This Earth-like exoplanet seems to have an atmosphere

Finding Earth-like planets that could theoretically support life has become something of a hobby for space researchers. In the last couple of years, we found possibilities in Proxima-b, Kepler-452b and a further seven all orbiting one star. So I’d understand if you’re a little bit jaded when I say that researchers have found yet another, but there’s one key difference: scientists have detected an atmosphere around this one – a little planet called Gliese 1132b, tucked away in the Vela constellation.

That’s important, because this is the first time an atmosphere has been detected around a planet of a size and mass similar to Earth. That means there’s a chance that life as we know it exists. Or as lead researcher John Southworth of Keele University put it: “While this is not the detection of life on another planet, it’s an important step in the right direction: the detection of an atmosphere around the super-Earth GJ 1132b marks the first time that an atmosphere has been detected around an Earth-like planet other than Earth itself.”

It’s not an exact match for Earth – its mass is roughly 1.6 times that of Earth, and it’s around 1.4 times the radius, but in planetary terms that’s a damned good match.

Two quick points to burst the bubble of optimism. The first is that while 39 light years away is just down the road in galactic terms, it’s still a long way away. How long? Well, at Voyager 1 speeds you’re looking at around 17,000 years to get there. That’s probably too long for most people to travel, barring some pretty astonishing improvements to medical science.

The second is that while we can only infer certain things about the planet’s atmosphere from that far away (other than that it has one), one thing we’ve figured out is that it’s likely to be hot: a surface temperature of 370 degrees Celsius seems likely. So even if by some remote chance it does host life, it won’t look much like us.

But how were the researchers able to learn anything about an exoplanet so far away? Using the ESO/MPG telescope in Chile, the scientists were able to study the dip in brightness registered as GJ 1132b passed in front of its host star – something it did every 1.6 days. When researchers realised that the planet appeared larger when observed through one wavelength band, they inferred that the planet must have an atmosphere that’s opaque at specific wavelengths. Modelling different variations suggested that an atmosphere high in water and methane would match the evidence coming from the telescope.

“With this research, we have taken the first tentative step into studying the atmospheres of smaller, Earth-like, planets,” Southworth explained. “The planet is significantly hotter and a bit larger than Earth, so one possibility is that it is a ‘water world’ with an atmosphere of hot steam.”

At 370 degrees Celsius, we’re talking very hot steam here, but there’s still good news to take from this. The kind of low-mass stars that host small exoplanets such as GJ 1132b are pretty common in the universe – far more so than our own sun. The fact that GJ 1132b seems to have had an atmosphere for billions of years is really encouraging, given low-mass stars tend to have increased magnetic activity, which often strips away exoplanetary atmospheres. In other words, even if GJ 1132b isn’t a perfect match, this research suggests there might be a lot more eligible fish in the sea than we thought.

Damien Phillips used under Creative Commons