Born March 24, 1893, in Germany, Wilhelm Heinrich Walter Baade earned his Ph.D. from the University of Gottingen in 1919. He went on to a career at the Hamburg Observatory, then, in the late 1920s, made his way to America on a Rockefeller fellowship. Growing Nazism in Germany prompted him to remain in the U.S., and Baade joined the staff of the Mount Wilson Observatory in 1931.
His German background earned him “enemy alien” status during World War II – and a curfew that would keep Baade from nighttime observations. But when a colleague was able to wrangle an exemption for him, the wartime blackout made for extraordinarily dark skies and groundbreaking discoveries. With Fritz Zwicky, Baade developed a new classification for incredibly bright celestial objects – supernovae – and proposed the existence of neutron stars. Baade also discovered Population I and Population II stars, and later developed two different classifications of Cepheid stars, allowing him to recalculate the size and age of the universe.
After his retirement in 1958, Baade returned to Germany and passed away there two years later, at age 67.
