Week of March 7 -- 13, 2010 by Dennis Mammana on Creators.com

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Week of March 7 -- 13, 2010

One thing I've learned from helping beginning stargazers is that they often have some deeply ingrained misconceptions. One of the most common is this: "If you've seen one star, you've seen 'em all."

Experienced sky watchers, however, know that no two stars are exactly alike. Each can display its own personality in a number of ways, but often the most visible is a star's color.

Most people don't notice this immediately because the human eye is not capable of perceiving color well under low-light conditions. We know this to be true if we've ever looked around a relatively dark room; shapes and shades of gray are pretty easy to spot, but colors are virtually nonexistent. Turn the lights on, however, and we find that we're surrounded by vibrant colors.

When gazing skyward, we discover that star colors are quite subtle. Binoculars or telescopes capture much more light than the human eye and make these a bit more obvious. So if we'd like to see star colors with the naked eye, we need to look toward the brightest of stars.

The best place to start is within the constellation of Orion, the hunter. At this time of year, Orion stands majestically midway up in the southern sky after dark.

Its large vertical rectangle of four bright stars forms the hunter's shoulders and knees; at its center lie three stars that form a nearly straight line — the belt of the great hunter.

The bright star marking the northeastern corner (the shoulder) of Orion is known as Betelgeuse. This red supergiant star glows with an orange light that is pretty tough to miss. At the opposite corner (in the hunter's knee) lies sparkling Rigel, a supergiant that displays a slightly bluish-white color.

Star colors are more than just a curiosity; they tell us something about stellar temperatures. While our sun glows with a surface temperature of around 10,000 degrees Fahrenheit, reddish-orange stars like Betelgeuse are relatively cool (6,300 F) and can often live much longer than the sun. Bluish-white stars like Rigel, on the other hand, are tremendously hot (18,000 F); they can burn this furiously for only a relatively short time and, therefore, must be much younger than the sun.

After you've spotted these two fine examples of stellar color, check out some of the other bright stars around the sky to see what you can learn about their relative temperatures and ages.

To find out more about Dennis Mammana and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.