How did scientist discover exoplanets?

Answer 1

They are very difficult to detect as they cannot be seen directly; trying to see a relatively dark object (exoplanet) next to a very bright object (star) is virtually impossible. But they can be detected indirectly by several means:

• the star and the exoplanet orbit each other causing the star's location to "wobble"
• if the orbit of the exoplanet is in the plane of the earth/star then it will eclipse the star and these periodic dimmings of the star can be detected
• the star and the exoplanet orbit each other causing doppler shifts in the star's spectral lines
• etc.