The Dutch astronomer Jan Hendrik Oort (1900-1992) overturned the idea that our sun is at the center of the Milky Way galaxy. He contributed greatly to knowledge about the structure and evolution of our galaxy, and also discovered the place of origin of most comets, the Oort Cloud.

Jan Oort was born on April 28, 1900, in the farming village of Franeker in Holland. At the age of 17 he entered the University of Groningen and earned his doctoral degree in 1926. He received the Bachiene Foundation Prize (1920), undertook research at the Leiden Observatory (1924), and lived abroad as a research associate at the Yale University Observatory (1924-1926).

In 1926 Oort became an instructor at the University of Leiden, and the following year he married Johanna M. Graadt van Roggen. They had three children, sons Coenraad and Abraham and a daughter, Marijke. Oort became a professor of astronomy (1935) and director of the observatory (1945) at...