Artist's illustration of the Kordylewski cloud in the night sky (with its brightness greatly enhanced) at the time of the observations.
Credit: G. Horváth
Kordylewski clouds are large concentrations of dust that exist at the L and L Lagrangian points of the Earth–Moon system.[1][2][3] They were first reported by Polish astronomer Kazimierz Kordylewski in the 1960s, and confirmed to exist in October 2018.[1][2][3]
Discovery and observation
The existence of a photometrically confirmable concentration of dust at the libration points was predicted by Josef Witkowski in 1956 (1951?).[4][5]
The clouds were first seen by Kordylewski in 1956.[6] Between 6 March and 6 April 1961, he succeeded in photographing two bright patches near the L libration point.[5] During the observation time, the patches hardly appeared to move relative to L.[5] The observations were taken from the mountain Kasprowy Wierch.[5]
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,[1][2][3] even though, earlier, in 2009, the Japanese Hiten space probe, which passed through the libration points to detect trapped dust particles, did not find an obvious increase in dust levels above the density in surrounding space.[6][7]
Appearance
The Kordylewski clouds are a very faint phenomenon, comparable to the brightness of the gegenschein.[8]
They are very difficult to observe from Earth[6] but may be visible to the unaided eye in an exceptionally dark and clear night sky.[8] Most claimed observations have been made from deserts, at sea, or from mountains.[8] The clouds appear somewhat redder than the gegenschein, indicating that they may be made of a different kind of particle.[6]
The Kordylewski clouds are located near the L and L Lagrange points of the Earth–Moon system.[6] They are about 6 degrees in angular diameter.[6] The clouds can drift up to 6 to 10 degrees from those points.[8] Other observations suggest they move around the libration points in ellipses of about 6 by 2 degrees.[6]
Explanation:
Like the zodiacal light, the gegenschein is sunlight scattered by interplanetary dust.
Most of this dust is orbiting the Sun in about the ecliptic plane, with a possible concentration of particles at the L2 Earth–Sun Lagrangian point.[1]
It is distinguished from zodiacal light by its high angle of reflection of the incident sunlight on the dust particles.
It forms a slightly more luminous, oval glow directly opposite the Sun within the band of luminous zodiacal light.
The intensity of the gegenschein is relatively enhanced, because each dust particle is seen in full phase.[2]
History
The gegenschein was first described by the French Jesuit astronomer and professor Esprit Pezenas (fr) (1692–1776) in 1730.
Further observations were made by the German explorer Alexander von Humboldt during his South American journey from 1799 to 1803. It was also Humboldt who gave the phenomenon its German name Gegenschein.[3]
The Danish astronomer Theodor Brorsen published the first thorough investigations of the gegenschein in 1854,[4] stating that Pezenas was the first to see it. T. W. Backhouse discovered it independently in 1876, as did Edward Emerson Barnard in 1882.[5]
In modern times, the gegenschein is not visible in most inhabited regions of the world due to light pollution.
Sunlight scattered by interplanetary dust causes this phenomenon. Zodiacal light is best seen during twilight after sunset in spring and before sunrise in autumn, when the zodiac is at a steep angle to the horizon.
However, the glow is so faint that moonlight and/or light pollution outshine it, rendering it invisible.
The brightness of zodiacal light decreases with distance from the Sun. In naturally dark night skies, the glow is visible as a band along the entire zodiac, completely straddling the ecliptic.
In fact, zodiacal light spans the entire sky and largely[5] contributes to the total natural light in a clear and moonless night sky.
Another phenomenon – a faint but slightly brighter oval glow – directly opposite of the Sun’s direction is the gegenschein, which is caused by backscattered sunlight.
The interplanetary dust in the Solar System collectively forms a thick, pancake-shaped cloud called the zodiacal cloud, which straddles the ecliptic plane.
The particle sizes range between 10 and 300 micrometres, most with a mass around 150 micrograms.[6]
IOW, Earth has a ring....................
Interesting!
How long before somebody stupid calls it “space pollution”?
Space dust bunny ping!
