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The zodiacal light in the eastern sky before the beginning of morning twilight. The planet Venus and the open cluster M44 are also visible in this photograph.
The zodiacal light in the eastern sky before the beginning of morning twilight. Twilight is the time before Sunrise, called Dawn, and the time after Sunset, called Dusk. The planet Venus and the open cluster M44 are also visible in this photograph.

The zodiacal light is a faint, roughly triangular, whitish glow seen in the night sky which appears to extend up from the vicinity of the sun along the ecliptic or zodiac. The Sun (Sol is the Star at the center of the Solar System. The ecliptic is the apparent path that the Sun traces out in the sky during the year Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic In mid-northern latitudes, the zodiacal light is best observed in the western sky in the spring after the evening twilight has completely disappeared, or in the eastern sky in the autumn just before the morning twilight appears. Spring is one of the four Temperate Seasons Spring marks the transition from Winter into Summer. Twilight is the time before Sunrise, called Dawn, and the time after Sunset, called Dusk. Autumn (also known as fall in North American English) is one of the four Temperate Seasons Autumn marks the transition from Summer It is so faint that it is completely masked by either moonlight or light pollution. Moonlight is the light that comes to Earth from the Moon. This light does not originate from the Moon but is actually reflected Sunlight. Light pollution, also known as photopollution or luminous pollution, is excess or obtrusive Light created mainly by Humans Among other effects The zodiacal light decreases in intensity with distance from the Sun, but on very dark nights it has been observed in a band completely around the ecliptic. The ecliptic is the apparent path that the Sun traces out in the sky during the year In fact, the zodiacal light covers the entire sky, being responsible for 60% of the total skylight on a moonless night. There is also a very faint, but still slightly increased, oval glow directly opposite the Sun which is known as the gegenschein. Gegenschein ( very roughy like GAY-guhn-shine German for "counter shine" is a faint brightening of the night sky in the region of the Antisolar

This phenomenon was first investigated by the astronomer Giovanni Domenico Cassini in 1683 and first explained by Nicolas Fatio de Duillier in 1684. Giovanni Domenico Cassini ( June 8, 1625 &ndash September 14, 1712) was an Italian Mathematician, Astronomer Nicolas Fatio de Duillier (alternative names are Facio or Faccio) ( 26 February 1664 - 12 May 1753) was a Swiss

Contents

Formation

A green and red Orionid meteor striking the sky below Milky Way and to the right of Venus. Zodiacal light is also seen at the image
A green and red Orionid meteor striking the sky below Milky Way and to the right of Venus. The Orionids are an annual meteor shower, named after their radiant which occurs in the Constellation Orion. The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Γαλαξίας (Galaxias sometimes referred to simply The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University Zodiacal light is also seen at the image

The zodiacal light is produced by sunlight reflecting off dust particles which are present in the solar system and known as cosmic dust. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. Consequently, its spectrum is the same as the solar spectrum. Spectroscopy was originally the study of the interaction between Radiation and Matter as a function of Wavelength (λ The Sun (Sol is the Star at the center of the Solar System. The material producing the zodiacal light is located in a lens-shaped volume of space centered on the sun and extending well out beyond the orbit of Earth. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star This material is known as the interplanetary dust cloud. The interplanetary dust cloud is Cosmic dust (small particles floating in space which pervade the space between Planets in the Solar System and in Since most of the material is located near the plane of the solar system, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth's moon, each particle would be 8 km from its neighbors. The albedo of an object is the extent to which it diffusely reflects light from the sun The gegenschein may be due to the fact that particles directly opposite the sun as seen from Earth would be in full phase. Lunar phase (or Moon phase refers to the appearance of the illuminated portion of the Moon as seen by an observer usually on Earth

The Poynting-Robertson effect causes the particles to spiral slowly into the Sun, thus requiring a continuous source of new particles to maintain the zodiacal cloud. The Poynting-Robertson effect, also known as Poynting-Robertson drag, named after John Henry Poynting and Howard Percy Robertson, is a process by which Cometary dust and dust generated by collisions among the asteroids are believed to be mostly responsible for the maintenance of the dust cloud producing the zodiacal light and the gegenschein. A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but Gegenschein ( very roughy like GAY-guhn-shine German for "counter shine" is a faint brightening of the night sky in the region of the Antisolar In recent years, observations by a variety of spacecraft have shown significant structure in the zodiacal light including dust bands associated with debris from particular asteroid families and several cometary trails. Minor planet is a term used since the 19th century to describe objects such as Asteroids that are in Orbit around the Sun but are not Planets

Historical explanations

Previously, it was believed that zodiacal light was just the atmosphere of the sun. The Sun (Sol is the Star at the center of the Solar System. According to the 1728 Cyclopaedia:

"The zodiacal light is nothing but the solar atmosphere, a rare and subtile fluid, either luminous by itself, or made so by the rays of the sun surrounding its globe; but in a greater quantity, and more extensively, about its equator, than any other. Cyclopaedia or A Universal Dictionary of Arts and Sciences ( folio, 2 vols "

Importance to Islam

The Prophet Muhammed is known to have described zodiacal light in reference to the timing of the five daily prayers, calling it the "false dawn," or "al Fajr al Khaadib. Ṣalāt ( Arabic: صلاة‎, pl ṣalawāt, Qur'anic Arabic: صلوة ṣalawah) (also munz in Pashto and " Muslim oral tradition preserves numerous sayings, or hadith, in which Muhammed describes the difference between the light of false dawn, appearing in the sky long after sunset, and the light of the first band of horizontal light at sunrise, the true dawn. Hadith ( ar الحديث, pl aḥadīth; lit. "narrative" are oral Traditions relating to the words and deeds of the Islamic Practitioners of Islam use the Prophet's descriptions of zodiacal light to avoid errors in determining the timing of daily prayers. For other meanings including people named 'Islam' see Islam (disambiguation.

Such practical descriptions and applications of astronomical observations were vital to the golden age of Islamic astronomy.

See also

References

External links

Dictionary

zodiacal light

-noun

  1. (astronomy) soft glow of white light extending upward from the horizon along the ecliptic, particularly in the tropics.
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