Alien Skies (eBook)

Frédéric Pont teaches astrophysics at the University of Exeter (UK). He has lived and worked in Switzerland, Japan, Chile and France, and has participated in the discovery of many extra-solar planets with fellow researchers in Europe and the US. He now studies the atmosphere of some of these planets, using the Hubble Space Telescope and the largest ground-based telescopes available. He has also worked as a science writer for the Rolex Awards for Enterprise in Geneva. Born Swiss, Pont loves mountains, cheese and, somewhat less predictably, books. He now spends most of his time on planet Earth (because he quite likes its atmosphere) and currently resides in the United Kingdom.

Acknowledgments 6
Contents 8
Prologue 9
Chapter 1: The Home Planet 14
Earth’s atmosphere: a new look at an old friend 14
The role of pressure 19
The role of temperature 20
Stratosphere and ozone layer 21
Earth’s double glazing 22
Atmospheric circulation 23
Water cycle 25
Astronomer’s chemistry 26
Carbon-rock cycle 27
The atmosphere as a machine 28
The mighty ocean 28
The role of life 30
A normal atmosphere? 31
The ages of Earth 31
Chapter 2: Venus 33
Turning Earth into Venus 36
Greenhouse to madhouse 37
Water escape 38
Volcanic gases 39
The real Venus 40
The clouds of Venus 41
The role of sulphur 43
Super-rotation 45
Being there 46
Chapter 3: Mars 48
Little brother 48
Earth versus Mars 49
Marsaforming Earth: moving away from the Sun 50
Marsforming Earth: making the planet smaller 51
The real Mars 52
The role of dust 55
Martian climate 57
Martian dreams 59
Three siblings 62
Chapter 4: Titan 63
Surface features 64
The planetary explorers 65
Lakes of methane 67
Methane cycle 67
Iceball Titan 69
Cryovolcanism 69
Titan’s haze 71
Photochemical haze vs condensation clouds 71
Life in liquid methane 72
Living atmospheres 73
Being there 74
Chapter 5: Giant planets 75
Gas and ice giants 77
The formation of planets 77
Gas capture and ice line 78
Three types of planets 80
Uranium-core planets? 81
Deep inside 81
Atmosphere of Jupiter 83
Clouds 83
Circulation and weather 86
Patterns of circulation 87
Jupiter weather bulletin 89
The role of turbulence 89
Chapter 6: Hot Jupiters 91
Gas giant exoplanets 91
Hot planets 92
A hot Jupiter tour 94
Aspects of Osiris 94
Alien sunsets 97
Rock and iron clouds 97
Travel to Isis 97
Star spots 98
Aspects of Isis 99
Taking the plunge 100
How hot? 101
Interlude: Observations 104
Caution: observation-free zone ahead 109
Chapter 7: TerrestrialExoplanets 110
The planet gap 111
Armaggedons 112
Upheaval in the Solar System 113
Composition of the atmosphere of terrestrial planets 115
Exploring the zoo of imaginary terrestrial exoplanets 117
Ocean planet 117
Snowball planet 119
Steppenwolf planet 121
Different Earths 122
Rotation speed 122
Axial tilt 123
Eccentric orbit 125
Diamond planets 127
Exo plate tectonics 128
The search for life 129
Living planets 131
Chapter 8: Back to Earth 134
Birth pangs 135
Earth at 5 – ocean planet 137
Earth at 24 – oxidation and snowball 138
Earth at 35 – the boring billion 139
Earth at 40 – animal planet 140
Earth at 46 – Ice ages 141
Soiling the pool 141
Earth’s future 142
Epilogue 144
Notes on sources and complementary information 146
Index 157