Alpha Centauri

StarDate: April 14, 2009

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Our region of the Milky Way is in the galactic suburbs. We're a long way from "downtown" -- the galaxy's heart -- and there's a lot of elbow room between neighbors. In fact, the closest star system to our own is more than four light-years away. In other words, if you could travel at lightspeed -- 186,000 miles per second -- it would take more than four years to get there.

The system is Alpha Centauri. It shines as the fourth-brightest star in the night sky. But it's so far south that it's not visible from most of North America, Europe, and Asia, so most of the world's population can't see it.

Alpha Centauri consists of three stars.

Two of them form a tight pair. One of them is a lot like the Sun, while the other is a little smaller and cooler than the Sun; more about that star tomorrow.

The third star is a long way from the others, and it's so faint that it would be barely visible from the others.

Astronomers have searched long and hard for planets around the stars of Alpha Centauri. Since the biggest member of the trio is so much like the Sun, if it does have any planets, conditions around the star should be fairly comfortable for life. What's more, the system is at least a billion years older than our own solar system, so there's been plenty of time for life to have taken hold there. But so far, the searches for planets have turned up empty -- suggesting that there may not be any neighbors around our neighboring stars.

Script by Damond Benningfield, Copyright 2009

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

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