sentences:  Doppler spectroscopy
  
  Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star.880 extrasolar planets (about 21.0% of the total) were discovered using Doppler spectroscopy, as of February 2020.