Hermann Vogel. Portrait of Hermann Carl Vogel (1841-1907), German astronomer. Vogel introduced photographic methods into stellar spectroscopy. He was the first to achieve enough accuracy to measure the radial velocity of stars. In 1889 he discovered the first eclipsing binary star, Algol (beta Persei). He proved the Sun rotated by measuring the Doppler shift of its light, and discovered carbon monoxide in comet tails. The Potsdam observatory became one of the world's leading astrophysical centres under his directorship. Vogel continued in office to his death, though in later years was a recluse whose main interest was playing a huge organ.