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Patrick Moore's Practical Astronomy Series P1: PAB/SPH P2: XXX SVNY352-Bone SVNY352-FM.tex February 8, 2007 8:42 Patrick Moore’s Practical Astronomy Series i P1: PAB/SPH P2: XXX SVNY352-Bone SVNY352-FM.tex February 8, 2007 8:42 Other Titles in this Series Navigating the Night Sky Observing Comets How to Identify the Stars and Constellations Nick James and Gerald North Guilherme de Almeida Telescopes and Techniques Observing and Measuring Visual Double Stars An Introduction to Practical Astronomy Bob Argyle (Ed.) Chris Kitchin Observing Meteors, Comets, Supernovae Seeing Stars and other transient Phenomena The Night Sky Through Small Telescopes Neil Bone Chris Kitchin and Robert W. Forrest Human Vision and The Night Sky Photo-guide to the Constellations How to Improve Your Observing Skills A Self-Teaching Guide to Finding Your Way Michael P. Borgia Around the Heavens How to Photograph the Moon and Planets Chris Kitchin with Your Digital Camera Solar Observing Techniques Tony Buick Chris Kitchin Practical Astrophotography How to Observe the Sun Safely Jeffrey R. Charles Lee Macdonald Pattern Asterisms The Sun in Eclipse A New Way to Chart the Stars Sir Patrick Moore and Michael Maunder John Chiravalle Transit Deep Sky Observing When Planets Cross the Sun The Astronomical Tourist Sir Patrick Moore and Michael Maunder Steve R. Coe Light Pollution Visual Astronomy in the Suburbs Responses and Remedies A Guide to Spectacular Viewing Bob Mizon Antony Cooke Astronomical Equipment for Amateurs Visual Astronomy Under Dark Skies Martin Mobberley A New Approach to Observing Deep Space The New Amateur Astronomer Antony Cooke Martin Mobberley Real Astronomy with Small Telescopes Lunar and Planetary Webcam User’s Guide Step-by-Step Activities for Discovery Martin Mobberley Michael K. Gainer Choosing and Using a Schmidt-Cassegrain The Practical Astronomer’s Deep-sky Telescope Companion A Guide to Commercial SCT’s and Jess K. Gilmour Maksutovs Observing Variable Stars Rod Mollise GerryA.Good The Urban Astronomer’s Guide Observer’s Guide to Stellar Evolution A Walking Tour of the Cosmos for City The Birth, Life and Death of Stars Sky Watchers Mike Inglis Rod Mollise Field Guide to the Deep Sky Objects Astronomy with a Home Computer Mike Inglis Neale Monks Astronomy of the Milky Way More Small Astronomical Observatories The Observer’s Guide to the Southern/Northern Sir Patrick Moore (Ed.) Sky Parts 1 and 2 hardcover set The Observer’s Year Mike Inglis 366 Nights in the Universe Astronomy of the Milky Way Sir Patrick Moore (Ed.) Part 1: Observer’s Guide to the Northern Sky Care of Astronomical Telescopes and Mike Inglis Accessories Astronomy of the Milky Way A Manual for the Astronomical Observer Part 2: Observer’s Guide to the Southern Sky and Amateur Telescope Maker Mike Inglis M. Barlow Pepin (continued after index) ii P1: PAB/SPH P2: XXX SVNY352-Bone SVNY352-FM.tex February 8, 2007 8:42 Aurora Observing and Recording Nature’s Spectacular Light Show Neil Bone iii P1: PAB/SPH P2: XXX SVNY352-Bone SVNY352-FM.tex February 8, 2007 8:42 Neil Bone ‘The Harepath’ Mile End Lane Apulduram Chichester West Sussex PO20 7DZ UK [email protected] Library of Congress Control Number: 2006940469 Patrick Moore’s Practical Astronomy Series ISSN 1617-7185 ISBN-10: 0-387-36052-2 e-ISBN-10: 0-387-68469-7 ISBN-13: 978-0-387-36052-2 e-ISBN-13: 978-0-387-68469-7 Printed on acid-free paper. C 2007 Springer Science+Business Media, LLC All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. 987654321 springer.com iv P1: PAB/SPH P2: XXX SVNY352-Bone SVNY352-FM.tex February 8, 2007 8:42 Contents Preface ........................................................ ix 1. Atmospheric Phenomena ....................................... 1 AuroraeinHistory............................................. 2 Aurorae in Mythology .......................................... 3 Other Atmospheric Phenomena .................................. 7 Haloes.................................................... 7 Sun-Pillars and Related Phenomena ............................. 10 Rainbows .................................................. 11 Meteors..................................................... 12 Space Weather ................................................ 16 2. Causes of the Aurora ........................................... 19 TheVariableSun.............................................. 20 The Sun as a Star .............................................. 