So Much More Than Stars!

There's lots in the sky besides the stars, the Sun, the Moon, and the planets. There are also hazy patches of light, looking like distant clouds, called nebulae (nebula is the Latin word for cloud.)

Some of these "hazy patches" can be seen without any optical aid. The Pleiades and Beehive - star clusters - are two. Then there is the Great Nebula in Orion, a cloud of gas over ten light years across, in which stars are being born right now. And finally, the Andromeda Galaxy, our nearest galactic neighbor. The right half of Cassiopeia is like an arrow pointing to it.

In 1758, a French astronomer, Charles Messier, was hunting for comets. It had been predicted that the comet we now call Halley's would reappear late in that year. Annoying Messier were these cloud-like patches in the sky. They looked like comets.

With his primitive telescope, though, he had no idea what these hazy patches were. He called them all nebula. Now they're called deep sky objects.

Day after day, though, these patches stayed in the same position (relative to the stars,) so he knew they couldnąt be the comet he was seeking. He compiled a list of these patches so they wouldn't mislead him, or anyone else engaged in the serious work of comet hunting. And thus was born the famous Messier list.

There are many different kinds of these objects: there are star clusters, like the Beehive. There are clouds of hydrogen gas, like the Orion nebula, a birthplace of stars. And there are the galaxies.

The Pleiades are number 45 on his list, or M45; the Beehive, M44. The Orion Nebula, M42; the Andromeda " nebula," M31.

The hazy patch that started the list in the first place is the Crab Nebula in Taurus, which is M1. Though it can only be seen with a telescope, it looks like its name: a hazy crab-shaped patch. It is a supernova remnant, the remains of a star that exploded over a thousand years ago.

By the way, what about the comet Messier was hunting? He found it in early 1759, but he was not the first to see it then. What is most famous about him is the list he made.

(01/11/06)