A Dictionary of Astronomy (Oxford Paperback Reference) (Oxford Quick Reference)
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The revised second edition of this established dictionary contains over 4,300 up-to-date entries on all aspects of astronomy. Compiled with the help of thirty-four expert contributors under the editorship of renowned author Ian Ridpath, the book covers everything from space exploration and the equipment involved, to astrophysics, cosmology, and the concept of time--plus biographical entries on eminent astronomers and worldwide coverage of observatories and telescopes. The appendices include tables of Apollo lunar landing missions, the constellations, and a table of planetary data. The entries have been fully revised and updated and fifty new entries have been added. The content is enhanced by web links which are regularly updated on a companion website.
The zodiac, popularly known as the water-carrier, through which the Sun passes from the third week of February to the second week of March. Its brightest stars are Alpha Aquarii (Sadalmelik) and Beta Aquarii (Sadalsuud), both of magnitude 2.9. It contains the 7th-magnitude globular cluster M2, the *Helix Nebula, and the *Saturn Nebula. Three meteor showers radiate from Aquarius each year, the *Delta Aquarids, the *Eta Aquarids, and the *Iota Aquarids. aqueous alteration A process in which changes.
Ancient times to demonstrate and observe the movements of the heavens. It consists of a number of rings (armillaries) representing celestial great circles such as the meridian, horizon, celestial equator, and ecliptic, arranged to form a skeletal celestial sphere. Armillary spheres can still be found in the form of equatorial sundials, in which the ring representing the celestial equator is marked with hours. The name comes from the Latin word armilla, meaning 'ring' or 'bracelet'. arm population.
In the early phases of the hot Big Bang. Although the axion is predicted to have a very tiny mass (about 10-11 of the mass of an electron) and might therefore be expected to be a form of *hot dark matter, it interacts so file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Ast...192115960/nlReader.dll@BookID=18322&FileName=41.html (2 of 2) [9/29/2007 7:47:32 PM] Document Page 42 weakly with radiation that it is, in fact, a plausible candidate for *cold dark matter. axis, optical See OPTICAL.
Blinking Planetary The planetary nebula NGC 6826 in Cygnus. It is an 8th- magnitude nebula with a 10th-magnitude central star. Alternately looking at the central star and then away causes the star and nebula to appear to blink on and off. It is about 3200 l.y. away. BL Lacertae object (BL Lac object) An apparently star-like object with a nearfeatureless spectrum; also known as a Lacertid. BL Lac objects show considerable brightness variationsoften by several magnitudes over days or weekswith high.
Per unit volume. In astrophysics, this equation is of importance in understanding the interiors and surface layers of stars, and the atmosphere of planets. The constant is named after the Austrian physicist Ludwig Edward Boltzmann (1844–1906). file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Ast...192115960/nlReader.dll@BookID=18322&FileName=60.html (1 of 2) [9/29/2007 7:47:49 PM] Document Bond, George Phillips (1825–65) American astronomer, son of W. C. *Bond. He worked closely with his.