View your list of saved words. (You can log in using Facebook.)
Bright nebula in the constellation Taurus, about 5,000 light-years from Earth. Roughly 12 light-years in diameter, it is the remnant of a supernova, first observed by Chinese and other astronomers in 1054, that was visible in daylight for 23 days and at night for almost two years. Identified as a nebula c. 1731, it was named (for its form) in the mid-19th century. In 1921 it was discovered to be still expanding; the present rate is about 700 mi/second (1,100 km/second). The Crab is one of the few astronomical objects from which electromagnetic radiation has been detected over the entire measurable spectrum. In the late 1960s a pulsar, thought to be the collapsed remnant star of the supernova, was found near its centre.
This entry comes from Encyclopædia Britannica Concise. For the full entry on Crab Nebula, visit Britannica.com.
Seen & Heard
What made you look up Crab Nebula? Please tell us what you were reading, watching or discussing that led you here.