Kordylewski cloud

Diagram showing the Lagrangian points of the Earth–Moon system. Kordylewski clouds exist in the regions of L4 and L5.

Kordylewski clouds are large concentrations of dust that exist at the L4 and L5 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

Kordylewski began looking for a photometrically confirmable concentration of dust at the libration (Lagrangian) points in 1951.[4][5]

After a change in method suggested by Josef Witkowski, 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 L5 Lagrange point.[5] During the observation time, the patches hardly appeared to move relative to L5.[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 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.[6][7]