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'It's All Greek to Me': Reading Charts

© Sonya Thomas-Haley

When looking for information on astronomical objects to observe, the beginner is confronted with lots of strange letters and numbers and symbols. If there is anything astronomers love to do, it is categorize. So, it is necessary to learn what some of these symbols and numbers mean.

The stars in a constellation are named with Greek letters in a system first introduced in 1603. In theory, the brightest star should be designated "Alpha," the next brightest "Beta" and so on, but it often doesn't actually end up that way. Regardless, the serious amateur needs to learn the Greek letters. So here is a chart of the alphabet.

You need only take note of the lowercase letters. After astronomers run out of letters, they use a system named after the man who devised it: Flamsteed numbers. These numbers are applied starting at the western border of a constellation and moving east. Still fainter stars are designated by a combination of symbols, letters and numbers from various catalogues, which you will be relieved to learn you can safely ignore unless you're planning on becoming a professional astronomer.

A few prominent stars have common names that many people recognize easily, like Sirius and Betelgeuse (not to be confused with the movie "Beetlejuice." That's not how it's pronounced, anyway. It's properly pronounced "Baytelgoose" though most people don't say it that way. So just pronounce it however you want). Most star names are Arabic in origin. After the collapse of the Roman Empire, it was the Arabs that preserved much of the ancient sky lore and knowledge. Hence, the names have come down to us in the Arabic language.

Let's go over some examples. In the constellation Taurus the Bull, Alpha Tauri is better known by its common name: Aldebaran. That is Arabic for "the follower," as in "the follower of the Pleides." Beta Tauri is also called El Nath, which means "the butting one," since it is the tip of one of the bull's horns. This name has not made its way into common usage, however.

Many stars have such names and it is sometimes entertaining to research these obscure names and their origins. The star 68 Tauri is a double star. For those who want to explore more about stars, their names and the classification systems, go to http://www.astro.uiuc.edu/~kaler/sow/sow...

On a chart, you may see a four-digit number next to an object. This is its designation from the New General Catalogue (abbreviated NGC) which, by the way, is not particularly "new" at all. It's been around for awhile. There is a supplement to it referred to as the Index Catalogue (IC) and its listings are preceeded by the letter "I." The NGC lists galaxies, nebula, open clusters and globular clusters. An example is NGC 1647, which is an open cluster fairly near Aldebaran. It's the little cluster of stars just off to the left in this image.