The Transit Method

The most productive technique is the transit method. When a planet crosses in front of its star, it blocks a tiny fraction of starlight — typically 0.01% to 1% depending on size. Precise measurement reveals the planet's size, orbital period, and distance.

The Kepler Space Telescope used the transit method to discover over 2,600 confirmed exoplanets by staring at 150,000 stars for four years. Its successor, TESS, surveys the entire sky, focusing on nearby bright stars where follow-up is easier.