Fascination Astronomy. A cutting-edge introduction for all those interested in the natural sciences

276 Pages·2023·14.702 MB·English

by  Arnold Hanslmeier

Arnold Hanslmeier
Fascination
Astronomy
A cutting-edge introduction for all those
interested in the natural sciences
Fascination Astronomy
Arnold Hanslmeier
Fascination Astronomy
A cutting-edge introduction for all those
interested in the natural sciences
ArnoldHanslmeier
UniversitätGraz
Graz,Austria
ISBN978-3-662-66019-5 ISBN978-3-662-66020-1 (eBook)
https://doi.org/10.1007/978-3-662-66020-1
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Preface
Astronomy is a science that pushes the boundaries. One has to deal with unimaginably
hugedimensionsofspaceandtime,unimaginablehotandalsocoldobjects,andeveninour
solar system, which is now also well explored by satellite missions, there are constantly
new discoveries. In addition, astronomers cannot work directly with their objects of
research. The only information we get about stars and galaxies is their radiation and
position in the sky. Nevertheless, the laws of physics allow us to get information about
these objects: Of many stars and galaxies we know what they are made of, how old they
are,howfartheyarefromus,etc.Findingsfromastronomyhavehadasignificantimpact
onourthinking.Theearthisbynomeansthecenter,butonlyatinyplanetintheuniverse,
whichisinfinite,yetfinite,andwhichitself hasnocenter.Inthisbook,whichoriginated
fromalecturegivenattheUniversityofGrazforstudentsofallfaculties,wewillconvey
astronomicalknowledgewithoutgoingintotoomuchphysicsandmathematics.Somewhat
deeper formulas and passages are separated from the rest of the text and can be skipped
withoutlosingthecontext.Nevertheless,theimpressionshouldbegiventhatastronomical
numbersareprovableandtheresultofcarefulmeasurements.
In the first chapter we describe the fascination of the origin of the universe. Modern
insights oftheoretical physics help here and astrophysics and physics together bring new
insightsandraisenewquestionsatthesametime.Wecoverdarkmatter,thesolarsystem,
thesun,andtheevolutionofstars.Hugesupermassiveblackholesarelocatedinthecenters
ofgalaxies,andforthefirsttimeitispossibletodetectthembyobservation.Formorethan
25yearswealsoknowplanetsoutsideoursolarsystem.Thus,attheendofthebookwetry
to give an answer to the probably most exciting question of the natural sciences: Are we
aloneintheuniverse?
Thebookisintendednotonlyforstudentsbutalsoforinterestedlaymen,aswellasfor
anyone who is interested in modern findings in natural science. Physics, especially
astrophysics,canbeextremelyexciting,Ihopemyreadersgainthisimpressionbyreading
thisbook!
This third edition of this book takes into account the latest findings from satellite
missions,suchasthefirstsuccessfulsoftlandingonacometorspectacularimagesofthe
v
vi Preface
dwarf planet Pluto, and recent missions to the Moon and Mars. Particularly exciting was
the first direct observation of gravitational waves, which Einstein predicted but did not
himself believe would ever be detected. Recent findings in exoplanet research and
examples of exoplanet systems are discussed. Errors have been corrected and numerous
newillustrationsintroducedtoaidunderstanding.
Graz,Austria ArnoldHanslmeier
Acknowledgments
IwouldliketothankMs.BettinaSaglioandMs.MeikeBarthfromSpektrumVerlagfor
their excellent cooperation. I thank my partner Anita for numerous discussions and her
understandingandpatience.
Graz,December2022.
vii
Contents
1 TheForcesthatShapetheUniverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Gravity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 NewtonandtheApple. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.2 WhereDoesGravityStop?. . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.3 HowtheSolarSystemHoldsTogether. . . . . . . . . . . . . . . . . . 3
1.1.4 FromthePlanetarySystemtotheUniverse. . . . . . . . . . . . .. . 4
1.2 TheElectromagneticForce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.1 Charges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.2 TheCoulombForce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2.3 Atoms:MiniaturePlanetarySystems. . . . . . . . . . . . . . . . . . . 8
1.2.4 Electricity+Magnetism=Electromagnetism. . . . . . . . . . . . . 8
1.2.5 Plasma:TheMostCommonStateofMatterintheUniverse. . 11
1.3 TheStrongandtheWeakForce. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3.1 WhatHoldsAtomicNucleiTogether?. . . . . . . . . . . . . . . . . . 11
1.3.2 TheWeakForce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4 ElementaryParticles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4.1 Interactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4.2 ElementaryParticles:Description. . .. . . . . . . . .. . . . . . . .. . 15
1.4.3 QuarksandHadrons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.4.4 WeBuildaUniverse. . . . . . .. . . . . . .. . . . . . . .. . . . . . . .. 17
2 TheBigBang:HowItAllBegan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1 TheGalaxyEscape. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1.1 MeasuringtheUniverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1.2 Hubble. . . . .. . . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. 21
2.1.3 ALookintothePast. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.1.4 GalaxyEscape. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2 TheExpansionoftheUniverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.1 AreWetheCentre?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.2 TheUniverseExpands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2.3 TheAgeoftheUniverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
ix
x Contents
2.3 TheHotBigBang. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.3.1 TheUniverseandtheRefrigerator. . . . . . . . . . . . . . . . . . . . . 29
2.3.2 BackgroundRadiation. . .. . . .. . . .. . . . .. . . .. . . .. . . . .. 29
