Radial Velocity Method

The radial velocity method detects exoplanets by measuring the Doppler shift of a star's spectral lines caused by gravitational tugging from orbiting planets. When a planet orbits a star, the star wobbles slightly toward and away from Earth, creating periodic shifts in its light spectrum. First proposed by Friedrich Wilhelm Bessel in the 19th century and successfully applied to exoplanet detection in 1995, this method has discovered nearly half of all known exoplanets.