|
Gegenschein
Gegenschein (; ; ) or counterglow is a faintly bright spot in the night sky centered at the antisolar point. The backscatter of sunlight by interplanetary dust causes this optical phenomenon. Explanation Like zodiacal light, gegenschein is sunlight scattered by interplanetary dust. Most of this dust orbits the Sun near the ecliptic plane, with a possible concentration of particles centered at the point of the Earth–Sun system. Gegenschein is distinguished from zodiacal light by its high angle of reflection of the incident sunlight on the dust particles. It forms a slightly brighter elliptical spot of 8-10° across directly opposite the Sun within the dimmer band of zodiacal light and zodiac constellation. The intensity of the gegenschein is relatively enhanced because each dust particle is seen at full phase, having a difficult to measure apparent magnitude of +5 to +6, with a very low surface brightness in the +10 to +12 magnitude range. History It is commonly stat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gegenschein Above The VLT
Gegenschein (; ; ) or counterglow is a faintly bright spot in the night sky centered at the antisolar point. The backscatter of sunlight by interplanetary dust causes this optical phenomenon. Explanation Like zodiacal light, gegenschein is sunlight scattered by interplanetary dust. Most of this dust orbits the Sun near the ecliptic plane, with a possible concentration of particles centered at the point of the Earth–Sun system. Gegenschein is distinguished from zodiacal light by its high angle of reflection of the incident sunlight on the dust particles. It forms a slightly brighter elliptical spot of 8-10° across directly opposite the Sun within the dimmer band of zodiacal light and zodiac constellation. The intensity of the gegenschein is relatively enhanced because each dust particle is seen at full phase, having a difficult to measure apparent magnitude of +5 to +6, with a very low surface brightness in the +10 to +12 magnitude range. History It is commonly state ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zodiacal Light
The zodiacal light (also called false dawn when seen before sunrise) is a faint glow of diffuse sunlight scattered by interplanetary dust. Brighter around the Sun, it appears in a particularly dark night sky to extend from the Sun's direction in a roughly triangular shape along the zodiac, and appears with less intensity and visibility along the whole ecliptic as the zodiacal band. Zodiacal light spans the entire sky and contributes to the natural light of a clear and moonless night sky. A related phenomenon is ''gegenschein'' (or ''counterglow''), sunlight backscattered from the interplanetary dust, appearing directly opposite to the Sun as a faint but slightly brighter oval glow. Zodiacal light is very faint, often outshined and rendered invisible by moonlight or light pollution. The interplanetary dust in the Solar System forms a thick, pancake-shaped cloud called the zodiacal cloud which straddles the ecliptic plane. The particle sizes range from 10 to 300 micrometres, im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backscatter
In physics, backscatter (or backscattering) is the reflection of waves, particles, or signals back to the direction from which they came. It is usually a diffuse reflection due to scattering, as opposed to specular reflection as from a mirror, although specular backscattering can occur at normal incidence with a surface. Backscattering has important applications in astronomy, photography, and medical ultrasonography. The opposite effect is forward scatter, e.g. when a translucent material like a cloud diffuses sunlight, giving soft light. Backscatter of waves in physical space Backscattering can occur in quite different physical situations, where the incoming waves or particles are deflected from their original direction by different mechanisms: *Diffuse reflection from large particles and Mie scattering, causing alpenglow and gegenschein, and showing up in weather radar; * Inelastic collisions between electromagnetic waves and the transmitting medium (Brillouin scattering and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kordylewski Cloud
Kordylewski clouds are large concentrations of dust that exist at the and Lagrangian points of the Earth–Moon system. They were first reported by Polish astronomer Kazimierz Kordylewski in the 1960s, and confirmed to exist in October 2018. Discovery and observation Kordylewski began looking for a photometrically confirmable concentration of dust at the libration (Lagrangian) points in 1951. After a change in method suggested by Josef Witkowski, the clouds were first seen by Kordylewski in 1956. Between 6 March and 6 April 1961, he succeeded in photographing two bright patches near the Lagrange point. During the observation time, the patches hardly appeared to move relative to . The observations were taken from the mountain Kasprowy Wierch. In 1967, J. Wesley Simpson made observations of the clouds using the Kuiper Airborne Observatory. In October 2018, the existence of the Kordylewski clouds was reported to have been confirmed, even though, earlier, in 1992, the Japanes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodor Brorsen
Theodor Johan Christian Ambders Brorsen (29 July 1819 – 31 March 1895) was a Danish astronomer. He is best known for his discovery of five comets, including the lost periodic comet, 5D/Brorsen, and the periodic comet 23P/Brorsen-Metcalf. Life Theodor Johan Christian Ambders Brorsen was born in Nordborg on the island Als, ( South Jutland), as son of the captain Christian August Brorsen (1793-1840) and Annette Margrethe Gerhardine Schumacher (1788-1855). He got his three middle names after the maternal grandfather of his mother, the Nordborg counsel Johan Christian Ambders (1710-1795). After the amicable divorce of his parents in 1822, Brorsen grew up at his mother's. Her good financial circumstances allowed him to attend the school of the Moravians in Christiansfeld (1826-1829) and then, from 1830 to 1839, the Latin school in Flensburg. By request of his mother, Brorsen studied law in Kiel (1839), Berlin (1840), Heidelberg (1841), and again in Kiel (1842), until he de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Emerson Barnard
