Finding Habitable Worlds

The Kepler Space Telescope discovered thousands of exoplanets, many in their star's habitable zone. Its successor, TESS, surveys nearby bright stars for transiting planets. The James Webb Space Telescope can analyze the atmospheres of some of these planets by studying starlight filtered through their air during transits.

Scientists look for biosignatures — atmospheric gases that should not coexist without life. Oxygen and methane together are unstable and would react away quickly without a biological source constantly replenishing them.