Discover exoplanets using the transit and radial velocity methods.
Transit method: When a planet crosses in front of its star, the star's brightness dips slightly. The dip size reveals planet radius; interval reveals orbital period. Radial velocity: A planet's gravity causes its star to wobble. Spectral blueshifts/redshifts reveal the wobble speed, giving planet mass. Kepler discovered 2,600+ exoplanets via transits.