Edward Emerson Barnard (December 16, 1857 – February 6, 1923) was an American astronomer. He was commonly known as E. E. Barnard, and was recognized as a gifted observational astronomer. He is best known for his discovery of the high proper motion of Barnard's Star in 1916, which is named in his honor. Early life Barnard was born in Nashville, Tennessee, to Reuben Barnard and Elizabeth Jane Barnard (''née'' Haywood), and had one brother. His father died three months before his birth, so he grew up in an impoverished family and did not receive much in the way of formal education. His first interest was in the field of photography, and he became a photographer's assistant at the age of nine. He later developed an interest in astronomy. In 1876 he purchased a refractor telescope, and in 1881 he discovered his first comet, but failed to announce his discovery. He found his second comet later the same year and a third in 1882. While he was still working at a photography studio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antisolar Point
The antisolar point is the abstract point on the celestial sphere directly opposite the Sun from an observer's perspective. This means that the antisolar point lies above the horizon when the Sun is below it, and vice versa. On a sunny day, the antisolar point can be easily found; it is located within the shadow of the observer's head. Like the zenith and nadir, the antisolar point is not fixed in three-dimensional space, but is defined relative to the observer. Each observer has an antisolar point that moves as the observer changes position. The antisolar point forms the geometric center of several optical phenomena, including subhorizon haloes, rainbows, glories, the Brocken spectre, and heiligenschein. Occasionally, around sunset or sunrise, anticrepuscular rays appear to converge toward the antisolar point near the horizon. However, this is an optical illusion caused by perspective; in reality, the "rays" (i.e. bands of shadow) run near-parallel to each other. Also arou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplanetary Dust Cloud
The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar System. This system of particles has been studied for many years in order to understand its nature, origin, and relationship to larger bodies. There are several methods to obtain space dust measurement. In the Solar System, the interplanetary dust particles have a role in scattering sunlight and in emitting thermal radiation, which is the most prominent feature of the night sky's radiation, with wavelengths ranging 5–50 μm. The particle sizes of grains characterizing the infrared emission near Earth's orbit typically range 10–100 μm. Microscopic impact craters on lunar rocks returned by the Apollo Program revealed the size distribution of cosmic dust particles bombarding the lunar surface. The ’’Grün’’ distribution of interpl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplanetary Dust Cloud
The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar System. This system of particles has been studied for many years in order to understand its nature, origin, and relationship to larger bodies. There are several methods to obtain space dust measurement. In the Solar System, the interplanetary dust particles have a role in scattering sunlight and in emitting thermal radiation, which is the most prominent feature of the night sky's radiation, with wavelengths ranging 5–50 μm. The particle sizes of grains characterizing the infrared emission near Earth's orbit typically range 10–100 μm. Microscopic impact craters on lunar rocks returned by the Apollo Program revealed the size distribution of cosmic dust particles bombarding the lunar surface. The ’’Grün’’ distribution of interpl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interplanetary Dust
The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar System. This system of particles has been studied for many years in order to understand its nature, origin, and relationship to larger bodies. There are several methods to obtain space dust measurement. In the Solar System, the interplanetary dust particles have a role in scattering sunlight and in emitting thermal radiation, which is the most prominent feature of the night sky's radiation, with wavelengths ranging 5–50 μm. The particle sizes of grains characterizing the infrared emission near Earth's orbit typically range 10–100 μm. Microscopic impact craters on lunar rocks returned by the Apollo Program revealed the size distribution of cosmic dust particles bombarding the lunar surface. The ’’Grün’’ distribution of interplan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antisolar Point
The antisolar point is the abstract point on the celestial sphere directly opposite the Sun from an observer's perspective. This means that the antisolar point lies above the horizon when the Sun is below it, and vice versa. On a sunny day, the antisolar point can be easily found; it is located within the shadow of the observer's head. Like the zenith and nadir, the antisolar point is not fixed in three-dimensional space, but is defined relative to the observer. Each observer has an antisolar point that moves as the observer changes position. The antisolar point forms the geometric center of several optical phenomena, including subhorizon haloes, rainbows, glories, the Brocken spectre, and heiligenschein. Occasionally, around sunset or sunrise, anticrepuscular rays appear to converge toward the antisolar point near the horizon. However, this is an optical illusion caused by perspective; in reality, the "rays" (i.e. bands of shadow) run near-parallel to each other. Also arou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heiligenschein
(; ) is an optical phenomenon in which a bright spot appears around the shadow of the viewer's head in the presence of dew. In photogrammetry and remote sensing, it is more commonly known as the hotspot. It is also occasionally known as Cellini's halo after the Italian artist and writer Benvenuto Cellini (15001571), who described the phenomenon in his memoirs in 1562. Nearly spherical dew droplets act as lenses to focus the light onto the surface behind them. When this light scatters or reflects off that surface, the same lens re-focuses that light into the direction from which it came. This configuration is sometimes called a cat's eye retroreflector. Any retroreflective surface is brightest around the antisolar point. Opposition surge by other particles than water and the glory in water vapour are similar effects caused by different mechanisms. See also * Aureole effect * Brocken spectre, the magnified shadow of an observer cast upon the upper surfaces of clouds opposite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
