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Related to gegenschein: zodiacal light, zoanthropy, Zodiacal band


gegenschein (gāˈgənshīnˌ) or counterglow, a slight brightening of the night sky in the region of the zodiac directly opposite the sun, i.e., 180° from the sun. Discovered by the Danish astronomer Theodor Brersen in 1854, it is caused by reflection of sunlight by interplanetary dust particles that lie in the plane of the solar system. The brightening is relatively faint and is obscured by moonlight and, in the weeks on either side of the solstices, by the Milky Way. The gegenschein is one of several sky glows, as are zodiacal light and airglow.
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(gay -gĕn-shÿn) (counterglow) A very faint patch of light that can be seen on a clear moonless night on the ecliptic at a point 180° from the Sun's position at the time of observation. It is part of the zodiacal light.
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 It might be outdated or ideologically biased.



(counterglow), a faintly glowing, low-contrast, diffuse spot located in the night sky in the area opposite the sun. The gegenschein is joined to the cones of the zodiacal light by what is called the zodiacal band, a very faint luminescence that extends along the ecliptic in the form of a band about 10° wide. The brightness of the gegenschein exceeds the brightness of the background of the night sky by just 10–15 percent, so it can only be seen on dark, moonless nights when the atmosphere is very clear and the area of the sky opposite the sun is far from the horizon and the Milky Way (in the spring and autumn).

The gegenschein was first observed by A. Humboldt in the period 1799–1803. It is now studied by photometric and spectographic methods, and important results have been obtained from observations made by satellites and space probes. Its diameter is about 20°, with brightness decreasing from the center toward the periphery. Fraunhofer lines found in the solar spectrum have been detected in the gegenschein spectrum. It has been established that the gegenschein is caused by the scattering of solar light by dust particles in interplanetary space, but the spatial distribution of the mass of dust that causes the gegenschein has been studied very little.

Various hypotheses have been proposed to explain the nature of the gegenschein. The most important are the hypothesis of a circumsolar dust cloud; the hypothesis of the accumulation of dust particles at the antisolar libration point of the sun-earth system—a point that is located at a distance of 1.5 million km from the earth; and the hypothesis that the earth has tails of dust and gas, similar to the tails of comets. Measurements taken from the American Pioneer 10 spacecraft when it was 5–8 million km from the earth and 1.011 astronomical units from the sun provide evidence, however, that the gegenschein is unrelated to the earth but is caused by the scattering of solar light by dust particles located outside the earth’s orbit in interplanetary space.


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


A round or elongated, faint, ill-defined spot of light in the sky at a point 180° from the sun. Also known as counterglow; zodiacal counterglow.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
But the true discoverer of the gegenschein will probably never be known.
The word gegenschein is German for "counterglow." It refers to an elliptical enhancement and enlargement of the narrow corridor of light known as the zodiacal band, the very dim and narrow glow that follows the ecliptic through the zodiacal constellations.
Early theories of the gegenschein bordered on the fantastic.
For the zodiacal light, the zodiacal band, and the gegenschein are glows created by sunlight that is reflected and scattered by dust particles, typically of submillimeter or micron size, lying in or near the plane of the inner solar system.
The gegenschein is a second enhancement, or backscattering effect, in which the sunlight changes direction by almost 180[degrees] in the outlying parts of the same dust cloud.
In the case of the gegenschein, we don't see the Earth's shadow in the middle of the glow because most of the backscattering dust lies far beyond the immediate vicinity of our planet.
From April through early September each year the antisolar point is too low in the sky for the gegenschein to be seen well from midnorthern latitudes.
But no matter on what date you look, the full oval of the gegenschein crosses the meridian and reaches its high point around midnight.
Only later did I realize that this midnight glow was near the antisolar point and must be the gegenschein. I wasn't even looking for it, and that's why I am so convinced that the ancients, too, must have witnessed this glow.
The gegenschein is usually a soft, oval glow whose brightest parts measure about 10[degrees] to 15[degrees] long (like a fist held at arm's length).
"When first seen in the fall," he wrote in the Astronomical Journal, "the Gegenschein is large and roundish, and does not seem to be connected to any zodiacal bands.