Belt of Venus

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.

ALMA and Chajnantor at twilight. Lying between the two groups of antennas are the Earth's shadow and Belt of Venus phenomena.^[1]

Gallery

• 

  Full moon rising near Linz, Austria. Observed through the Belt of Venus.

• 

  Belt of Venus at 42,000 feet (13,000 m)

• 

  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.

See also

• Anticrepuscular rays
• Atmospheric refraction
• Blue hour
• Earth's shadow
• Golden hour or Magic hour

References

• Naylor, John (2002). Out of the blue : a 24-hour skywatcher's guide. Cambridge: Cambridge University Press. p. 72. ISBN 0-521-80925-8. 

External links

• APOD entry
• Further APOD entry (scroll to right of image for best view)

Parts of a day Dawn–Twilight–Sunrise Morning Daytime Evening Sunset–Twilight–Dusk Night Related articles: Belt of Venus Blue hour Golden hour Terminator Daylight Forenoon Noon Afternoon Midnight Midnight sun

Wikimedia Commons has media related to Category:Belt of Venus.