In 1884, Lord Rosse published a first sketch of M1, and gave the name ‘Crab Nebula’ because it look a bit like a scorpion or a crab.
John Duncan found in 1921 that the nebula is expanding. In 1949, the radio astronomers Boltoin, Stanley and Slee identified the Crab Nebula as a radio source, making it the first non-solar system radio to be identified with a known optical object.
The detection of the Crab Pulsar at the centre of the Crab Nebula gave final confirmation to the theory that the core of a gravitational collapsing star settles down to the equilibrium state of a neutron star, if it is mass is inferior to the relevant Chandrasekhar limit.
Discovery of Crab Nebula