Transcript: About one percent of all galaxies and ten percent of all active galaxies have high levels of radio emission. Stars like the Sun and all other normal stars have very low levels of radio emission. So the sum of stellar populations can not produce such radio emission. In 1944 the amateur astronomer Grote Reber detected sources of radio emission in the constellations of Sagittarius, Cassiopeia, and Cygnus. The Sagittarius source was the galactic center. The Cassiopeia source was a supernova remnant. But the source in Cygnus could not be identified until 1951 when at Palomar Walter Baade and Rudolph Minkowski identified the intense radio emission with a faint galaxy at a distance of two hundred and thirty megaparsecs. This galaxy Cygnus A has ten million times the radio emission of the nucleus of the Milky Way, yet it can be detected with the radio equipment of a backyard amateur radio astronomer.