Planet 39 light years away may permit atmosphere study

Venus-like GJ 1132b is closest Earth-sized planet yet discovered beyond the Sun

A Venus-like rocky planet 39 light years from Earth could provide astronomers with an early opportunity to study the atmosphere of a world outside our solar system.

GJ 1132b is the closest Earth-sized planet yet discovered beyond the Sun.

Scientists have determined that its surface is likely to be a roasting 260C. The scorching temperatures mean liquid water and life as we know cannot exist on GJ 1132, but the planet could still have a substantial atmosphere.

Because it is so close, the air and clouds above GJ 1132b could be studied in detail using space and ground-based telescopes.


‘Ultimate goal’

Astronomer Dr David Charbonneau, from the Harvard-Smithsonian Center for Astrophysics in the US, said: "Our ultimate goal is to find a twin Earth, but along the way we've found a twin Venus.

“We suspect it will have a Venus-like atmosphere too, and if it does we can’t wait to get a whiff.”

Unlike Venus, GJ 1132b always has the same face pointed at its host star, a small red dwarf. It hugs its star closely at a distance of just 1.4 million miles - far closer than the nearest planet to the Sun, Mercury.

Scientists have calculated that the planet is roughly 1.2 times the size of the Earth, with about 1.6 times its mass.

‘Burnt-cookie hot’

Co-author Dr Zachory Berta-Thompson, from the Massachusetts Institute of Technology's Kavli Institute in the US, said: "The temperature of the planet is about as hot as your oven will go, so it's like burnt-cookie hot. 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.

“The planet is cool enough that it can retain an atmosphere.”

A description of GJ 1132 appears in the latest edition of the journal Nature.

The James Webb Space Telescope (JWST), the larger successor to the Hubble Space Telescope due to launch in 2018, could be used to identify the chemical make-up of the planet's atmosphere and get a glimpse of its weather, say the scientists.

“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 colour of its sunset, or the speed of its winds, and really learn how rocky planets work out there in the universe,” said Dr Berta-Thompson.

Ultimately astronomers hope to detect signs of life in the atmospheres of exoplanets.

Press Association