THE discovering extraterrestrial life is not a simple process, although Earth technology has made leaps and bounds in recent years. Placing telescopes outside the Earth’s atmosphere – essentially – paved the way for the study of planets outside our solar system.

The James Webb Telescope is studying dozens of planets, which may have atmospheres and water, and possibly life. Recently, James Webb made a very important discovery. Spot it carbon molecules in the planet’s atmosphere K2-18 ban exoplanet 8.6 times the size of Earth. Among the gases he detected were methane and carbon dioxide. Webb’s discovery adds to recent studies suggesting that K2-18 b could be an exoplanetwhich has the potential to have a hydrogen-rich atmosphere and a water-covered surface.

K2-18 b orbits the dwarf star K2-18 in the habitable zone and is located 120 light-years from Earth in the constellation Leo.

“Our findings highlight the importance of examining different habitable environments in the search for life elsewhere.”, explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper reporting these results. “Traditionally, the search for life on exoplanets has mainly focused on smaller rocky planetsbut the larger worlds of Hykei are significantly more favorable for atmospheric observations.”

The abundance of methane and carbon dioxide and the lack of ammonia support the hypothesis that a water ocean may exist under a hydrogen-rich atmosphere in K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life. Most of the DMS in the Earth’s atmosphere is emitted by phytoplankton in marine environments.

The conclusion of DMS is littlestronger and requires further validation. “Upcoming Webb observations should be able to confirm whether DMS is indeed present in the atmosphere of K2-18 b at significant levels”Madhusudhan explained.

While K2-18 b is in the habitable zone and is now known to host carbon-bearing molecules, this does not necessarily mean the planet can support life. The planet’s large size – with a radius 2.6 times that 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. However, it is also possible that the ocean is too warm to be habitable or that it is wet.

“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,” explained team member Subhajit Sarkar of Cardiff University. “We have obtained the most detailed spectrum of a sub-Neptune habitable zone to dateand this allowed us to calculate the molecules present in its atmosphere.”

The characterization of the atmospheres of exoplanets like K2-18 b – that is the determination of gases and their physical conditions – is a very active area in astronomy. However, these planets are overshadowed – literally – by the brightness of their much larger parent stars, which makes the exploration of exoplanet atmospheres particularly challenging.

James Webb circumvented this challenge by analyzing the light from K2-18 b’s parent star as it passed through the exoplanet’s atmosphere. K2-18 b is a transiting exoplanet, meaning we can detect a dip in brightness as it passes the face of its host star. This is how the exoplanet was first discovered in 2015 by NASA’s K2 mission. This means that during transits, a tiny fraction of starlight will pass through the exoplanet’s atmosphere before reaching telescopes like Webb. The passage of starlight through the exoplanet’s atmosphere leaves trails that astronomers can combine to determine the gases of the exoplanet’s atmosphere.

“This result was only possible because of Webb’s extended wavelength range and unprecedented sensitivity, which enabled robust detection of spectral features with just two passes”said Madhusudhan. “For comparison, one Webb transit observation provided comparable accuracy to eight Hubble observations conducted over a few years and over a relatively narrow wavelength range.”

“These results are the product of just two observations of K2-18 b. We still have many observations ahead of us,” explained Savvas Constantinou from the University of Cambridge. “That means our work here is just an early demonstration of what Webb can do in observing habitable-zone exoplanets.”

The team’s results have been accepted for publication in The Astrophysical Journal Letters.