A-OK Quick reference
A Dictionary of Space Exploration (3 ed.)
‘Very OK’ or ‘Great’. John ‘Shorty’ Powers, NASA's public-relations officer, introduced the term by misquoting astronaut Alan *Shepard during the first sub-orbital flight in ...
A-type asteroid Quick reference
A Dictionary of Astronomy (3 ed.)
A rare type of asteroid that has both a moderately high albedo (0.13–0.35) and an extremely reddish spectrum at wavelengths shorter than 0.7 ...
A-type rocket Quick reference
A Dictionary of Space Exploration (3 ed.)
A name used in the West for a series of Soviet rocket boosters. The A-1 launched *Sputnik and the cosmonaut ...
AAO Quick reference
A Dictionary of Astronomy (3 ed.)
Abbr. for *Australian Astronomical Observatory.
AAVSO Quick reference
A Dictionary of Astronomy (3 ed.)
Abbr. for *American Association of Variable Star Observers.
A band Quick reference
A Dictionary of Astronomy (3 ed.)
Abell Catalogue Quick reference
A Dictionary of Astronomy (3 ed.)
A catalogue of 2712 rich clusters of galaxies published in 1958 by the American astronomer George Ogden Abell (1927–83...
Abell cluster Quick reference
A Dictionary of Astronomy (3 ed.)
Abell clusters Reference library
The Oxford Companion to Cosmology
George Abell is best remembered for his catalogue of clusters of galaxies, a result of his PhD work at the California Institute of Technology (Caltech), published in ...
Abell radius Quick reference
A Dictionary of Astronomy (3 ed.)
A radius of about 2 megaparsecs within which at least 50 galaxies of a particular range of brightness must be found if the cluster is to qualify as an ...
aberration, optical Quick reference
A Dictionary of Astronomy (3 ed.)
An imperfection or error in the image produced by a lens, mirror, or optical system. There are six types of aberration: ...