Charles Messier had his eye on a comet. It was August 28th of 1758, and Messier was scanning between the horns of Taurus, the bull. He later recalled finding "a whitish light, elongated in the form of the light of a candle, which didn't contain any star."
While the comet has faded to obscurity, the other little light -- known today as the Crab Nebula, because its outline resembles the shape of a crab -- became the anchor of one of the most famous volumes in astronomy history: Messier's "Catalogue of Nebulae and Star Clusters."
In Messier's time, hunting comets was a leading astronomical activity. But Messier and others kept coming across little smudges and whirls of light that resembled comets.
So to make comet hunting more productive, Messier compiled a catalog of about a hundred of these in-the-way objects, which are star clusters, galaxies, and clouds of gas and dust.
The Crab Nebula became the first entry in Messier's catalog -- M1. It's the expanding cloud of debris from a star that blew itself apart. It's a good laboratory for studying exploding stars and the way they "seed" the universe with chemical elements. So today, the Crab Nebula is no longer considered a nuisance -- it's a treasure.
The Crab is visible through small telescopes, near the tip of Taurus's southern horn. It rises in the wee hours of the morning, well below the bull's orange "eye," the star Aldebaran.
More about the Crab tomorrow.
Script by Damond Benningfield, Copyright 2008
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