In September, NASA announced that the James Webb Space Telescope (JWST) had detected potentially convincing evidence of life on an exoplanet about 120 light years from Earth. The atmosphere of K2-18b, a planet about nine times the size of our own, was found to contain methane, carbon dioxide, and—most tantalizing—a molecule called dimethyl sulfide. On Earth, DMS is only produced by life; the bulk of DMS in our atmosphere is released by phytoplankton.
While the discovery triggered an avalanche of little-green-men coverage, even the researchers involved in the investigation urged reserve, saying the findings needed further verification. What they were willing to celebrate, however, was the incredible observational power of the JWST and how good scientists are getting at analyzing the atmosphere of distant worlds.
In the case of K2-18b, researchers were able to search for signs of life by analyzing the light of its parent star as it passed through the exoplanet’s atmosphere. This method, called spectroscopy, is the most probable way we will find life on one of the more than 5,000 exoplanets we’ve discovered beyond our solar system, but there are other ways too.
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