A range of mountains on the Moon, lying between the Mare Frigoris and the Mare Imbrium.

Abbreviation for Apollo Lunar Science Experiment Package, experimental set-ups that were deployed on the Moon by astronauts during the manned Apollo programme 1969-72. One was left by every mission except the first. Each automated laboratory was powered by a small nuclear generator. The packages included seismometers to measure moonquakes and experiments to measure the solar wind, detect any trace atmosphere and measure the heat flow from the Moon’s interior. All the experiments were turned off in 1978.

The brightest star in the constellation Aquila. The Arabic name means the flying eagle. It is an A star of magnitude 0.8 and one of the closest of the brighter stars at a distance of 17 light years.

English name for the constellation Ara.

A form of telescope mounting in which the two independent rotation axes allow movement of the instrument in altitude and azimuth. It is the simplest type of telescope mounting but it is necessary to move the telescope about both axes simultaneously in order to track the motion of celestial objects across the sky. For that reason it is not suitable for small, motor-driven telescopes. However, the ability to control the motion of a large telescope by computer has in recent years led to a revival in the popularity of simple altazimuth mountings for new professional instruments. See also: Dobsonian telescope, equatorial mounting.

The measurement of height, including techniques such as the determination of the height of planetary features by means of radar.

The angular distance above an observer’s horizon. Altitude is measured in degrees, 0° being at the horizon and 90° being at the observer’s zenith. An object below the observer’s horizon has a negative altitude. Altitude is one coordinate in the horizontal coordinate system. Azimuth is the other coordinate.

stars which show an excess of most heavy elements, but are strangely deficient in some, mostly calcium and scandium. These stars must rotate very slowly to avoid stirring up the atmosphere; the braking affect of tidal forces supplied by a companion star seems to have allowed them to achieve this.

The constellation which contains the Andromeda Galaxy, or M31. The Andromeda galaxy is the most distant object that can be glimpsed with the naked eye. Its small, eliptical companion galaxies, M32 and M110, can be seen with a telescope. Andromeda also contains a binary star of contrasting colors called Gamma Andromedae.

A spiral galaxy in the constellation Andromeda. The Andromeda Galaxy is called M31 in the Messier catalogue. The Andromeda Galaxy was the first galaxy discovered outside the Milky Way. In 1924, when studying photographs of Cepheid variable stars in M31, Edwin Hubble discovered that these stars were much fainter than Cepheids observed within the Milky Way. The faintness of the images indicated that M31 is much further away than the diameter of the Milky Way; therefore it must exist outside the Milky Way. The Andromeda Galaxy is currently estimated to be 2.4 million light-years away. Measurements of its apparent size and brightness imply that it is larger than the Milky Way.

The amount of rotational motion contained in a body or in a system of masses. The principle of conservation of angular momentum implies that if a collapsing cloud is rotating, it will spin faster and faster as it shrinks. Most stars, particular lower-mass, cooler stars like the Sun, have lost most of their angular momentum and spin rather slowly. Magnetic fields connect the body of such a star to material spun off the surface, enabling the material to carry off the star’s angular momentum. More massive stars usually continue to spin rapidly because they do not have this magnetic assistance.

Before sending human beings into space, both Russia and the United States launched animals to study how spaceflight affects living things. In the 1940s, the US Army launched two monkeys on a ballistic trajectory in the nose cones of captured German V-2 rockets. The monkeys did not survive. On September 20, 1951, 11 mice and a monkey reached the edge of space and returned to Earth safely on an Aerobee rocket. Laika, a dog, was the first living creature to orbit the Earth. She was launched by Russia in November 1957, and was kept in a pressurized compartment. She appeared comfortable. Russia sent more dogs into space between 1957 and 1966. In December 1959, animals began to be used to test NASA’s Mercury capsule when Sam, a rhesus monkey, flew a suborbital flight. Miss Sam, another Rhesus monkey, flew in January 1960. Ham, a chimpanzee, made a suborbital flight in January 1961, and another chimpanzee, named Enos, flew a two-orbit flight in November 1961.

The opposite of creation. Creation is the process by which the Universe’s matter was brought into existence; annihilation is the process by which matter disappears from the Universe.

Both creation and annihilation are subject to the same laws of conservation of matter and energy. Annihilation creates a large flux of gamma rays. When a proton annihilates with an antiproton, the matter is converted into pions, which rapidly decay into gamma rays and neutrinos. When an electron annihilates with an anti-electron, or positron,the matter is converted into gamma rays.

A red supergiant star, at the heart of the constellation Scorpius. Antares’ diameter is about 400 times that of the Sun. Antares varies in brightness by a few tenths of a magnitude. A much smaller and hotter companion orbits Antares approximately every 900 years.

The idea that the fundamental constants of the Universe exists because they are the only ones consistent with the evolution of intelligent life in the Universe. The anthropic principle attempts to answer such questions as why space has three dimensions: because planetary orbits would not be stable otherwise. The anthropic principle provides an explanation for some coincidences found in Nature, such as the resonance that occurs in the nuclear reactions in which carbon is synthesized in the stars.

The anthropic principle gives human beings a special role in the Universe, and some physicists believe this is counter to the objectivity of physics.