Researchers announced the discovery on Monday that an exoplanet, K2-18 b, over eight times the size of Earth has the potential to have a hydrogen-rich atmosphere with an ocean-covered surface, according to NASA.
The first insights into the exoplanet K2-18 b, came back in 2019 when astronomers made an important step toward the goal of finding an exoplanet with an atmosphere like Earth’s. K2-18 b orbits the cool dwarf star K2-18 in the habitable zone. It is 8.6 times bigger than our planet and it lies 120 light-years from Earth in the Leo constellation, according to NASA. Researchers examined the exoplanet with NASA’s James Webb Space Telescope.
Astronomers led by the University of Cambridge found methane and carbon dioxide in the atmosphere of the exoplanet.
“The discovery provides a glimpse into a planet unlike anything else in our Solar System, and raises interesting prospects about potentially habitable worlds elsewhere in the Universe,” according to the University of Cambridge.
Researchers identified K2-18 b as belonging to a new class of habitable exoplanets called “Hycean” worlds. This new class of exoplanets could “accelerate the search for life elsewhere,” per the university. (RELATED: NASA Makes History With First Helicopter Flight On Another Planet).
“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,” Nikku Madhusudhan, University of Cambridge astronomer and lead author of the paper announcing these results, said.
“Traditionally, the search for life on exoplanets has focused primarily on rocky planets, but Hycean worlds are significantly more conducive to atmospheric observations,” he continued.
While K2-18 b lies in the habitable zone, this doesn’t necessarily mean the planet can support life. The large size of the planet means that the interior likely contains a large mantle of high-pressure ice, similar to Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface, NASA explained. Hycean worlds are predicted to have oceans of water however, there is the possibility that the ocean is too hot to be habitable or to be liquid.
The abundance of methane and carbon dioxide, and shortage of ammonia support the hypothesis that the exoplanet might be covered in ocean, according to NASA.
Our @NASAWebb telescope detected carbon dioxide and methane in the atmosphere of a planet orbiting a faraway sun. The planet might have an ocean, but more observations are needed to determine whether it could support life: https://t.co/J8ub8PqwMG pic.twitter.com/SbgHjOO9Hv
— NASA (@NASA) September 11, 2023
The initial Webb observations also provided a possible detection of dimethyl sulfide (DMS), a molecule that is produced by life on Earth. The majority of DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments, per NASA.
The research team intends to conduct follow-up research with the telescope MIRI (Mid-Infrared Instrument) spectrograph. They hope to further validate their findings and provide new insights into the environmental conditions of K2-18 b.