Epsilon Eridani

StarDate: February 4, 2009

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A star that huddles close to the Moon tonight shows us what the Sun will look like in the distant future. Aldebaran, the bright orange "eye" of Taurus, the bull, is nearing the end of its life, so it's puffed up like a giant balloon. The Sun will experience this same fate in several billion years.

But another star in tonight's sky may show us what the Sun was like several billion years in the past.

Epsilon Eridani is in the constellation Eridanus, the river, which curls across the southwest this evening. The star isn't all that bright, but it is visible to the unaided eye.

Epsilon Eridani is only about 10 light-years away, so it's one of our closest neighbors. That makes it fairly easy to study. And in the last decade or so, astronomers have devoted a lot of attention to it.

They've learned that the star is a little cooler, fainter, and less massive than the Sun. There are lots of sunspots on its surface, plus powerful eruptions of gas and energy. This magnetic activity indicates that the star is only about one-fifth the age of the Sun. The Sun probably looked a lot like Epsilon Eridani when it was the same age.

The star is like the Sun in another way: it has an entourage of planets, comets, and asteroids. And one of the planets may come close to the region around the star that's most comfortable for life. Although the planet itself isn't a likely home for life, some of its moons could be. More about that tomorrow.

Script by Damond Benningfield, Copyright 2008

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