An Earth-sized planet orbiting a dim star 39 light years away has a hazy atmosphere that could indicate the presence of a “water world”.
It is one of the first times astronomers have been able to detect an atmosphere surrounding a small rocky planet.
Similar observations using the next generation of powerful telescopes could be used to look for life outside the solar system.
Until now, scientists have mostly been able to spot the atmospheres of giant “hot Jupiter” exoplanets that are very unlikely to support life.
The super-Earth planet GJ 1132b was observed as it passed in front of a cool red dwarf star, blocking out some of the star’s light.
By measuring the slight drop in the star’s brightness, astronomers were able to work out that the planet was 1.4 times the size of Earth.
They also found that in one light wavelength band, the planet looked slightly bigger. This could be explained by an atmosphere that was opaque to some light wavelengths, but transparent to others.
“While this is not the detection of life on another planet, it’s an important step in the right direction,” says John Southworth at the University of Keele, who led the team.
The detection of an atmosphere around GJ 1132b marks the first time that an atmosphere has been detected around a planet less than twice the size of Earth. Previously, we had seen a waterless atmosphere around the planet 55 Cancri e, which is between 6 and 8 times Earth’s mass.
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