The event you're describing is the famous SN 1054 supernova, which occurred in the year 1054. It was so bright that it was visible during the day for several weeks and was recorded by Chinese and other astronomers. This supernova was a significant event for several reasons:
* The Crab Nebula: The explosion left behind a beautiful and expanding cloud of gas and dust called the Crab Nebula. This nebula is a popular target for astronomers, providing valuable insights into the life cycle of stars.
* Confirmation of Stellar Evolution: The SN 1054 event helped confirm the idea that stars can explode at the end of their lives, a key aspect of stellar evolution.
* Historical Records: The detailed observations of the supernova by Chinese and other astronomers provide valuable historical data for studying supernovae and their effects.
So, the "guest star" that exploded over China in 1054 was actually a supernova, a spectacular event that marked the end of a massive star's life and left behind a stunning and informative astronomical object.