Atlas (astronomy)

Atlas in astronomy, one of the named moons, or natural satellites, of Saturn . Also known as Saturn XV (or S15), Atlas is a small, irregularly shaped (nonspherical) body measuring about 25 mi (40 km) by 12.5 mi (20 km); it orbits Saturn at a mean distance of 85,544 mi (137,670 km), and has an orbital period of 0.6019 earth days—the rotational period is unknown but is assumed to be the same as the orbital period. Atlas was discovered by Richard J. Terrile in 1980 from photographs taken by Voyager 1 during its flyby of Saturn. Atlas is probably a shepherd satellite (a moon that limits the extent of a planetary ring through gravitational forces) of Saturn's A ring.

ATLAS (ˈætləs) Astronomy airborne tunable laser absorption spectrometer
• (USA) Argonne tandem-linac accelerator system

Kuiper, G. P. (1905–73) The important contributions made to planetary astronomy by G. P. Kuiper were also of great significance for the geological sciences. Kuiper was born in the Netherlands and studied astronomy at the University of Leiden. In 1933 he moved to the United States and was subsequently known as Gerard Peter rather than as Gerrit Pieter Kuiper. In America he worked first at the Lick Observatory in California, and subsequently at Harvard, Chicago, and the University of Arizona, where he established the multidisciplinary Lunar and Planetary Laboratory.

It was Kuiper who first discovered (using spectroscopic methods) that Titan, Saturn's largest moon, has an atmosphere. Among Earth scientists he is perhaps best known for his theory of the origin of the Solar System, in which he postulated a ‘reservoir’ of icy planetismals beyond the orbit of Pluto. His research provided evidence in support of the impact theory of crater formation.

Kuiper studied the surface of the Moon and produced lunar atlases. He was also the editor or co-editor of substantial publications on the atmospheres of the Earth and the planets, the Solar System, and stars and stellar systems. The Kuiper Belt is named after him.

D. L. Dineley