet-like objects. The Earl of Rosse observed the nebula at Birr Castle in the 1840s, and referred to the object as the Crab Nebula because a drawing he made of it looked like a crab.^[4]

In the early 20th century, the analysis of early photographs of the nebula taken several years apart revealed that it was expanding. Tracing the expansion back revealed that the nebula must have formed about 900 years ago. Historical records revealed that a new star bright enough to be seen in the daytime had been recorded in the same part of the sky by Chinese and Arab astronomers in 1054^[5][6] Given its great distance, the daytime "guest star" observed by the Chinese and Arabs could only have been a supernova—a massive, exploding star, having exhausted its supply of energy from nuclear fusion and collapsed in on itself.

Recent analyses of historical records have found that the supernova that created the Crab Nebula probably occurred in April or early May, rising to its maximum brightness of between apparent magnitude −7 and −4.5 (brighter than everything in the night sky except the Moon) by July. The supernova was visible to the naked eye for about two years after its first observation.^[7] Thanks to the recorded observations of Far Eastern and Middle Eastern astronomers of 1054, Crab Nebula became the first astronomical object recognized as being connected to a supernova explosion.^[6]