June 21, 1863 – October 3, 1932
He was born in Heidelberg, Germany. In 1888 he was awarded a Ph.D. by the University of Heidelberg, and joined the staff of that institution in 1890.
Working at Landessternwarte Heidelberg-Königstuhl, he discovered more than 200 asteroids with the Bruce double-astrograph since 1891. The first one, 323 Brucia, was named after Catherine Wolfe Bruce, who had donated $10,000 for the construction of the telescope. He pioneered the use of astrophotographic techniques to automate the discovery of asteroids, as opposed to older visual methods, as a result of which asteroid discovery rates sharply increased. In time-exposure photographs, asteroids appear as short streaks due to their planetary motion with respect to fixed stars.
Among his many discoveries was 588 Achilles (the first Trojan asteroid) in 1906, as well as two other Trojans: 659 Nestor and 884 Priamus. He also discovered 887 Alinda in 1918, which is now recognized as an Earth-crossing Amor asteroid (or sometimes classified as the namesake of its own Alinda family). Shortly after his last discovery (on February 6, 1932), his record 248 discoveries were beaten by his pupil Karl Wilhelm Reinmuth, on July 24, 1933.
He also discovered or co-discovered some comets, including 14P/Wolf and 43P/Wolf-Harrington, and four supernovae: SN 1895A (a.k.a. VW Vir), 1909A (a.k.a. SS UMa), 1920A, and 1926A (the latter co-discovered by Reinmuth).
He also discovered Wolf 359, a red dwarf that is one of the nearest stars to our solar system. Note that Wolf-Rayet stars were co-discovered by French astronomer Charles Wolf and not by him.
In 1910 Wolf proposed to the Carl Zeiss optics firm the creation of a new instrument, now known as the planetarium. World War I intervened before this could be developed, but the Zeiss company returned to this after peace was restored, and the first successful planetarium was completed in 1923.