Interstellar comets hide methane deep beneath their surface

When the interstellar comet 3I/ATLAS streaked through our solar system, it initially appeared to be a standard ball of ice and dust. However, as it rounded the sun and began its journey back into the deep freeze of space, the James Webb Space Telescope captured something unprecedented. For the first time, astronomers detected methane on an object from another star system, but the gas only appeared after the comet had already passed its closest point to the sun.