20 light years from Earth slumbers the red dwarf star Gliese 581.  Today a team of astronomers announced an astonishing discovery-- the star has a planet which is potentially habitable by humanity.

Over 200 so-called "exoplanets" -- planets outside our own solar system -- have already been found.  But so far, all of them have suffered from the "goldilocks problem," either too hot, too cold, or far too massive to support life.

But the new planet, which so far is only being called "c," is different.  It has an atmosphere, liquid water, a surface temperature estimated to range from 32 to 104 degrees Fahrenheit.  It is roughly five times as massive as the earth but, due to a larger diameter, has a surface gravity only1.6 times that the Earth's.   It's also much closer to its parent star, having a 'year' only 13 days long.  The view from the surface would be spectacular, with the planet's sun appearing in the sky some 20 times larger than does our moon.

"On the treasure map of the Universe, one would be tempted to mark this planet with an X", says report co-author Xavier Delfosse of Grenoble University. "Liquid water is critical to life as we know it.  Because of its temperature and relative proximity, this planet will most probably be a very important target of future space missions dedicated to the search for extraterrestrial life."

The team examined 100 different stars using the HARPS planet searcher at the European Southern Observatory in the Chilean Alps.