Pisces, the fish, is one of the faintest constellations of the zodiac -- but it has one of the reddest stars in the sky. The star is bright enough to see with just the unaided eye, if you get away from city lights.
TX Piscium is a red giant -- a star that's much larger and brighter than the Sun.
Its ruby glow has two causes. First, like all red giants, TX Piscium is cooler than the Sun, and cool stars look reddish. And second, nuclear reactions inside TX Piscium have created a lot of carbon, and carbon compounds in the star's outer layers block most of its blue light, deepening the red color. In fact, astronomers call TX Piscium not just a red giant but also a carbon star. You can thank that carbon for the beautiful hue.
You can also thank carbon for your own existence. Human life is based on carbon, and most of the carbon on Earth was manufactured in stars like TX Piscium. When these stars cast their outer layers into space, the newly minted element enriched the clouds of gas and dust that gave birth to new stars and planets -- including the Sun and Earth.
TX Piscium is in western Pisces, south of the square of Pegasus. Although it's visible to the unaided eye, the star is so faint that you'll probably need a starchart to find it. Through binoculars, TX Piscium looks especially red. Its beauty signifies the presence of carbon -- and reminds us that we are all children of the stars.
Tomorrow: children of a comet.
Script by Ken Croswell, Copyright 2009
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