On July 4, 1054, a supernova (SN 1054) was observed by astronomers and stargazers across theNorthern Hemisphere, and possibly Australia. Its remnant, the Crab Nebula, is among the most-studied objects outside our solar system.
A supernova is one of the most explosive events in the universe. A supernova occurs when amassive star runs out of nuclear fuel (mostly hydrogen and helium). The core of the starcollapses, violently ejecting its outer envelope of material into space in a huge shock wave. These blast materials are the filaments still visible as the Crab Nebula.
The star that went supernova in 1054 was so massive that it left only a rapidly rotating ball ofneutrons called a pulsar. The Crab Pulsar is only about 20 kilometers (12 miles) in diameter, but has a mass greater than the Sun! The Crab Pulsar pulses, or spins, about 30 times a second.
SN 1054 was visible as a bright, glowing star for about two years! Astronomers in China, Japan, and what is today Iraq recorded the event. Some historians think that petroglyphs left byAncestral Puebloans may also have recorded SN 1054. Other historians think the oral tradition ofAboriginal Australians may also refer to SN 1054.