The NASA space agency on Monday announced the potential discovery of a water ocean surface on a planet outside the solar system, as well as a certain molecule that may hint at the existence of life.
Data collected by the agency’s James Webb Telescope on K2-18 b, a planet orbiting a dwarf star 120 light years from Earth in the Leo constellation, suggested evidence of methane, carbon, and a shortage of ammonia, indicating it is a Hycean exoplanet — a planet with a hydrogen atmosphere and covered in water.
Furthermore, the observations detected the possibility of dimethyl sulfide (DMS) on the planet, a chemical that is only produced by living organisms on Earth — mainly phytoplankton.
“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,” said astronomer Nikku Madhusudhan of Cambridge University, who was a lead author on the research paper publishing the findings.
“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,” he added.
Madhusudhan said the findings are not conclusive and further research will be conducted to determine if DMS indeed exists on the distant planet, which is eight-and-a-half times larger than Earth.
“Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the universe,” he said. “Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest.”
The planet was originally discovered and studied in 2015 with data from the Hubble Space Telescope.
NASA said that although K2-18 b exists in the so-called habitable zone — the appropriate distance from a sun that would allow life on a planet to bloom — they presume the world is similar to Neptune due to its size, with “a large mantle of high-pressure ice,” and “a thinner hydrogen-rich atmosphere and an ocean surface.”
The Astrophysical Journal Letters accepted the Cambridge researchers’ paper.
James Webb’s MIRI (Mid-Infrared Instrument) spectrograph camera will be used to further probe the world’s environment and potentially discover new findings, NASA said.
The statement noted that the study of planets such as K2-18 b is challenging since they are blocked by the glare of nearby stars.
“The team sidestepped this challenge by analyzing light from K2-18 b’s parent star as it passed through the exoplanet’s atmosphere. K2-18 b is a transiting exoplanet, meaning that we can detect a drop in brightness as it passes across the face of its host star,” NASA said.
“This is how the exoplanet was first discovered in 2015 with 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 starlight’s passage through the exoplanet atmosphere leaves traces that astronomers can piece together to determine the gases of the exoplanet’s atmosphere,” the space agency added.
NASA has hailed the potential discovery of water on exoplanets in the past. In 2022, the agency said it detected water vapor on HAT-P-11b, another Neptune-like planet 120 light years away, in the Cygnus constellation.