The site in Chile of the European Southern Observatory’s Very Large Telescope VLT. It is situated in the Atacama desert, 120 km 75 miles south of Antofagasta, at an altitude of 2,632 metres 8,500 feet.

An asteroid, comet or other body of which a meteorite is a fragment.

An alternative name for a mock Sun or sundog.

Observatoire de Paris.

An Australian radio astronomy observatory located 20 kilometres 12 miles north of Parkes, New South Wales. The instrument is an altazimuth mounted, prime-focus, 64-metre 210-foot single dish. It was commissioned in 1961 and operated by the Commonwealth Scientific and Industrial Research Organization CSIRO Division of Radiophysics as the Australian National Radio Astronomy Observatory. In 1988 it became a unit of the Australia Telescope. It can serve as a stand-alone telescope or as a member of a long-baseline array. The Parkes dish was the first to be built in the southern hemisphere. It was used for the identification of the first quasar in 1963, and to discover many interstellar molecules and over half the known pulsars. It has also been used as an additional element in the Deep Space Network for tracking spacecraft, for example during the Voyager 2 encounters with Uranus and Neptune and the Giotto mission to Halley’s Comet.

A unit of distance used in professional astronomy. It is defined as the distance at which an object would have an annual parallax of one arc second. It is equivalent to 3.0857 × 10 to the power of 13 kilometres, 3.2616 light years or 206,265 astronomical units. Multiples in common use are the kiloparsec kpc, 1,000 parsecs and the megaparsec Mpc, 1,000,000 parsecs.

The limit of the visible universe, within which light has had time to reach us since the expansion of the universe began.

One of the small outer satellites of Jupiter number VIII, discovered in 1908 by P. J. Melotte.

A shallow crater with a scalloped or complex edge.

Asteroid 451, diameter 230 km, discovered by A. Charlois in 1899.

Australia Telescope.

An optical design for a reflecting telescope that has an exceptionally wide field of view with good definition. It uses a paraboloid primary of focal ratio f/4 or less, a convex spherical secondary mirror, and a concave spherical third mirror with curvature equal but opposite to that of the secondary. It was devised by the French optician Maurice Paul in 1935 and discovered independently by James Baker in about 1945. See also: Willstrop telescope.

A southern constellation introduced in the 1603 star atlas of Johann Bayer. It contains one first magnitude star, sometimes itself called Peacock.

One of the three giant shield volcanoes of the Tharsis Ridge on Mars. It is about 400 kilometres 250 miles in diameter and rises to a height of 27 kilometres 17 miles, 17 kilometres above the level of the surrounding ridge.

Abbreviation for parsec.