BornPoznan, Poland, 11 October 1903
DiedCracow, Poland, 11 March 1981
A versatile and prolific observer, Kazimierz Kordylewski discovered the “dust clouds” accompanying Lagrangian points L4 and L5 along the Earth’s orbit. Son of Wladyslaw and Franciszka (née Woroch) Kordylewski, he first attended Poznan University (1922–1924), after which he became an assistant at the Cracow Observatory (1924–1934) and later an adjunct instructor. Kordylewski received his Ph.D. at Jagiellonian University in Cracow (1932). He married Jadwiga Pojak in 1929; the couple had four children.
An accomplished mathematician, Kordylewski calculated the orbits of many comets and minor planets, although his principal work involved the photoelectric photometry of variable stars and the cinematography of solar eclipses. He discovered the nova T Corvi in 1926. Between 1939 and 1951, Kordylewski directed the scientific instruments section of the National Astronomical Copernicus Institute, at Cracow, as well as the institute itself. After 1958, he was chief of the observing station for artificial satellites, and edited the Eclipsing Binaries Circulars (1960–). Kordylewski was president of the Cracow branch of the Polish Astronomical Society (1956–).
In 1951, Kordylewski began to hunt for small “Trojan” satellites of the Earth at the L4 and L5 libration points, located 60° ahead of and behind the Moon in its orbit. His initial visual search with a 30-cm refractor proved unsuccessful. Then in 1956, professor Josef Witkowski suggested that Kordylewski stop looking for solid bodies and search instead for faint luminous patches of dust. Following this advice, when observing from the Skalnaté Pleso Observatory in Czechoslovakia’s Tatras Mountains in 1956, Kordylewski managed to glimpse with his naked eye an exceedingly faint, diffuse patch of light subtending an apparent angle of 2° at one of the Lagrangian points. He estimated its brightness as only half that of the notoriously difficult Gegenschein. In March and April of 1961, Kordylewski succeeded in capturing images of these transient clouds on film and subjected them to isodensitometry measurements.
Although they were observed as early as January 1964 by the American amateur astronomer John Wesley Simpson (1914–1977) and his colleagues in the Santa Cruz Mountains of California, the reality of the Kordylewski clouds was debated until 1975, when J. R. Roach announced their detection using data acquired over a 15-month period by the Orbiting Solar Observatory 6 [OSO-6] spacecraft. The clouds were subsequently photographed on many occasions by Maciej Winiarski, using batteries of wide-angle cameras at a dark site in Poland’s Bieszczady Mountains. Thus, Kordylewski is remembered as the discoverer of these ephemeral natural satellites of the Earth, the culmination of a century-long hunt for a “second Moon.”