Radio astronomy

Article By:

Kellermann, Kenneth National Radio Astronomy Observatory, Charlottesville, Virginia.

Last reviewed:February 2019

DOI:https://doi.org/10.1036/1097-8542.567500

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• Radio astronomy, published February 2014:Download PDF Get Adobe Acrobat Reader

The study of celestial bodies by examination of the energy they emit at radio frequencies. Radio astronomy observations cover the entire radio spectrum from less than 1 mm, where the cosmic signals become heavily attenuated by the atmosphere, to wavelengths of tens of meters, beyond which the incoming signals are attenuated by the ionosphere. However, radio waves between about 1 cm and 1 m in wavelength not only get through the Earth's atmosphere and ionosphere with little distortion, they also penetrate much of the gas and dust in space as well as the clouds of planetary atmospheres. Radio astronomy can therefore sometimes give a much clearer picture of stars and galaxies than is possible by means of conventional observation using visible light. Sophisticated antennas equipped with very sensitive radio receivers that are used to detect cosmic radio emission are referred to as radio telescopes (Fig. 1). See also: Atmosphere; Earth; Galaxy; Ionosphere; Radio telescope; Star; Wavelength

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