More Epsilon Aurigae

StarDate: August 4, 2009

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The eastern pre-dawn sky is offering up an impressive array of stars and planets right now. Venus is the most obvious -- it's the "morning star." The constellation Orion is to its right, orange Mars is to its upper right, and Capella, the brightest star of Auriga, the charioteer, is to its upper left.

But many astronomers are paying more attention to a fainter light in that region of the sky -- a star that's about to start fading away.

The star is Epsilon Aurigae, which is just to the right of Capella. It's actually a binary system -- a supergiant star, and a dark, pancake-shaped cloud of dust.

Every couple of decades, the disk passes directly in front of the star, blocking some of the star's light.

The last of these eclipses took place in the mid-80s. But today, astronomers have a far more impressive arsenal to watch with.

With these instruments, astronomers hope to clear up some mysteries. They suspect, for example, that there's a small star at the center of the disk. Without a star's gravity to hold it together, the disk would quickly dissipate. But no one's ever seen a star there.

The eclipse is expected to begin as early as this week, when the fringes of the disk begin to pass in front of the star. But the thickest part of the disk won't arrive until December. For about a year after that, Epsilon Aurigae will shine just half as bright as it does now. And it won't fully recover its luster until May of 2011.

We have a chart showing you the star's location on our website -- stardate.org.

Script by Damond Benningfield, Copyright 2009

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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