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Cygnus A
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Cygnus A Cygnus A Radiograph produced by the Very Large Array of the double-lobed radio galaxy Cygnus A at 6-cm wavelength. The radio jet extending from the core to the northwest lobe (right) is readily seen, but evidence for a counterjet to the southeast lobe (left) is marginal.
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Cygnus A
Cygnus A 5-GHz radio image of Cygnus A.

Cygnus A

astronomy
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Cygnus A, most powerful cosmic source of radio waves known, lying in the northern constellation Cygnus about 500,000,000 light-years (4.8 × 1021 km) from Earth. It has the appearance of a double galaxy. For a time it was thought to be two galaxies in collision, but the energy output is too large to be accounted for in that way. Radio energy is emitted from Cygnus A at an estimated 1045 ergs per second, more than 1011 times the rate at which energy of all kinds is emitted by the Sun. The source of the energy of Cygnus A remains undetermined.

This article was most recently revised and updated by Amy Tikkanen.