Document file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Astron 192115960/nlReader.dll@BookID=18322&FileName=Cover.html [9/29/2007 7:46:58 PM] Document Page i A Dictionary of Astronomy file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Astron %200192115960/nlReader.dll@BookID=18322&FileName=I.html [9/29/2007 7:46:59 PM] Document Page ii The most authoritative and up-to-date reference books for both students and the general reader. Abbreviations ABC of Music Accounting Archaeology* Architecture* Art and Artists Art Terms* Astronomy Bible Biology British Women Writers Buddhism* Business Card Games Chemistry Christian Church Classical Literature Classical Mythology* Colour Medical Dictionary Colour Science Dictionary Computing Dance* file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Ast 192115960/nlReader.dll@BookID=18322&FileName=II.html (1 of 4) [9/29/2007 7:46:59 PM] Document Dates Earth Sciences Ecology Economics Engineering* English Etymology English Folklore* English Grammar English Language English Literature English Place-Names Euphemisms Film* Finance and Banking First Names Food and Nutrition Fowler's Modern English Usage Geography Handbook of the World* Humorous Quotations Irish Literature* Jewish Religion King's and Queens* King's English file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Ast 192115960/nlReader.dll@BookID=18322&FileName=II.html (2 of 4) [9/29/2007 7:46:59 PM] Document Law Linguistics Literary Terms Mathematics Medical Dictionary Medicines* Modern Design* Modern Quotations Modern Slang Music Nursing Opera Paperback Encyclopedia Philosophy Physics Plant-Lore Plant Sciences Political Biography Political Quotations Politics Popes Proverbs Psychology* Quotations file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Ast 192115960/nlReader.dll@BookID=18322&FileName=II.html (3 of 4) [9/29/2007 7:46:59 PM] Document Sailing Terms Saints Science Shakespeare Ships and the Sea Sociology Statistics* Superstitions Theatre Twentieth-Century Art Twentieth-Century Poetry Twentieth-Century World History Weather Facts Who's Who in Opera* Who's Who in the Twentieth Century Word Games World Mythology World Religions* Writers' Dictionary Zoology *forthcoming file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Ast 192115960/nlReader.dll@BookID=18322&FileName=II.html (4 of 4) [9/29/2007 7:46:59 PM] Document Page iii A Dictionary of Astronomy Edited by Ian Ridpath Oxford New York OXFORD UNIVERSITY PRESS file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Astron 00192115960/nlReader.dll@BookID=18322&FileName=III.html [9/29/2007 7:47:00 PM] Document Page iv OXFORD UNIVERSITY PRESS Great Clarendon Street, Oxford OX2 6DP Oxford University Press is a department of the University of Oxford.It furthers the University's objective of excellence in research, scholarship,and education by publishing worldwide in Oxford New York Athens Auckland Bangkok Bogotá Buenos Aires CalcuttaCape Town Chennai Dares Salaam Delhi Florence Hong Kong Istanbul Karachi Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi Paris São Paulo Singapore Taipei Tokyo Toronto Warsaw with associated companies in Berlin Ibadan Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries© Oxford University Press 1997 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose this same condition on any acquirer British Library Cataloguing in Publication Data Data available Library of Congress Cataloging in Publication Data A dictionary of astronomy / edited by Ian Ridpath. 1. AstronomyDictionaries. I. Ridpath, Ian. QB14.D52 1997 520'.3dc21 97-14619 ISBN 0-19-211596-0 (pbk.) 3 5 7 9 10 8 6 4 2 Typeset by Jayvee, Trivandrum, India Printed in Great Britain by Mackays of Chatham plc Chatham, Kent file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Astron 200192115960/nlReader.dll@BookID=18322&FileName=IV.html [9/29/2007 7:47:00 PM] Document Page v Contents List of Contributors vi Preface vii A Dictionary of Astronomy 1 Appendix 525 file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Astro 200192115960/nlReader.dll@BookID=18322&FileName=V.html [9/29/2007 7:47:00 PM] Document Page vi List of Contributors Editor Ian Ridpath FRAS Contributors M. A. Barstow BA, PhD, CPhys, MInstP, FRAS Neil Bone BSc P. A. Charles BSc, PhD C. J. Clarke BA, DPhil R. J. Cohen MSc, BSc, PhD Peter Coles MA DPhil, FRAS Storm Dunlop FRAS M. G. Edmunds MA, PhD, FRAS R. M. Green MA, PhD D. H. P. Jones MA, BSc, PhD, FRAS A. W. Jones PhD, CPhys, MInstP C. Kitchin BA, BSc, PhD, FRAS John W. Mason BSc, PhD, FRAS Andrew Murray MA J. B. Murray MA, MPhil, PhD Gillian Pearce BSc, PhD, BM, BCh, FRAS Kenneth J. H. Phillips BSc, PhD file:///E|/Unposted/Netlib/A%20Dictionary%20of%20Ast 192115960/nlReader.dll@BookID=18322&FileName=VI.html (1 of 2) [9/29/2007 7:47:01 PM] [...]