The comet ferret
Published on Jan 21, 2006 at 7:38 pm.
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Filed under Uncategorized, astronomers.
Hmm. I can’t think about what to blog about. I suppose that I could blog about my new waffle maker, but that seems silly. So, I decided to do something simple for those of y’all who don’t know the terminology of astronomy. That is actually one of the tougher things for my students at first: the jargon. Astronomy is one of the most ancient sciences, we have developed our own language to describe things. The first week or two we are just covering new terms that the students need to know.
You may have heard astronomers using letters and numbers to refer to certain astronomical objects. For example, there is a massive cluster of stars in the constellation Hercules called M 13. M 13 is a roughly spherical mass of perhaps a hundred thousand stars orbiting around the rest of our galaxy. It is about 25,000 lightlyears away. So, why call it M 13? Why not some other name?
M 13 isn’t the only one of these objects. The great nebula in Orion is called M 42, and the Andromeda Galaxy is also known as M 31. So, what is all this M stuff about?Â
It goes back to a fellow named Charles Messier. Born in France in 1730, he became interested in astronomy at age 14 when a rather bright and impressive comet was visible. He became an astronomer and began working at an observatory. Halley’s Comet was to return, as it does every 76 years, when Messier was about 29 years old. He set out to be the first person to find it as it came by that time. Unfortunately, someone else found it first, but Messier was hooked on hunting for comets. That became his life’s work. In face, he found so many comets that he was nicknamed the “ferret of comets.â€Â Whenever I think of calling someone a ferret, the character of Major Burns from the TV show M*A*S*H comes to mind. Hawkeye was always calling him “ferret face.â€Â Well, I guess if you are going to be called a ferret, then being a ferret of comets isn’t so bad.
However, in Messier’s search for comets, he found many other objects in the sky. You see, most comets don’t look like the bright head with a long tail. Even those that do look like that start off as tiny little fuzz balls in the sky. Many never look like anything more than fuzz balls. So, Messier started to make a list of the fuzzy things that were not comets. That way, whenever he found a fuzzy thing, he could look at the list to see if it were already there. Other astronomers hunted for comets, too, and so Messier published his catalog of non-cometary objects.  Most of these objects he found himself, though a few were found by others. In the telescopes of the day, many objects that are clearly groups of stars could be mistaken as fuzzy things, so objects such as the Pleiades are on the list (the Pleiades are M 45, short for Messier number 45).Â
Though Messier’s life work was comets, he is most well known for his catalog of non-comets. Many of the brighter and more spectacular celestial objects are in his catalog, and they are known by their entry number in Messier’s catalog. For example, the Andromeda Galaxy is entry number 31, so it is M 31. The Crab Nebula is the first object in the catalog, so it is M 1.Â
Later, William Herschel produced the General Catalog of non-stellar objects. Then, in the late 19th Century, J. L. E. Dreyer published the New General Catalog. Objects in this catalog are identified by the prefix NGC. So, for example, another globular cluster, one the farthest ones from us, is called NGC 7006.Â
So, that is what we mean by these letters and numbers when we talk about galaxies, nebulae, etc. So, since I am having trouble thinking of what to write about, do any of you have any suggestions?
-Astroprof
