UNDERSTANDING OTHER WORLDS
What is the transit method?
A tiny, regularly repeating dip in starlight can reveal a planet crossing its star.
The light curve
Astronomers measure brightness over time. The depth, duration and repeating pattern of a dip constrain a planet’s radius and orbit, together with information about its star.
A particular viewing angle
The orbital plane must line up with our view. A star without observed transits may still have planets. Close-in planets transit more frequently and are easier to find, which shapes the catalogue.
Looking through an atmosphere
During a transit, a small amount of starlight passes through the planet’s atmosphere. Spectral features may constrain gases, but clouds, stellar effects and competing models make interpretation challenging.