The closest single star out there is just 4.2 light-years away. But don't bother looking for it. It's so faint that you can't see it with your eyes alone. In fact, it's not very impressive even through a telescope.
Proxima Centauri shines so feebly because it's a red dwarf -- a small, faint class of stars. It's just one fifth as massive as the Sun, and not much bigger than the planet Jupiter. And it emits less visible light in a year than the Sun produces in just half an hour.
Because it's much cooler than the Sun, though, Proxima Centauri produces a lot more infrared energy than visible light. When you add them together, the star's output is a little more impressive -- as much energy in a year as the Sun produces in about a day.
Astronomers have searched the star for evidence of planetary companions, but so far they haven't found any. And even if the search does find a planet, it's not likely to be a safe haven for life.
That's because Proxima Centauri frequently produces powerful outbursts of X-rays and charged particles. Since the star is so cool and faint, a planet would have to be quite close to be warm enough to support life like that on Earth. But at such close range, it would get blasted by deadly radiation. So a planet would need a thick atmosphere and a strong magnetic field to protect life -- or life would have to evolve in such a way that it wasn't bothered by the fireworks from our faint but active neighor.
Script by Damond Benningfield, Copyright 2009
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