Published on Jan 11, 2020

Nebula Background Images

License Info: Creative Commons 4.0 BY-NC

In 1054, Chinese astronomers stared up at the night sky in wonder, as they observed a new and mysterious object dancing in the Universe. This strange celestial object, that heralded the explosive “death” of a massive star, told the sad tale of how once there was a star that is now gone. Nevertheless, this stellar grand finale left behind a sparkling relic of the now-dead star’s former existence–a shimmering, glimmering, multicolored object that is now known as the Crab Nebula. The Crab Nebula was the first astronomical object to be identified with a historical supernova–the brilliant and fatal explosion of a doomed star. In March 2018, astronomers released a new and beautiful composite image of the Crab Nebula, using the Chandra, Hubble, and Spitzer space telescopes–showing how the Crab lights up the Universe in three different, dazzling wavelengths of the electromagnetic spectrum.

The Crab Nebula (catalogue designations M1, NGC 1952, and Taurus A) is located in the constellation Taurus (the “Bull”), and it received its current name from the Anglo-Irish astronomer William Parsons (1800-1867), who observed the object in 1840, using a 36-inch telescope. Parsons also made a sketch of this distant nebula that resembled a crab.

The Crab Nebula has an apparent magnitude of 8.4, which is similar to that of Saturn’s large hydrocarbon-slashed moon, Titan. As such, the nebula is not visible to the unaided human eye but it can be seen with the help of binoculars when conditions are favorable. The Crab is situated in the Perseus Arm of our Milky Way Galaxy, at a distance of about 6,500 light-years from Earth. It has a diameter of about 11 light-years, and is expanding at a rate of about 930 miles per second–or 0.5% of the speed of light.


At the heart of the Crab Nebula lurks the Crab Pulsar, a wildly whirling young neutron star that is approximately 17-19 miles across, with a breathtaking spin rate of 30.2 times per second. The Crab Pulsar manufactures pulses of radiation from gamma rays to radio waves. At X-ray and gamma-ray energies over 30 keV, the Crab Nebula is usually the most brilliant persistent source in the sky.

There are many reasons why the Crab Nebula is one of the most well-studied celestial objects. For example, it is one of only a small number of objects where there is strong historical evidence indicating when a doomed star blasted itself to pieces in a supernova tantrum. Having this definitive timeline is a valuable tool for astronomers to use in their quest to understand details of the explosion–as well as its dazzling aftermath.

In the case of the Crab, observers in several countries reported the appearance of what they called a “new star” in 1054 A.D. A great deal of information has since been provided to astronomers, courtesy of the Crab, following its stunning initial appearance in the sky. Currently, astronomers understand that the Crab Nebula is powered by the Crab Pulsar–a highly magnetized, rapidly spinning neutron star that was born like a Phoenix rising from the funeral pyre of its progenitor massive star. The progenitor star perished explosively after it had depleted its necessary supply of nuclear-fusing fuel and collapsed. The stellar mix of a strong magnetic field with rapid rotation in the Crab produces a powerful electromagnetic field that is responsible for creating jets of matter and anti-matter that rush screaming away from both the north and south poles of the pulsar, as well as a ferocious wind that shrieks out in the equatorial direction.

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