![An illustration of what exoplanet K2-18 b could look like based on science data of its atmosphere. Credit: NASA/ESA/CSA/Joseph Olmsted (STScI)](https://www.spaceflightinsider.com/wp-content/uploads/2023/09/K2-18b.jpg)
An illustration of what exoplanet K2-18 b could seem like based on science data of its atmosphere. Credit: NASA/ESA/CSA/Joseph Olmsted (STScI)
NASA says data from the James Webb Space Telescope shows evidence of “carbon-bearing” molecules within the atmosphere of K2-18 b, an exoplanet situated some 120 light years away around its host star’s habitable zone.
During two recent observations, Webb revealed the presence of methane and carbon dioxide in K2-18 b’s atmosphere, adding to previous Hubble Space Telescope observations that showed evidence the planet possesses a hydrogen-rich atmosphere and a water ocean-covered surface, in accordance with NASA.
K2-18 b was discovered in 2015 by the Kepler Space Telescope. It orbits its host red dwarf star every 33 days at a distance of about 13 million miles, roughly one-third the space between Mercury and the Sun in our solar system.
Nevertheless, because red dwarf stars are smaller and cooler in comparison with the Sun, this exoplanet is within the star’s habitable zone, an area where water may very well be liquid on a planet’s surface under the fitting circumstances.
K2-18 b is about 8.6 times as massive as Earth and classified as a “mini-Neptune,” meaning it has a mass greater than Earth, but lower than Neptune. Such a planet doesn’t exist in our solar system and, in accordance with NASA, this category of exoplanets is poorly understood and the character of their atmospheres “is a matter of energetic debate amongst astronomers.”
“Our findings underscore the importance of considering diverse habitable environments within the search for all times elsewhere,” Nikku Madhusudhan, an astronomer on the University of Cambridge and lead creator of the paper announcing these results, said in a Sept. 11 NASA news release. “Traditionally, the search for all times on exoplanets has focused totally on smaller rocky planets, however the larger Hycean worlds are significantly more conducive to atmospheric observations.”
K2-18 b is believed to potentially be a “hycean” world, which is a planet that’s hot and water-covered with a hydrogen atmosphere. NASA said this sort of exoplanet is believed by astronomers as having promising environments for all times.
NASA said the abundance of methane and carbon dioxide with a shortage of ammonia supports the hypothesis that there is perhaps water oceans underneath K2-18 b’s hydrogen wealthy atmosphere.
One other molecule potentially detected was dimethyl sulfide, also called DMS. On Earth, this molecule is just produced by life, typically from phytoplankton in marine environments, in accordance with NASA.
![The spectra of the atmosphere of K2-18 b obtained by the Webb telescope. Credit: NASA](https://www.spaceflightinsider.com/wp-content/uploads/2023/09/stsci-01h9rf3tqe6xa9x01kxxj351z6.jpg)
The spectra of the atmosphere of K2-18 b obtained by the Webb telescope. Credit: NASA
But scientists say there shouldn’t be enough data to verify the presence of DMS and extra observations of the planet can be required to grasp if it is definitely present and at significant levels.
NASA cautioned, nonetheless, that even when all of those molecules are confirmed, it doesn’t mean the planet can support life.
The agency said the planet has a radius 2.6 times that of Earth and can have a mantle of high-pressure ice, like Neptune, but a thinner hydrogen wealthy atmosphere and an ocean surface. Still, NASA said its possible a K2-18 b ocean is perhaps too hot to be habitable, and even liquid.
K2-18 b is outshined by its host star and can’t be directly observed by Webb. As such, astronomers must use the “transit method” to review the exoplanet.
When a planet passes in front of its parent star, the star’s brightness dims ever so barely. Detectors on Webb, or every other telescope observing such a transit, can measure the difference in brightness, in addition to the composition of sunshine that passes through the planet’s atmosphere because the photons make their strategy to our solar system.
NASA said an evaluation of that light will be done to piece together the gasses of the exoplanet’s atmosphere.
“These results [from K2-18 b] are the product of just two observations of K2-18 b, with many more on the best way,” team member Savvas Constantinou of the University of Cambridge said in NASA’s news release. “This implies our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets.”