An artist's rendering of GJ 1132b, the closest Earth-sized rocky exoplanet yet discovered. Photo by MIT/Dana Berry
BOSTON, Nov. 12 (UPI) -- Astronomers have found a rocky exoplanet orbiting a star just 39 light years away. GJ 1132b is the closest Earth-like world yet found by scientists. For context, the Milky Way galaxy stretches some 100,000 light years across.
By measuring the amount of its host star's light the exoplanet blocks, researchers determined that GJ 1132b is 1.2 times the size of Earth. The wobble of its red dwarf host, GJ 1132, suggests the planet's mass is 1.6 times the mass of Earth. A planet of such proportions is likely composed of rock, researchers say.
Scientists detailed the planet's Earth-like attributes in a new paper, published this week in the journal Nature.
But beyond size, mass and composition, GJ 1132b and Earth have little else in common. Unlike Earth, which spins, the exoplanet is tidally locked, meaning the same half of the sphere faces its sun at all times -- leaving one half permanently in the darkness.
Given its proximity to its host star, the exoplanet is also unbearably hot, upwards of 500 degrees Fahrenheit -- far too hot for water to exist on its surface.
"The temperature of the planet is about as hot as your oven will go, so it's like burnt-cookie hot," Zachory Berta-Thompson, a postdoc in MIT's Kavli Institute for Astrophysics and Space Research, said in a press release. "It's too hot to be habitable -- there's no way there's liquid water on the surface. But it is a lot cooler than the other rocky planets that we know of."
Scientists believe it's just cool enough to host a substantial atmosphere. And it's close enough to study in greater detail.
Berta-Thompson is excited to find out what color the exoplanet's atmosphere, as well as its chemical composition and wind patterns -- all observations Hubble's successor, the James Webb Space Telescope, which launches in 2018, will likely be able to make.
"We think it's the first opportunity we have to point our telescopes at a rocky exoplanet and get that kind of detail, to be able to measure the color of its sunset, or the speed of its winds, and really learn how rocky planets work out there in the universe," Berta-Thompson said. "Those will be exciting observations to make."
By understanding the different types of atmospheres rocky planets are capable of holding onto, astronomers will ultimately be able to more accurately target those capable of hosting life.
