1Today we will survey the principal methods astronomers use to detect planets orbiting stars beyond our solar system.
2The first confirmed exoplanets were announced in the early nineties, orbiting not a normal star but a pulsar.
3What I want to emphasize here is that almost all exoplanets are found indirectly, through their effects on the host star.
4The transit method measures the slight dimming that occurs when a planet passes directly in front of its star.
5It is not the size of the planet alone but the size relative to the star that determines the signal.
6The radial velocity technique, by contrast, detects the tiny wobble a planet's gravity imparts to its star.
7Early surveys suggested hot Jupiters were common, though further analysis revealed this was largely a selection effect.
8The mission was originally planned to last three and a half years, yet it continued collecting data for nine.
9Moving on to direct imaging, this approach remains extremely challenging because starlight overwhelms the faint reflected light.
10Let me give you a concrete example: the first directly imaged system contained four enormous planets around a young star.
11To sum up, each method carries its own biases, and combining them gives the clearest picture of distant worlds.