... *angstrom AAO Abbr for *Anglo-Australian Observatory AAS Abbr for *American Astronomical Society AAT Abbr for *Anglo-Australian Telescope AAVSO Abbr for *American Association of Variable Star Observers A band A broad *Fraunhofer line in the Sun's spectrum at around 760 nm, due to absorption by oxygen in the Earth's atmosphere Because the oxygen is in molecular form, the A band is actually a group of. .. provided by Alfvén waves propagating from the outer layers of the Sun The waves are named after H O G *Alfvén See also MAGNETOHYDRODYNAMICS Algenib The star Gamma Pegasi, a B2 subgiant of magnitude 2.8, lying 490 l.y away Algenib is also an alternative name for the star *Mirfak (Alpha Persei) Algieba The star Gamma Leonis It is a binary consisting of a K1 giant of magnitude 2.6 and a G7 giant of magnitude... image is transferred without bringing it to a focus Afocal photography, for example, involves pointing a camera, focused on infinity, into the eyepiece of a telescope whose image also appears at infinity When an image is transferred as a beam of parallel light rays, the beam is termed an afocal beam AGB star Abbr for *asymptotic giant branch star Agena Alternative name for the star *Hadar or Beta Centauri... horizon around the edge They are used in particular for meteor and fireball 'patrols' A simple design of all-sky camera consists of a convex mirror which reflects the image of the sky to a camera above it, pointing downward More advanced designs use ultra-wide-angle lenses Almach The star Gamma Andromedae; also spelled Almaak or Alamak It is a double star consisting of a K3 bright giant and a B9 dwarf, magnitudes... publication, usually issued yearly, listing predicted dates and times of forthcoming celestial phenomena and positions of celestial objects, along with other information of interest to astronomers, navigators, and surveyors Examples are The *Astronomical Almanac and The *Nautical Almanac almucantar A small circle on the celestial sphere that is parallel to the horizon All objects on an almucantar are at... such as *astrolabes Alioth The star Epsilon Ursae Majoris It is an A0 subgiant of magnitude 1.8 with strong lines of chromium in its spectrum It is a variable of the Alpha2 Canum Venaticorum type, fluctuating by a few tenths of a magnitude with a period of 5.1 days It lies 65 l.y away Alkaid The star Eta Ursae Majoris, also known as Benetnasch It is a B3 dwarf of magnitude 1.9, lying 140 l.y away Allegheny... to mean the transfer of heat vertically within a planetary body, for example by hot, molten material rising through the lithosphere of a planet aeon A period of 109 years (i.e a billion years); US eon aerial Another name for an *antenna aerobraking The technique of using the atmospheric drag of a planet to modify the orbit of a spacecraft, thereby saving propellant It was first used at another planet... Herculis star, the material may form an accretion column over each magnetic pole, rather than a disk The gravitational energy that is released can cause high ultraviolet or X-ray luminosities, and may accelerate jets of material from the disk to very high speeds Achernar The star Alpha Eridani, a B3 dwarf of magnitude 0.46, ninth-brightest in the sky, about 70 l y away Its name comes from Arabic and means... increasing richness from 1 to 5, and increasing distance from 1 to 6 The approximate frequency of Abell clusters is one per 2.4×105 cubic megaparsecs Abell radius 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 *Abell cluster aberration, constant of See ANNUAL ABERRATION aberration, optical An imperfection... Abbr for *Astronomical Journal al- For personal names beginning 'al-', see under the next element of the name Albategnius Latinized name of al-*Battani al-Battani See under BATTANI albedo The fraction of the total light or other radiation falling on a non-luminous body, such as a planet, or on a planetary surface feature, that is reflected from it In general, the albedo is equal to the amount of light . Cataloguing in Publication Data Data available Library of Congress Cataloging in Publication Data A dictionary of astronomy / edited by Ian Ridpath. 1. Astronomy Dictionaries. I. Ridpath, Ian PM] Document Page 1 A Å Symbol for *angstrom. AAO Abbr. for *Anglo-Australian Observatory. AAS Abbr. for *American Astronomical Society. AAT Abbr. for *Anglo-Australian Telescope. AAVSO Abbr. for *American. category. abundance See ELEMENTS, ABUNDANCE OF. Acamar The star Theta Eridani. It is a double star, consisting of an A4 subgiant and an A1 dwarf, magnitudes 3.4 and 4.4, about 90 l.y. away. file:///E|/Unposted/Netlib /A% 2 0Dictionary% 2 0of% 20Ast