TRAPPIST-1 is a nearby system of seven Earth-sized, temperate, rocky exoplanets transiting a Jupiter-sized ultracool red dwarf, ideally suited for in-depth atmospheric studies. Using the NIRISS instrument aboard the NASA/ESA/CSA James Webb Space Telescope, astronomers have now captured the first transmission spectra of TRAPPIST-1b, the innermost planet in the TRAPPIST-1 system. An artist’s impression of the rocky planet TRAPPIST-1b. Image credit:...