Nov. 11, 2015

A newfound alien world orbiting a small, nearby star could be one of the first exoplanets scientists get to investigate in detail.

THERE ARE NEARLY 2,000 EXOPLANETS on the books, and much is known about them, at least in broad strokes, such as their size, mass and distance. Yet the details that give these celestial bodies their individuality—such as weather, winds, air, and even the colors of their skies—remain scant. This is particularly true for the growing number of small, Earth-size exoplanets, from which astronomers hope to glean clues about life's potential genesis elsewhere in the universe.

Now a newfound exoplanet announced today in the journal Nature, and discovered by a member of the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology, offers scientists one of the best chances to truly know an extraterrestrial planet. Called GJ 1132b, it crosses the face of a nearby red dwarf star only 40 light-years away. These so-called transits—mini-eclipses, really—have allowed researchers to gauge GJ 1132b's size as just 1.2 times that of Earth's. Other measurements have revealed it boasts a similar density to our rocky planet. All told, GJ 1132b is the closest transiting, Earth-size, rocky planet ever spotted.

GJ 1132b is too hot for life because of its tight orbit, but its relatively large size compared to its star nevertheless makes it an ideal planetary laboratory. It will likely be one of the first targets of the James Webb Space Telescope, Hubble's successor, launching in 2018. The Webb will gather starlight streaming through the planet's atmosphere, bearing markers of its composition. GJ 1132b might thereby serve as a Rosetta Stone for future characterizations of small exoplanets.
On October 28, 2015, The Kavli Foundation spoke with three astrophysicists about why the discovery of GJ 1132b could be crucial to the quest to understand worlds in other solar systems.

Image: An artist's impression of an exoplanet transiting a red dwarf star in the same way as the newfound, Earth-size exoplanet, GJ 1132b.