Jansky built directional antenna at Bell Labs to track radio static. He categorized static into nearby thunderstorms, distant thunderstorms, and faint hiss. Hiss peaked every 23 hours 56 minutes, matching sidereal day. Signal came from Milky Way center in Sagittarius. Discovery announced April 1933, published October 1933. Sun produced no such radio noise. Jansky suggested interstellar gas caused signals via thermal agitation. Bell Labs halted further research due to Depression costs. Astronomers ignored it as foreign field. Grote Reber built first radio telescope in 1937. Jansky died at 44 from heart condition. Jansky unit measures radio flux. Crater on Moon and asteroid named after him. VLA renamed Karl G. Jansky VLA. Replica of his antenna at Green Bank Observatory. Monument at original Holmdel site. Jansky noise means cosmic static.