Baade

Baade is a German-language surname. The name is best known for Walter Baade (1893–1960), a German-American astronomer whose work helped shape modern observational cosmology and the study of stellar populations.

Baade spent much of his career at major observatories in the United States and made foundational contributions to extragalactic astronomy. In 1934, together with Fritz Zwicky, he proposed the classification of supernovae into two main types, Type I and Type II, a framework still used in supernova research.

Baade also introduced the concept of stellar populations in galaxies, distinguishing younger, metal-rich Population I stars from older, metal-poor Population II stars. This framework improved understanding of the structure and evolution of the Milky Way and other galaxies, and influenced subsequent studies of stellar content across the universe.

In the mid-20th century, Baade helped refine the cosmic distance scale, contributing to revisions that affected estimates of distances to external galaxies and the inferred value of the Hubble constant.

Baade's Window is a region toward the Galactic bulge with relatively low interstellar extinction, named after him. It provides a clearer view of bulge stars and has been a key area of observational study in stellar populations and galactic structure.

Outside of Walter Baade, the surname is relatively uncommon, and the term Baade is primarily encountered in astronomical history, biographies, and discussions of 20th-century cosmology.