Transit Photometry: Detecting Exoplanets by Shadows

Transit photometry finds exoplanets by measuring tiny dips in a star’s brightness.
A dip occurs when a planet passes—or transits—in front of its star.
The amount of dimming reveals the planet’s size relative to the star.
Repeated dips confirm the planet’s orbital period and distance from its star.
The method works best for stars with planets whose orbits line up with Earth.
NASA’s Kepler Space Telescope used this method to discover thousands of exoplanets.
The TESS mission is continuing the search across nearly the entire sky.
Transit photometry can also detect multiple planets in the same system.
Starlight passing through a planet’s atmosphere during transit reveals its chemical makeup.
This technique is the most successful method so far, accounting for the majority of known exoplanets.