A super-Earth just discovered in our cosmic backyard may contain an atmosphere

About 26 light years from Earth is Gliese 486, a red dwarf star. These types of stars are strewn across the Milky Way; they are practically everywhere. But we can’t see any of them from Earth when we look up into the night sky, because they’re just not very bright. Gliese 486 is no exception. However, if you have a good enough telescope yourself, the Gliese 486 cannot hide.

Astronomers, studying the star over a four-year period between 2016 and 2020, noticed periodic drops in its brightness – telltale signs of an orbiting exoplanet. In a study published Thursday in the journal Science, researchers detail the discovery of the planet, called Gliese 486 b. It is the third closest exoplanet discovered with this method. Thousands of planets have now been discovered in our galaxy, but Gliese 486b is particularly noteworthy because astronomers believe we might be able to study whether the planet has an atmosphere.

The rocky world is slightly larger than Earth but three times as massive (a so-called “super-Earth”) and makes a full orbit of its mother star in less than 1.5 days. Data from two exoplanet hunting missions, NASA’s TESS, a space telescope, and the Carmenes survey, by the Spanish Calar Alto observatory, which specifically searches for planets around red dwarfs, was obtained to study the newly discovered planet.

While we’ve found a ton of exoplanets, they’re not easy to see. Planets don’t reflect much light, so you have to find them indirectly. One way to do this is to look for dips in a star’s luminosity, the “transit” method, which means a planet moving in front of the star. Another is to assess how a star’s radial velocity changes, which happens when a planet pulls at the star and it appears to “wobble” when observed. For Gliese 486b, both methods were used – giving researchers a powerful tool to further define the characteristics of the planet.

Researchers write that Gliese 486b is not a hell planet made of lava, like some of the exoplanets we found near the stars. On the contrary, its surface is a soft 800 degrees Fahrenheit, which makes it cooler than Venus but still hot enough to melt lead. “Its temperature … makes it suitable for emission spectroscopy and phase curve studies looking for an atmosphere,” the team writes.

Spectroscopy allows researchers to split light into its different wavelengths, which can tell them about the chemical composition of its atmosphere. It wouldn’t be the first time we could assess the atmosphere of a super-Earth, this honor goes to 55 Cancri e, but 486 b would be the closest yet and could give us clues about the habitability of the planet.

There is no reason to think that we would find life there, but an atmosphere would certainly help. And with recent discussions around “life” on Venus, it may be worth investigating.

The much delayed James Webb Space Telescope expected to launch later this year, will also be able to observe exoplanets like this one and begin to slowly lift the cosmic curtain off the worlds hidden in deep space.

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