Finding new worlds with a play of light and shadow

One method to discover planets beyond the solar system by far is transit photometry, which measures changes in a star’s brightness when a planet crosses in front of its star along our line of sight. NASA’s Kepler Space Telescope has used this technique to become the most successful planet-hunting spacecraft to date, with more than a thousand established discoveries. Satellites carrying improved technology for all-sky surveys are now planned, missions that will tell us a great deal about alien planetary systems similar to our own.