Aquarian Planet
 A giant, ringed planet orbits a red-dwarf star in this artist's concept. Red dwarfs are the smallest and coolest of all "normal" stars. Yet they also live for many billions of years, so they could provide stable environments for the development of life. Planets like this one are unlikely to harbor life, although their moons might be more hospitable. [NASA/ESA/G.Bacon (STScI)]
One of the wonders of Aquarius is not far from the Moon's position tonight -- an obscure star system known as Gliese 876.
The star itself is a pipsqueak. It's classified as a red dwarf -- the smallest, faintest class of stars. Gliese 876 is only a third as massive as the Sun, and looks about a thousandth as bright. So even though it's only 15 light-years away, it's far too faint to see without a telescope.
The system contains at least three planets -- including one that may be one of the most Earth-like planets yet discovered. From a tiny "wobble" in the star's light caused by the planet's gravitational pull, along with other evidence, astronomers calculate that the planet is probably about twice as big as Earth, and a few times more massive. Like Earth, it's probably a rocky world. And its gravity is strong enough to retain any atmosphere it was born with.
The planet isn't a likely home for life, though. It's so close to Gliese 876 that surface temperatures are hundreds of degrees. So if anything lives on the planet, it would have to be pretty different from life on Earth.
Just a decade or two ago, most scientists would have said that no red-dwarf would be likely to sustain life. But it seems these stars might not be so inhospitable after all. More about that tomorrow.
Script by Damond Benningfield, Copyright 2007
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