Studying the stars in optical light alone -- the light that's visible to the human eye -- is a bit like trying to appreciate a symphony when you can hear only one instrument. It might be pretty, but it doesn't tell the whole story.
Until the Space Age, though, that's the limitation that astronomers faced -- they couldn't appreciate the entire spectrum of energy. And that means they missed a lot of important details about the universe.
An example is Fomalhaut, the brightest star of Piscis Austrinus, the southern fish. It's low in the southeast at nightfall. It's easy to pick out because it's the only bright star in that region of the sky.
From visible light alone, astronomers could tell that the star is about 25 light-years away, and that it's a little bigger, hotter, and more massive than the Sun.
But one of the most interesting discoveries about Fomalhaut came 25 years ago. An orbiting satellite measured the infrared energy from the star. Earth's atmosphere blocks most of the infrared, so it's best studied from space.
The satellite detected an infrared glow around the star. The glow is produced by grains of ice and dust in a big disk around Fomalhaut. The disk is probably similar to the one that gave birth to the planets of our own solar system.
Later satellites saw big gaps in the disk. The gaps could be swept clean by orbiting planets.
So adding the infrared has helped astronomers piece together the symphony of a nearby star.
Script by Damond Benningfield, Copyright 2008
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