It's Not Conclusive, But Methane is Probably the Best Sign of Life on Exoplanets

When the James Webb Space Telescope aims at exoplanet atmospheres, it’ll use spectroscopy to identify chemical elements. One of the things it’s looking for is methane, a chemical compound that can indicate the presence of life. Methane is a compelling biosignature. Finding a large amount of methane in an exoplanet’s atmosphere might be our most …