Kordylewski cloud
Kordylewski clouds, also named ghost moons,Template:Cn are concentrations of dust that exist at the Template:L4 and Template:L5 Lagrangian points of the Earth–Moon system.<ref name="TWC-20181105">Template:Cite news</ref><ref name="EA-20181026">Template:Cite news</ref><ref name="MN-RAS-20181111">Template:Cite journal</ref><ref name="MN-RAS-20190101">Template:Cite journal</ref> They were first reported by Polish astronomer Kazimierz Kordylewski in the 1960s, and confirmed to exist by the Royal Astronomical Society in October 2018.<ref name="EA-20181026" /><ref name="MN-RAS-20181111" /><ref name="MN-RAS-20190101" />
Discovery and observationEdit
Kordylewski began looking for a photometrically confirmable concentration of dust at the libration (Lagrangian) points in 1951.<ref name="BEA">Template:Cite book</ref><ref name="Kordylewski">Template:Cite journal</ref>
After a change in method suggested by Josef Witkowski, the clouds were first seen by Kordylewski in 1956.<ref name=Laufer>Template:Cite conference</ref> Between 6 March and 6 April 1961, he succeeded in photographing two bright patches near the Template:L5 Lagrange point. During the observation time, the patches hardly appeared to move relative to Template:L5. The observations were taken from the mountain Kasprowy Wierch.<ref name=Kordylewski/>
In 1967, J. Wesley Simpson made observations of the clouds using the Kuiper Airborne Observatory.Template:Sfn
In October 2018, the existence of the Kordylewski clouds was reported to have been confirmed by the Royal Astronomical Society,<ref name="EA-20181026" /><ref name="MN-RAS-20181111" /><ref name="MN-RAS-20190101" /> even though, earlier, in 1992, the Japanese Hiten space probe, which passed through the Lagrange points to detect trapped dust particles, did not find an obvious increase in dust levels above the density in surrounding space.<ref name=Laufer/><ref name=NASAHiten> {{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Hiten's failure to find the Kordylewski clouds does not rule out their existence, since the probe revolved around each Lagrange point for only one loop and could have missed the clouds.<ref name=Wang>Template:Cite journal</ref>
The decisive factor and change of methodology that has led to the unambiguous confirmation of the existence of these extremely faint and elusive celestial objects was using polarimetry, i.e. detecting them by their polarization patterns, not (primarily) by their brightness.<ref name="EA-20181026" />
AppearanceEdit
The Kordylewski clouds are a very faint phenomenon, comparable to the brightness of the gegenschein.<ref name="Covington">Template:Cite book</ref> They are very difficult to observe from Earth<ref name=Laufer/> but may be visible to the unaided eye in an exceptionally dark and clear night sky. Most claimed observations have been made from deserts, at sea, or from mountains.<ref name=Covington/> The clouds appear somewhat redder than the gegenschein, indicating that they may be made of a different kind of particle.<ref name=Laufer/>
PositionEdit
The Kordylewski clouds are located near the Template:L4 and Template:L5 Lagrange points of the Earth–Moon system. They are about 6 degrees in angular diameter.<ref name=Laufer/> The clouds can drift up to 6 to 10 degrees from those points.<ref name=Covington/> Other observations suggest they move around the Lagrange points in ellipses of about 6 by 2 degrees.<ref name=Laufer/>
See alsoEdit
NotesEdit
ReferencesEdit
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- Hypothetical Planets
- A Search for Objects near the Earth–Moon Lagrangian Points, by Francisco Valdes and Robert A. Freitas Jr., did not find any objects at the Earth–Moon or Earth–Sun lagrange points, but this survey was not sensitive to diffuse clouds.
- Template:Cite journal
- One of Earth’s shimmering dust clouds has been spotted at last