Astronomers have discovered an atmosphere around an Earth-like exoplanet for the first time, marking a major step forward in the search for alien life.

With a mass and radius slightly greater than that of our own, planet GJ 1132b is said to be a ‘super-Earth,’ and sits just 39 light-years away.

Recent observations revealed that the planet appears larger in one wavelength than it does in others as it passes in front of its host star – and researchers say an atmosphere rich in water and methane could be to blame.

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Astronomers have discovered an atmosphere around an Earth-like exoplanet for the first time, marking a major step forward in the search for alien life. With a mass and radius slightly greater than that of our own, planet GJ 1132b is said to be a ‘super-Earth,’ and sits just 39 light-yrs away

WHAT THEY FOUND GJ 1132b passes in front of its star every 1.6 days, from the perspective of viewers on Earth. And during its transit, the researchers found that it appeared to be larger at just one of the infrared wavelengths. This suggests that it is surrounded by an atmosphere that is opaque to this specific wavelength of light, causing it to appear larger. At all other infrared wavelengths, however, the atmosphere is transparent. Simulations revealed a number of scenarios that could explain the phenomenon, including an atmosphere that is rich in water and/or methane. The researchers say it could be a planet with a ‘nearly Earth-like rocky interior’ composed of roughly 70 percent silicate and 30 percent iron Or, it could be a ‘water world with an atmosphere of hot steam.’ Advertisement

Gliese 1132b (or GJ 1132b) lies in the southern constellation Vela, and orbits a red dwarf star.

It’s estimated to be 1.4 times the size of Earth and contain 1.6 times our planet's mass, and researchers say the discovery of an atmosphere is reason for ‘cautious optimism.’

‘While this is not the detection of life on another planet, it’s an important step in the right direction,’ said Dr John Southworth of Keele University.

‘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.’

A team of scientists, including researchers from the Max Planck Institute for Astronomy, observed nine transits of the planet using the GROND imager at the 2.2 meter ESO/MPG telescope in Chile.

As a planet crosses in front of its star, it blocks out some of the light – and, by measuring this effect, researchers can determine the planet’s size.

GJ 1132b passes in front of its star every 1.6 days, from the perspective of viewers on Earth.

And during its transit, the researchers found that it appeared to be larger at just one of the infrared wavelengths.

This suggests that it is surrounded by an atmosphere that is opaque to this specific wavelength of light, causing it to appear larger.

At all other infrared wavelengths, however, the atmosphere is transparent.

In the study, published to arXiv, the researchers argue that there are a number of possible interior compositions that could explain these observations.

This includes a ‘nearly Earth-like rocky interior’ composed of roughly 70 percent silicate and 30 percent iron, and a ‘substantially H20-rich water world.’

Gliese 1132b (or GJ 1132b) lies in the southern constellation Vela, and orbits a red dwarf star. GJ 1132b passes in front of its star every 1.6 days, from the perspective of viewers on Earth. An artist's impression of the planet is pictured

‘With this research, we have taken the first tentative step into studying the atmospheres of smaller, Earth-like planets,’ Dr Southworth says.

‘We simulated a range of possible atmospheres for this planet, finding that those rich in water and/or methane would explain the observations of GJ 1132b.

‘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.’

But, the authors note that future observations are critical to confirm their findings.

Moving forward, they say the planet is now a high-priority target for study, and instruments such as the Hubble Space Telescope, the ESO’s Very Large Telescope, and the emerging James Webb Space Telescope could one day tell us more about it.