German-American astronomer who discovered the asteroids Hidalgo in 1920 and Icarus in 1948. Studying the distances and stellar populations of nearby galaxies, he showed that Hubble's distances were incorrect because there were actually two populations of Cepheid variables. The two have different metal abundances and each has its own characteristic period-luminosity relationship. He also discovered a one-sided polarized jet in M87 in 1956. Baade found nearly complete polarization of emission from the Crab nebula, which led to the identification of the mechanism as synchotron radiation. With Rudolph Minkowski, Baade identified the optical counterparts of the radio sources Cygnus A, Virgo A (M87), Perseus A (NGC 1275), and Centaurus A (NGC 5128). He also identified the Crab nebula as the remnant of the supernova of 1054.

Hubble, Minkowski (Rudolph)

Additional biographies: Bonn