Two bright orange stars stare down from high in the south this evening. Aldebaran is at one point of a V-shaped pattern of stars that outlines the face of Taurus, the bull. And Betelgeuse, to its southeast, is at the top left corner of a rectangle that outlines Orion, the hunter.
The stars look orange because their surfaces are quite cool -- thousands of degrees cooler than the Sun. And both stars are gigantic. Aldebaran is several dozen times wider than the Sun, while Betelgeuse is several hundred times wider.
Another colorful giant lines up below the feet of Orion. It's known as Hind's Crimson Star. It's comparable in size to Betelgeuse -- big enough to swallow the entire inner region of the solar system if it were to take the Sun's place.
As the name suggests, Hind's Crimson Star is one of the reddest stars in the sky. It's visible through binoculars or a small telescope, and its color stands out.
It looks so red for a couple of reasons. First, it's even cooler than Aldebaran and Betelgeuse. And for another, it's dredged up a lot of carbon from deep within its interior. The carbon absorbs bluer wavelengths of light and lets the red shine through.
The star blows a lot of the carbon into space, where it encircles the star in a large shell. Over time, the shell may vary in thickness, causing the star to appear brighter or fainter. And the shell contributes to its deep red color -- the color of a bright, cool giant.
Script by Damond Benningfield, Copyright 2008
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