page_title: Atmospheric noise
section_title: History
hierarchical_section_title: Atmospheric noise / History
caption_attribution_description: English: Full-size replica of the first radio telescope, built by Karl Jansky and now at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia Русский: Точная копия радиотелескопа Карла Янского в натуральную величину. Национальная радиоастрономическая обсерватория (NRAO), Грин-Бэнк, Западная Виргиния, США.
context_page_description: Atmospheric noise is radio noise caused by natural atmospheric processes, primarily lightning discharges in thunderstorms. On a worldwide scale, there are about 40 lightning flashes per second – ≈3.5 million lightning discharges per day.
context_section_description: In 1925, AT&T Bell Laboratories started investigating the sources of noise in its transatlantic radio telephone service.
  Karl Jansky, a 22-year-old researcher, undertook the task. By 1930, a radio antenna for a wavelength of 14.6 meters was constructed in Holmdel, NJ, to measure the noise in all directions. Jansky recognized three sources of radio noise. The first (and strongest) source was local thunderstorms. The second source was weaker noise from more distant thunderstorms. The third source was a still weaker hiss that turned out to be galactic noise from the center of the Milky Way. Jansky's research made him the father of radio astronomy.
caption: Replica of Jansky's radio telescope, now at the National Radio Astronomy Observatory. 38°25′54″N 79°48′59″W﻿ / ﻿38.431659°N 79.816253°W﻿ / 38.431659; -79.816253
exif: {}