Crab Nebula (M1 / NGC 1952)
- Type: Supernova Remnant
- Distance: Approximately 6,500 light years from Earth
- Size: About 11 light years in diameter
- Apparent size: 7.0 x 4.0 arc minutes
- Apparent magnitude: 8.4
- Age: Around 960 years
- Constellation: Taurus
The Crab Nebula is what remains of a star that exploded in a supernova around a century ago. The supernova was documented in 1054. It resides around 6500 light years from Earth in the constellation Taurus.
The supernova left behind a pulsar, which is a highly magnetized rotating neutron star. A neutron star is the collapsed core of a massive supergiant star. Neutron stars are the smallest and densest stellar objects. The radiation from a pulsar can be observed only when one of the rotating poles is pointed at Earth, similar to the effect of a lighthouse.
Surrounding the Crab Nebula is a pulsar wind nebula, which is caused by stellar winds generated by the pulsar. Interestingly, the Crab Nebula is one of the few astronomical objects in which we can observe change within the span of just a few years.
In a supernova, the size of the star dictates what is left of the core after the explosion. Smaller stars leave behind a long-lived white dwarf. Massive supergiants leave behind a neutron star, and when the poles of a neutron star are pointed at Earth those neutron stars are called pulsars. The largest stars collapse into a black hole. Black holes share many characteristics with stars and could well be described as a star that is dense enough with strong enough gravity to keep light from escaping.
All organic matter that contains carbon was originally produced in stars. To quote Carl Sagan, "We're made of star stuff." Most of the elements in our bodies were made in a star and reached Earth by way of supernova. Many elements have likely been through multiple supernovae before reaching Earth.
We are all connected by the stars, in more ways than we likely realize.
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