Every year, more and more exoplanets are discovered. The latest one to join the list is designated GJ 1132b and sits about 39 light-years away from Earth. Mark Watney won’t be getting stranded on it anytime soon, but it’s close enough for detailed study by the Hubble Space Telescope and future telescopes.

“This planet is going to be a favorite target of astronomers for years to come,” says lead author Zachory Berta-Thompson from MIT. What’s so special about it?

GJ 1132b sits orbits a red dwarf star only about 20% the size of our Sun. And it orbits very close. Each orbit takes 1.6 days at a distance of 1.4 million miles. Mercury, the Sun’s closest neighbor, orbits at 36 million miles. Despite a smaller star, the closer orbit means this exoplanet is hot. Temperatures reach about 450 degrees Fahrenheit. Way too hot for water, but cool enough for something else. An atmosphere.

“Our ultimate goal is to find a twin Earth, but along the way we’ve found a twin Venus,” says astronomer David Charbonneau of the Harvard-Smithsonian Center for Astrophysics (CfA). “We suspect it will have a Venus-like atmosphere too, and if it does we can’t wait to get a whiff.”

GJ 1132b is the coolest confirmed rocky exoplanet yet discovered. Other exoplanets orbit much larger stars and can see temperatures soar to a blazing 2,000 degrees Fahrenheit or higher.

Because of this exoplanet’s close (relatively) proximity to Earth, scientists believe telescopes like the Hubble and future telescopes should be able to study its atmosphere. If it exists. The team behind the discovery is requesting follow-up observations by the Hubble and Spitzer space telescopes.

You can see how much closer this exoplanet is compared to most others in the animation below. The vast majority of exoplanets are found more than 1,000 light years away from Earth.

What’s GJ 1132b like?

Besides the searing temperatures, GJ 1132b is similar to Earth in size. It’s 16% larger than Earth, and its diameter is about 9,200 miles. It has 60% more mass than Earth which indicates a rocky composition. Trying to shed a few pounds? You wouldn’t want to step on the scales on GJ 1132b. You would weigh about 20% more on GJ 1132b than on Earth.

Spotting exoplanets with the MEarth-South array

You don’t need huge telescopes to find distant planets. The Harvard-Smithsonian Center for Astrophysics (CfA) uses two MEarth arrays to watch the closest M dwarf stars for signs of transits (when a planet passes between us and its host star affecting the star’s brightness). The MEarth North array sits on Mount Hopkins just south of Tucson, Arizona. MEarth South sits on Cerro Tololo in Chile.

MEarth South array

The MEarth South array began searching the night’s sky early last year. Eight 40cm telescopes are controlled remotely in Cambridge, MA as they keep tabs on the closest M dwarf stars.


While GJ 1132b doesn’t sit in the Goldilocks Zone, being able to study an atmosphere light-years away would still be huge. If the Hubble or Spitzer can’t get a good look at it, we’ll have to wait for the James Webb Space Telescope (JWST). Right now, the JWST is scheduled for launch in October 2018.


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