
The first confirmed discovery of exoplanets took place in 1992 around the pulsar PSR B1257+12. In 1995, Michel Mayor and Didier Queloz discovered the first exoplanet around a solar-type star — 51 Pegasi b, for which they received the Nobel Prize. Since 2009, the Kepler space telescope (with William Borucki involved in its development) has discovered thousands of planets by the transit method.
Exoplanets are found by observing the star's light: when a planet passes between us and the star, the star dims by a fraction of a percent—as if a fly flew in front of a light bulb. Another method: the planet, by its gravity, makes the star wobble slightly, and from the spectrum shift we determine its mass.