The crab nebula, also known as M1, is the gaseous remnant of a supernova that was observed and documented by the Chinese on July 4, 1054 AD and was reportedly visible in the full light of day for 23 days and remained visible at night to the unaided eye for 653 days, according to their records. The subsequent gaseous nebula was first observed by the British amateur astronomer John Bevis in 1731 and added to his sky atlas Uranographia Britannica. It was later observed, independently by the French astronomer Charles Messier in 1758 while searching for Halley’s Comet. He named it M1, the first in his catalog of M-objects that he compiled for the use of comet observers in order that they not confuse these as yet undefined fuzzy objects with a comet. In Messier’s times the science of astronomy was still primarily positional astronomy and the field of astrophysics had not yet taken off so the objects in Messier’s Connoissance des Temps were invariably refered to as nebula and star clusters which future workers would come to understand as a wide variety of deep space objects.
The name “Crab Nebula” for M1 emerged after a drawing made in 1844 by Lord Rosse. The drawing reveals the filamentary structure of the nebula and Roose along with other early astronomers believed they were looking at a faint open cluster of stars that they could not resolve without bigger telescopes. Brighter open star clusters such as the Pleiades (or “Seven Sisters”) served as their example of what the Crab Nebula should look like if only they had bigger telescopes.
By the late 19th century, as the field of spectroscopy emerged, it was realized that the crab nebula was a gaseous entity but M1 was not confirmed to be the actual gaseous remnants of the 1054 supernova until observations made by Walter Baade in 1942 on the 100 inch Hooker Telescope at the Mount Wilson Observatory when he back extrapolated the expansion of the gases to the year 1180 using doppler analysis. That year of origin was later refined to 1140 by later observations The relatively small 86 year disparity between the years 1054 and 1140 are widely interpreted to imply that the gas underwent an early rapid expansion and then slowed down. The proximity of the Crab Nebula in both time and space to the event recorded by the Chinese as the “guest star” are key pieces of evidence cited in supernova theory by astrophysicists and M1 remains an object of great interest in the scientific community.
Further observations of the Crab Nebula by radio astronomers at the Arecibo Observatory 300-meter radio telescope in Puerto Rico reveal a pulsating radio source, a variable star with a period of 33.085 milliseconds. Astrophysicists believe this object to be a neutron star, rotating over 30 times per second. It’s diameter is only 30 kilometers and yet it is as bright as our own sun in the visible spectrum, meaning it is actually 100,000 times more energetic than our sun. This object has a density greater than an atomic nucleus and is interpreted to be the solid remnant of Super Nova 1054.
Main Source: http://www.maa.clell.de/Messier/E/m001.html
