Johann Christian Andreas Doppler
Christian Doppler (29 November 1803 – 17 March 1853) is known for relating the change in wavelength with movement, now known as the Doppler effect or Doppler shift, which he published in 1842. Dutch meteorologist Buys-Ballot used musicians sitting on a moving train to approach and recede from the observer to substantiate Doppler's theory that the frequency was higher while approaching and lower while moving away. This effect, discovered independently by Armand Fizeau in 1848, was also used to explain redshift in the light spectrum.
- Christian Doppler (1803–1853) and the impact of the Doppler effect in astronomy Wolfschmidt, Gudrun. Institute for History of Science, Hamburg University