Some 22 light years away, a short hop by galactic standards, six planets, and maybe a seventh, orbit the star Gliese 667C. Three of these planets orbit within the star’s narrow habitable zone, or “Goldilocks Zone,” where the temperature is just right for liquid water to exist at the surface. These three planets take up all of of the potential orbits within Gliese 667C’s habitable zone, making the Gliese 667 system one of the nearest and most life-friendly solar systems on the books.
Last year, astronomer Philip Gregory surmised that the star Gliese 667C had three life-amenable planets, but other scientists argued that his proposed orbits for the planets weren’t physically possible. Today, though, the European Southern Observatory, describing a new study, says that the star does have three habitable planets after all (though they’re still not where Gregory said they’d be.)
The Gliese 667 system is an interesting one. The six planets are orbiting a a small red dwarf star, Gliese 667C. This little star, in turn, is orbiting two bigger stars, Gliese 667A and Gliese 667B. These two bigger stars are, in turn, orbiting a shared center of mass as a binary star. From the surface of one of these potentially habitable planets around Gliese 667C, then, says the ESO, “the two other suns would look like a pair of very bright stars visible in the daytime and at night they would provide as much illumination as the full Moon.”
Of all the known potentially habitable planets outside the solar system only one other, Gliese 581 g, is closer to Earth.
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