2.3.3 BackgroundRadiationandRedshift. . . . . . . . . . . . . . . . . . . . 30
2.3.4 TemperatureFluctuationsintheEarlyUniverse. . . . . . . . . . . 32
2.3.5 DarkMatter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.4 TheOriginoftheElements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.4.1 NuclearFusionattheBeginning. . . . . . . . . . . . . . . . . . . . . . 35
2.4.2 ElementsHeavierthanHelium. . . . . . . . . . . . . . . . . . . . . . . 36
2.5 TheEarlyUniverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.5.1 TheSuperforce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.5.2 TheInflationaryUniverse. . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.6 TimeScale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.7 TheFutureoftheUniverse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.7.1 MassandEnergy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.7.2 TheNon-emptyVacuum. . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.7.3 MatterandSpace. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.7.4 EnergyandMass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.7.5 BigBangandPlanckEra. . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.8 TheUniverseandParticles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.8.1 BosonEra. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.8.2 QuarkEra. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.8.3 HadronEra. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.8.4 LeptonEra. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.8.5 TheUniverseBecomesTransparent. . . . . . . . . . . . . . . . . . . . 49
3 TheWorldofPlanets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1 GeneralPropertiesofthePlanets. . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1.1 MassandRadius. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1.2 Distances. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.1.3 Temperatures,Atmospheres. . . . .. . . . . .. . . . . . .. . . . . . .. 53
3.1.4 HowDoWeSeePlanetsintheSky?. . . . . . . . . . . . . . . . . . . 54
3.2 TheEarth-LikePlanets. . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . 58
3.2.1 Earth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.2.2 Mercury. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.2.3 Venus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3.2.4 Mars. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3.2.5 FutureMarsMissions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.2.6 Summary:WhySoDifferent?. . . . . . . . . . . . . . . . . . . . . . . . 76
3.3 TheGiantPlanets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.3.1 Jupiter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.3.2 Saturn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Contents xi
3.3.3 UranusandNeptune. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.3.4 Composition:GiantPlanets. . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.4 TheMoonsofthePlanets. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . 87
3.4.1 OurMoon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
3.4.2 TheMoonsofMars. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3.4.3 TheMoonsofJupiter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3.4.4 OtherMoonsofJupiter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.4.5 Saturn’sMoons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.4.6 TheMoonsofUranusandNeptune. . . . . . . . . . . . . . . . . . . . 101
3.4.7 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
4 DwarfPlanetsandSmallBodies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4.1 AsteroidBeltintheSolarSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4.1.1 AsteroidBelt,MainBelt. . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4.1.2 KuiperBelt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
4.1.3 TheOortCloud. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
4.2 MinorPlanets,Asteroids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
4.2.1 Observation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
4.2.2 Trojans. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
4.2.3 EarthOrbitCruisers,AreWeinDanger?. . . . . . . . . . . . . . . . 111
4.3 Comets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
4.3.1 Help,theCometIsComing. . . . . . . . . . . . . . . . . . . . . . . . . . 114
4.3.2 PeriodicComets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4.3.3 WhatAreComets?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4.3.4 CometImpacts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
4.3.5 WhereDoCometsComefrom?. . . . . . . . . . . . . . . . . . . . . . . 120
4.4 DwarfPlanets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4.4.1 Pluto. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4.4.2 OtherDwarfPlanets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
4.5 Meteoroids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.5.1 ShootingStars. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.5.2 MeteorStreams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
5 TheMechanicsoftheSky. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
5.1 TheLunarOrbit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
5.1.1 SolarandLunarEclipses. . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
5.2 EarthAxisandGyroscope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
5.2.1 Precession. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
5.2.2 Nutation. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . .. . . 133
5.3 TheAnnualCycleoftheSun. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
5.4 PlanetaryOrbits. . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . . .. 135
5.4.1 TheKeplerLaws. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
5.4.2 StabilityofthePlanetaryOrbits. . . . . . . . . . . . . . . . . . . . . . . 138