Gerard Kuiper. Historical portrait of the Dutch-US astronomer Gerard Peter Kuiper (1905-1973). Kuiper studied at the University of Leiden in the Netherlands, where he obtained his PhD in 1933. In the same year he emigrated to the USA to continue his research. He discovered two new satellites: Miranda, the fifth satellite of Uranus (1948) and Nereid, the second satellite of Neptune (1949). In 1951 he proposed that short-period comets come from a flattened ring of debris (the Kuiper Belt), found just beyond the orbit of Pluto. He also studied planetary atmospheres, detecting carbon dioxide on Mars and, in 1944, detecting methane in the atmosphere of Titan, Saturn's largest moon.