24 Sunspots and the Solar Magnetic Field ........................... 27 The Active Chromosphere and Corona ........................... 29 Coronal Holes .............................................. 31 Solar Flares ................................................. 32 Linking the Sun and the Earth—The Solar Wind ................... 34 New Insights on Coronal Mass Ejections and Solar Flares ............ 36 Interactions with the Solar Wind .................................. 37 Comets.................................................... 37 Earth’sMagnetosphere........................................ 40 StructureoftheMagnetosphere.............................. 40 TheVanAllenBelts........................................ 43 Plasma Movements and Currents in the Magnetosphere; theAuroralOvals........................................ 44 Auroral Activity Types and Causes ................................ 49 Auroral Substorms ........................................... 49 GeomagneticStorms......................................... 50 Other Effects Associated with CMEs ........................... 51 CoronalHoleAurorae........................................ 52 Sector Boundary Crossings and Chromospheric Filament Disappearances ........................................... 53 Auroral Emissions ........................................... 53 Other Solar Effects on the Atmosphere ............................. 57 The Ionosphere ............................................. 57 v P1: PAB/SPH P2: XXX SVNY352-Bone SVNY352-FM.tex February 8, 2007 8:42 vi Contents The Heliosphere ............................................... 58 Effects on Terrestrial Climate ................................... 60 3. Auroral Forecasting ............................................ 63 Aurorae and the Sunspot Cycle ................................... 64 Keeping an Eye on the Possibilities for Auroral Activity—The DIYApproach!.............................................. 66 Solar Observing ............................................. 66 RecentPastActivity.......................................... 70 Early Warnings of Ongoing Auroral Activity ......................... 72 MagneticEffects............................................. 72 Magnetometers............................................. 72 BehavioroftheMagneticField................................. 74 Indices of Geomagnetic Activity .................................. 76 TheaaIndex............................................... 76 TheKpIndex............................................... 76 TheApIndex............................................... 77 RadioAurorae................................................ 77 Internet Resources ............................................. 79 4. Observing the Aurora .......................................... 81 AuroralActivityatHighLatitudes................................. 81 TheAuroralZones........................................... 82 Location,Location,Location................................... 83 Polar Cusp Aurorae ............................................ 83 Polar Cap Absorptions (PCA) .................................... 84 ThetaAurora................................................. 85 Substorm Events .............................................. 86 Geomagneticstorms........................................... 88 AuroralActivityatLowerLatitudes................................ 88 GeomagneticStorms........................................... 89 CoronalHoleAurorae.......................................... 97 “Flash Aurora” ................................................ 97 VisualObservation............................................ 98 Photography ................................................. 102 5. Historical Aurorae and More Recent Events ......................... 105 Aurorae in Classical Times ....................................... 105 AuroralRecordsfromtheDarkandMiddleAges..................... 106 TheNineteenthCentury........................................ 108 AuroraeintheTwentiethCentury................................. 108 The Great Aurora of 13–14 March 1989 .......................... 109 OtherEventsinCycle22...................................... 111 The Major Aurora of 8–9 November 1991 ........................ 113 TheStrangeCaseofCycle23................................... 114 The Aurora of 6–7 April 2000 .................................. 115 The Bastille Day Event, 15–16 July 2000 .......................... 116 March–April 2001—A Rash of Sunspots
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