Forget Mars, are there aliens on… K2-18b? The discovery of a planet twice the size of Earth that emits gas “only produced by life” generates great enthusiasm among astronomers

Astronomers were finally able to prove that extraterrestrial life exists on a distant planet after observations made today.

Planet K2-18b, which is more than twice the size of Earth and 120 light-years away, lies within the habitable zone of its star in the constellation Leo.

Scientists said last year that they believed they had detected dimethyl sulfide gas in its atmosphere, a compound that “is only produced by life.”

Now, to confirm the finding, the James Webb Space Telescope will conduct hours of observations of the planet on Friday.

However, space fans will have to wait several months for the results to be authenticated and published.

Investigations of planet K2-18b are led by Dr. Nikku Madhusudhan, an astrophysicist at the University of Cambridge.

He called it a ‘Hicean’ world, a relatively new term he coined to refer to a rocky planet with a hydrogen-rich atmosphere and water oceans.

“If we detect DMS (on K2-18b), we’ll basically put it at the top of possible signs of habitability,” he said. the times.

K2-18b, more than eight times the mass of Earth and more than twice its size, was discovered in 2015.

But it was not until 2019 that the presence of water vapor in the atmosphere of K2-18b was reported.

Then, last year, the James Webb telescope detected carbon dioxide and methane in its atmosphere, as well as a shortage of ammonia.

Dr. Madhusudhan called this a “very profound moment” because it supports the theory that there is an ocean of water beneath a hydrogen-rich atmosphere.

But it was the presence of something else that excited astronomers even more.

Webb’s initial observations provided a possible detection of a molecule called dimethyl sulfide (DMS), which on Earth “is only produced by life.”

Most of the DMS in Earth’s atmosphere is emitted by phytoplankton in marine environments, suggesting a similar way of life on the distant planet.

In fact, scientists have been unable to think of any natural geological or chemical process that could create DMS without living organisms.

Dr Madhusudhan said the finding came as a shock, but as these were initial observations, he could only say with 50 per cent confidence that there is DMS in K2-18b.

“It was a real shock, I had sleepless nights for a week,” he added.

“That week, I didn’t even work up the courage to tell my own team.”

Today, eight hours of observations by the James Webb telescope should provide a definitive answer, although the expert will have to spend months studying the data to obtain it.

NASA’s $10bn (£7.4bn) observatory is capable of analyzing the chemical composition of a distant planet by capturing light from its host star after it has passed through the planet’s atmosphere on its way to the earth.

Gases in the atmosphere absorb some of the starlight, but each of them leaves telltale fingerprints in the light spectrum that astronomers can then detect.

Although Hycean worlds are predicted to be covered in water, researchers say it is also possible that K2-18 b’s putative ocean is too hot to be habitable or liquid.

In fact, a study published earlier this year suggested that the ocean may be lava.

K2-18b is known as a “super Earth” because it is larger than our planet but smaller than Neptune.

The large size of K2-18b (with a radius 2.6 times the radius of Earth) means that the planet’s interior likely contains a large, high-pressure ice mantle, like Neptune, but with a thinner, hydrogen-rich atmosphere. and an ocean surface.

“Although this type of planet does not exist in our solar system, sub-Neptunes are the most common type of planet known so far in the galaxy,” said researcher Subhajit Sarkar of Cardiff University.

“We have obtained the most detailed spectrum to date of a sub-Neptune in the habitable zone, which has allowed us to determine the molecules that exist in its atmosphere.”