Gas Discovery Hints at Life on Distant Planet

exoplanet K2-18 b
This artist’s concept shows what exoplanet K2-18 b could look like based on science data. | Image by NASA, CSA, ESA, J. Olmsted (STScI)

Astronomers have discovered the potential for life on a distant world.

NASA announced on Monday that scientists have discovered evidence of carbon-bearing molecules including methane and carbon dioxide on a planet known as K2-18 b.

Scientists believe that the discovery of these compounds on this planet could point to the potential for habitability and life.

K2-18 b is classified as a super earth exoplanet and is approximately 8.6 times the mass of the Earth, according to NASA. The planet was discovered in 2015 and orbits a red dwarf star 124 light years away from Earth.

In addition to orbiting its parent star in the Goldilocks — or habitable — zone, scientists also theorized that K2-18 b is a Hycean planet, otherwise known as a planet with the potential for a hydrogen-rich atmosphere and an ocean surface.

Scientists previously discovered water vapor in the atmosphere of the planet back in 2019.

Using the James Webb Space Telescope, scientists studied K2-18 b and discovered the existence of carbon dioxide and methane in the planet’s atmosphere, supporting the hypothesis that a water ocean could one day be found underneath a hydrogen-rich atmosphere.

Researchers came to these conclusions by analyzing light from K2-18 b’s parent star as it passed through the planet’s atmosphere.

“Although this kind 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 Subhajit Sarkar, who worked on the recent study, according to a September 11 news release from NASA. “We have obtained the most detailed spectrum of a habitable-zone sub-Neptune to date, and this allowed us to work out the molecules that exist in its atmosphere.”

Scientists believe that the existence of these compounds and a deficit of ammonia support the notion that this planet could be a Hycean world — a water-covered planet with a hydrogen atmosphere.

In addition to discovering these properties, scientists also recorded a possible detection of a molecule known as dimethyl sulfide (DMS). This substance is typically only produced by life forms on the surface of Earth, such as phytoplankton.

“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,” said Nikku Madhusudhan, an astronomer and lead author of the study. “Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations.”

Madhusudhan said that upcoming observations will confirm if DMS is abundant on the planet. Scientists plan to use the James Webb telescope’s mid-infrared instrument spectrograph to further validate their findings.

“Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the universe,” said Madhusudhan. “Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest.”

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