There's a New Earth-Size Planet in the Neighborhood (Galactically Speaking)

The yeoman work of NASA's Kepler Space Telescope has revealed our Milky Way galaxy to be lousy with planets - surely tens of billions of them, if you extrapolate from what Kepler has detected so far in a small patch of the sky.

Astronomers with ground-based telescopes are taking a broader view of the heavens - they're looking all over the sky at nearby stars, searching for the low-hanging fruit of planets that are relatively close. A new study published Wednesday in the journal Nature tells of a rocky planet, roughly the size of the Earth, that is just 39 light-years away - practically within shouting distance in the galactic scheme of things.

It is not the closest rocky planet to our solar system - there are two others that are more proximate - but of the nearby rocky planets, it is closest to the Earth in size.

Named GJ 1132b, the planet was discovered with an array of six telescopes on three different mountains in Chile. It's not habitable. The surface is scorched by the parent star - an old, red dwarf that is about 5 billion years old. The planet, with a diameter approximately 1.2 times that of Earth's, might have an atmosphere. Astronomers will look closely at the parent star to see how the planet, as it crosses the face of the star as seen from Earth, alters the starlight. Essentially they will be studying the planet's sunsets. That would tell the astronomers about the atmosphere, if there is one.

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"It was very hard to find, and just barely at the limit of our detection, but it gives us finally a chance to really study a rocky planet around another star in an unprecedented level of detail," said MIT astronomer Zachory Berta-Thompson, the lead author of the new paper.

There are about 10 times as many red dwarf stars in our galaxy as there are sunlike stars, he said. Whether planets orbiting red dwarfs are congenial to life is a matter of debate. Berta-Thompson said that he hopes further study of this new planet will help resolve whether such planets can hold onto their atmospheres and be potentially habitable. His team wants to look at it with the Hubble Space Telescope, or perhaps in a few years with NASA's James Webb Space Telescope, which has a 2018 launch date.

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Meanwhile, in other space news, the larger of Mars' two moons is on the verge of disintegrating. Phobos has about 30 million years left, judging by the grooves on the surface, according to a NASA news release based on research at the agency's Goddard Space Flight Center.

Phobos is in a very low orbit, less than 4,000 miles above the surface, and the gravity of Mars will eventually rip it apart. But Phobos needs to keep itself in one piece for a little while: NASA is noodling the idea of a human mission to Mars in a couple of decades that would actually be a mission to Phobos.

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It would be relatively easy to land on the moon and use it as an operating base for real-time control of robotic instruments on the Martian surface. Engineering challenges abound when trying to put a large payload safely through the thin Martian atmosphere and onto Martian soil. Parking on Phobos would be much easier.

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VIDEO: Scientists have discovered a new exoplanet that is located 39 light-years from Earth, making it the closest Earth-sized exoplanet yet discovered.

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