Strands of gas and dust form the spectacular Crab Nebula, the remnant of a star that exploded almost a millennium ago as seen from Earth. The explosion acted as a chemical factory, creating many elements that were then expelled to space; they form different colored strands in this Hubble Space Telescope image. The nebula, also known as M1, spans about a dozen light-years in the constellation Taurus. [NASA/ESA/J. Hester/A. Loll (ASU)]
You are here
A colorful crab scuttles across the sky on December nights. It’s faint and far away. But almost a thousand years ago, it announced its birth in dramatic fashion — as a brilliant new star in the constellation Taurus. It was bright enough to see in daylight for several weeks.
The Crab Nebula is a cloud of glowing gas that spans about a dozen light-years. It’s called the crab because its tendrils of gas resemble a crab.
The nebula was born when a heavy star exploded as a supernova, blasting its outer layers into space. The gas is racing outward at millions of miles per hour, so it’s spread out to form a big cloud.
At the center of the nebula is the star’s crushed core — a neutron star. It’s roughly twice as massive as the Sun, but only about as wide as a small city. At such extreme density, a teaspoon of its matter would weigh as much as 10 million African elephants.
The explosion that created the nebula also caused the neutron star to spin more than 30 times a second. And it created a magnetic field a trillion times stronger than Earth’s. As the star spins, the magnetic field causes it to beam energy into space. [audio: pulsar] Radio telescopes detect this beam as “pulses” of energy, so the neutron star is also known as a pulsar.
Taurus is low in the east at nightfall and climbs high across the south later on. The nebula is in its southern horn, and is visible through a small telescope — the glowing remains of an exploded star.
Script by Damond Benningfield, Copyright 2015