Patrick Moore’s Practical Astronomy Series Forothertitlespublishedintheseries,goto www.springer.com/series/3192 . The Moon in Close-up A Next Generation Astronomer’s Guide John Wilkinson JohnWilkinson ISSN1431-9756 ISBN978-3-642-14804-0 e-ISBN978-3-642-14805-7 DOI10.1007/978-3-642-14805-7 SpringerHeidelbergDordrechtLondonNewYork #Springer-VerlagBerlinHeidelberg2010 Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerialis concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting, reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublication orpartsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9,1965, initscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violationsareliable toprosecutionundertheGermanCopyrightLaw. Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnotimply, evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotective lawsandregulationsandthereforefreeforgeneraluse. Coverillustration:NASA Coverdesign:eStudioCalamarSteinen Coverfigure:ThecraterDaedalusontheMoon’sfarsideasseenbytheLunarOrbiterspacecraft(NASA). SeealsoFig.1.23inthebook. Printedonacid-freepaper SpringerispartofSpringerScienceþBusinessMedia(www.springer.com) Preface Throughout history, our Moon has been a constant source of fascina- tion. Ancient civilizations worshipped it and used it to measure time and predict the rise and fall of the oceans. The Moon is also the most dominant member of the night sky being much brighter than all the planetsandthebackgroundofstars.TheMoonissolargeandsocloseto Earththatsomeofitssurfacefeaturesarereadilyvisibletothenakedeye. Withoutatelescope,youcaneasilyseedarkgreyandlightgreyareasthat cover vast areas of the Moon. The invention of the telescope in 1608 enabled observers such as Galileo to observe for the first time the various features on the Moon’s surface.Galileowasabletoobservethecraters,mountainsand“seas”on theMoon.Astelescopesimproved,sodidthequalityofobservationsand ourunderstandingoftheMoon’sroleintheSolarSystem.Then,50years ago, space travel changed everything. ThefirstspacecrafttoreachtheMoonwastheUSSR’sLuna1in1959. Sincethenmorethan70spacecrafthavevisitedtheMoon.Someofthese spacecrafthavebeenroboticwhileothershavebeenmanned.Amongthe roboticspacecraftwastheJupiterboundprobenamedGalileo.Scientists tested Galileo’s instruments with Moon observations before it made its historic journey to explore the Jupiter system. Perhaps the most outstanding technological achievement in space traveloccurredinJuly1969whenUSAastronautNeilArmstrongbecame the first human to walk on the Moon’s surface. Since then, a total of 12 astronauts have walked on the Moon’s surface and returned to Earth with samples of lunar rocks. These rocks greatly improved our under- standing of lunar geology. v vi Preface Currently robotic spacecraft from around the world are working together to launch a new era of lunar science. Plans are underway to send astronauts back to the Moon as part of a larger strategy to explore other planets in our solar system. A number of countries have begun exploring the Moonvia unmanned spaceprobes. The USA has been the most active with the probes Clementine (1994), Lunar Prospector (1999), and Smart 1 (2003). More recently, the USA’s unmanned Lunar ReconnaissanceOrbiter(2009)issearchingfordepositsofwatericethat prospectiveMooncolonistscouldusetomakeair,fuelandperhapseven grow food. Other space probes are charting the Moon for valuable mineral deposits. Three other countries have also active lunar explora- tion programs – Japan (Kaguya probe, 2007), China (Chang’e program, 2007) and India (Chandrayaan program, 2008). Information collected by these recent space probes has changed our knowledgeandunderstandingoftheMoon,particularlyitsgeology.This book presents those findings in a way that is useful for amateur astron- omers,students,educatorsandanyoneinterestedintheMoon.Thebook combinesnewlyacquiredscientificunderstandingwithdetaileddescrip- tionsandphotographsofthemanylunarfeatures.Amateurastronomers using telescopes and binoculars can observe these features from Earth. This book is special in that the final chapter is divided into 17 Study Areaswith eachareacontaining photographic mapsofthelunarsurface forreaderstousetoexploretheMoonwithbinocularsoranastronomi- cal telescope. Readers using the photographic maps will gain a better understanding about the Moon’s topography and geology. John Wilkinson Acknowledgements The author and publisher are grateful to the following for the use of photographsinthispublication:NationalAeronauticsandSpaceAdmin- istration (NASA), Lunar and Planetary Institute (LPI/USA). All photo- graphsusedasmapshavebeensourcedfromtheConsolidatedLunarAtlas producedbytheLPIwithpermission.Allotherphotographsaresupplied bytheauthor(JW).Creditforeachphotographisgivenattheendofeach caption. While every care has been taken to trace and acknowledge copyright, the author apologises in advance for any accidental infringe- mentwherecopyrighthasprovenuntraceable.Hewillbepleasedtocome to a suitable arrangement with the rightful owner in each case. vii . Contents Preface .................................................................. v Acknowledgements ................................................... vii Chapter 1 Introducing the Moon .................................. 1 What’s New?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Early Ideas About the Moon . . . . . . . . . . . . . . . . . . . . . .5 Landmarks in Lunar Astronomy . . . . . . . . . . . . . . . . . . .7 Orbit and Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Libration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Phases of the Moon . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Sidereal and Synodic Month . . . . . . . . . . . . . . . . . . . . .17 Features of the Moon. . . . . . . . . . . . . . . . . . . . . . . . . . .18 Terms Used When Observing the Moon . . . . . . . . . . . .26 Maps of the Moon. . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 Gravity and Tidal Forces . . . . . . . . . . . . . . . . . . . . . . . .29 Atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 Magnetic Field. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Far Side of the Moon. . . . . . . . . . . . . . . . . . . . . . . . . . .35 Web Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 Chapter 2 Probing the Moon ..................................... 39 What’s New?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 ix