The James Webb Space Telescope has discovered an organic molecule in the atmosphere of a distant exoplanet that could indicate the presence of life thriving in a vast global ocean, although more observations are needed to confirm this.
The exoplanet K2-18 b is thought to orbit in the habitable zone of an exotic star about 120 light-years from Earth in the constellation Leo. Previous observations of the distant world, which is about 2.6 times larger than Earth, have led some scientists to believe it could belong to a newly discovered type of potentially habitable planet known collectively as “Hessian worlds.”
These planets are essentially mini-Neptunes, with hydrogen-rich atmospheres, globe-spanning oceans, and the ability to sustain microbial life. Now, a new study of K2-18 b using data collected by the James Webb Space Telescope (JWST) has revealed more about the strange planet’s true nature.
our @NASAWeb The telescope has detected carbon dioxide and methane in the atmosphere of a planet orbiting a distant sun. The planet may have an ocean, but more observations are needed to determine if it could support life: https://t.co/J8ub8PqwMG pic.twitter.com/SbgHjOO9Hv
– NASA (@NASA) September 11, 2023
Normally, sub-Neptunian worlds, such as K2-18 b, are difficult to observe due to the deluge of radiation streaming from their parent stars. However, in the case of K2-18 b, astronomers were able to capture light from the parent star that traveled through the atmosphere of the planet it orbits.
“This result was only possible due to the extended wavelength range and unprecedented sensitivity of the Webb, which enabled robust detection of spectral features with just two transits.” Nico Madhusudan said from the University of Cambridge, lead author of the paper describing the JWST observations accepted for publication in Astrophysical Journal Letters. “For comparison, one transit observation with the Webb provided a resolution comparable to eight Hubble observations made over a few years in a shorter wavelength range.”
By analyzing the chemical signature imprinted in starlight, the team was able to detect the presence of methane and carbon dioxide in the exoplanet’s atmosphere, supporting the theory that K2-18 b could indeed be a Hessian world.
Astronomers also discovered evidence of the rare molecule dimethyl sulfide in the light spectrum, which would be a strong indicator of the presence of life. On Earth, dimethyl sulfide is created only as a byproduct of life, most commonly by marine bacteria and microscopic organisms known as phytoplankton.
“Our ultimate goal is to identify life on a habitable exoplanet, which would change our understanding of our place in the universe,” Madhusudan explained. “Our findings are a promising step toward a deeper understanding of the Hessian worlds in this endeavor.”
Astronomers warn that more observations using Webb will be needed to confirm the presence of the biomarker in the alien world’s atmosphere. It’s also possible that radiation from parent star K2-18 b has made its giant ocean too hot to support life as we understand it.
The team behind the James Webb Space Telescope plans to make observations of the oceanic planet using the telescope’s mid-infrared (MIRI) instrument, which could shed more light on the true nature of the alien world.
“Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere,” Madhusudan said. “Traditionally, the search for life on exoplanets has focused primarily on smaller, rocky planets, but larger Hessian worlds are more suitable for atmospheric observations.”
Anthony is a freelance contributor covering science and video game news for IGN. He has over eight years of experience covering breaking developments in multiple scientific fields and has absolutely no time to fool you. Follow him on Twitter @BeardConGamer
“Typical beer advocate. Future teen idol. Unapologetic tv practitioner. Music trailblazer.”
More Stories
The glow of an exoplanet may be caused by starlight reflecting off liquid iron
Exploring the “cosmic imbalance” in gravity
Has the James Webb Space Telescope really discovered extraterrestrial life? Scientists aren’t so sure about that