Ernst Gräfenberg Ernst Gräfenberg Ernst Gräfenberg (September 26, 1881 in Adelebsen near Göttingen, Germany – 28 October 1957 in New York City, United States) was a German-born physician (medical doctor) and scientist. He is known for developing the intrauterine device (IUD), and for his studies of the role of the woman's urethra in orgasm. The G-spot is named after him. Gräfenberg studied medicine in Göttingen and Munich, earning his doctorate on 10 March 1905. He began working as a doctor of ophthalmology at the university of Würzburg, but then moved to the Department of Obstetrics and Gynaecology at the University of Kiel,
Ernst Hartwig 1902 for his heliometer observations and work on variable stars. Craters on the Moon and on Mars were named in his honor. Ernst Hartwig Carl Ernst Albrecht Hartwig (14 January 1851 in Frankfurt – 3 May 1923 in Bamberg) was a German astronomer. He discovered a new star in M31 (the "Andromeda Nebula") on 20 August 1885. This object was designated as supernova "S Andromedae". He observed the 1882 transit of Venus in Argentina. During the 1883 observation campaign of comet 6P/d'Arrest he found five NGC objects working at the Strasbourg Observatory. In 1874 he became assistant at Strassburg Observatory,