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(Comet 1957 III), one of the most interesting comets of the 20th century; discovered Nov. 8, 1956, by S. Arend and G. Roland of Belgium. In April 1957, near the perihelion, Comet Arend-Roland attained the brightness of a star of the first stellar magnitude; the diameter of its head reached 300,000 km, the main tail was 45 million km long, and the bright secondary tail was 50–60 million km long. Numerous astrophysical observations of Comet Arend-Roland indicated a probable dust-particle structure of the secondary tail and a main tail structure of mixed dust and gaseous matter. The latter displayed interesting ray structures and cloud formations which accelerated rapidly. The comet could be observed by telescope until April 1958.