Christian Doppler, Austrian mathematician and physicist (d. 1853)
Christian Andreas Doppler ( (German: [ˈdɔplɐ]; 29 November 1803 – 17 March 1853) was an Austrian mathematician and physicist. He is celebrated for his principle – known as the Doppler effect – that the observed frequency of a wave depends on the relative speed of the source and the observer. He used this concept to explain the colour of binary stars.