cosmic noise

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cosmic noise

(Jansky noise) See antenna temperature.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Cosmic Noise


the electrical fluctuations in a receiving antenna that are due to the radio radiation of the sun, the stars, the planets, interstellar media, and other matter.

Regardless of its origin, cosmic noise manifests itself in radio reception in the same manner as thermal noise. Its intensity is defined in terms of the brightness temperature of the sky, which is the equivalent temperature of the hypothetical celestial sphere that envelops the antenna and that has the properties of a black body. The heat-radiation levels of the hypothetical sphere and of the real sources of cosmic noise must be equal in all directions to satisfy the criterion of equivalence. Sky temperature decreases rapidly with the decrease of wavelength λ. Specifically, when detected by an antenna with a broad directivity diagram, mean cosmic noise levels—the noise background of the sky—decrease with λ as λ–24. When λ ≈ 5 cm, for example, cosmic-noise temperature is approximately 15°K.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

cosmic noise

[′käz·mik ′nȯiz]
Radio static caused by a phenomenon outside the earth's atmosphere, such as sunspots.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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