Belt of Venus
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The Belt of Venus or Venus's Girdle is an atmospheric phenomenon seen at sunrise and sunset. Shortly after sunset or shortly before sunrise, the observer is, or is very nearly, surrounded by a pinkish glow (or anti-twilight arch) that extends roughly 10°–20° above the horizon. It is similar to alpenglow as they both are caused by backscattering of reddened sunlight. The only difference is that alpenglow is characterized by afterglow and is a red horizontal band visible just after sunset or before sunrise due to direct illumination of clouds and aerosols low in the atmosphere, whereas the Belt of Venus is a rosy pinkish arch visible long after sunset or long before sunrise, caused by backscattering of refracted sunlight due to fine dust particles high in the atmosphere. In a way, the Belt of Venus is a true alpenglow visible at twilight near the anti-solar point. Often, the glow is separated from the horizon by a dark layer, the Earth's shadow or "dark segment." The arch's light pink color is due to backscattering of reddened light from the rising or setting Sun. A very similar effect can be seen during a total solar eclipse. The zodiacal light, which is caused by reflection of sunlight from the interplanetary dust in the solar system, is also a similar phenomenon.
Full moon rising near Linz, Austria. Observed through the Belt of Venus.
Moon seen through the Belt of Venus. Note that the full Moon is near the centre of the field of view, which means that the Sun must be behind the camera, just below the horizon.
Belt of Venus photographed over a lake in Seattle, Washington.
- "ALMA and Chajnantor at Twilight". ESO Picture of the Week. Retrieved 18 January 2014.
- Naylor, John (2002). Out of the blue : a 24-hour skywatcher's guide. Cambridge: Cambridge University Press. p. 72. ISBN 0-521-80925-8.
- NASA Astronomy Picture of the Day: The Belt of Venus over the Valley of the Moon (23 July 2006)
- NASA Astronomy Picture of the Day: The Belt of Venus Over Mercedes, Argentina (scroll to right of image for best view) (7 February 2012)
- Shadow of Earth, Belt of Venus as seen over Half Dome, Yosemite National Park, displayed in an interactive panorama. Scroll to the very bottom of the post to view, after all other Yosemite panoramas.
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