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HD 69830

February 21, 2010

It's not exactly just like home, but a system of planets orbiting a nearby star is more like our own solar system than any other yet discovered. It has three big-but-not-too-big planets, plus a dense asteroid belt.

The star is HD 69830. It's about 40 light-years away, in the constellation Puppis. It sails quite low across the south on winter evenings, not far from Sirius, the brightest star in the night sky.

HD 69830 is a lot like the Sun -- it has about the same size, mass, and temperature. Sun-like stars are prime targets in the search for life because conditions are most like those in our own solar system.

Two of the planets that orbit HD 69830 are so close to the star that they're too hot for life. But the third is inside the star's habitable zone -- the region where temperatures are just right for liquid water.

The planet itself probably isn't a good candidate for life, though. It's much more massive than Earth, so it probably has a big, rocky core surrounded by thick layers of liquids and gases -- but no solid surface. But any moons that orbit the planet might be better environments for life.

The moons might have to survive a regular bombardment by giant space rocks, though, because the asteroid belt is not too far away. It contains far more material than our own asteroid belt, so it probably pummels the planets and their moons with giant space rocks -- collisions that would make these worlds anything but homey.

Script by Damond Benningfield, Copyright 2009

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