The Earth as a Distant Planet - A Rosetta Stone for the Search of Earth-Like Worlds

Preface

Acronyms

Contents

1 Observing the Earth

1.1 The Exploration of Our Planet

1.2 First Observations of Our Planet from the Air

1.2.1 Early Balloon Pictures

1.2.2 The Space Research

1.2.2.1 The First Attempts

1.2.2.2 The Manned Flights

1.2.2.3 The Earth Observatory

1.2.2.4 Infrared Images

1.3 The Earth–Moon System

1.4 The Solar System

1.4.1 General Characteristics

1.4.2 A View from the Edge

1.4.3 Our Environment

1.4.3.1 Nearby Stars

1.4.3.2 The Gaseous and Dusty Neighbourhood

1.4.3.3 The Galaxy

References

2 The Earth in Time

2.1 The Earth at the Present Time

2.1.1 The Interior

2.1.1.1 Inner Core

2.1.1.2 Outer Core

2.1.1.3 Mantle

2.1.1.4 Lithosphere

2.1.1.5 Energy Budget

2.1.2 Plate Tectonics

2.1.3 The Atmosphere

2.1.4 Energy Balance of the Atmosphere

2.1.4.1 Albedo

2.1.4.2 The Planet's Mean Temperature

2.1.4.3 Greenhouse Gases

2.1.4.4 2D Models

2.2 The Precambrian Era (4,500–4,550 Ma BP)

2.2.1 The Formation of the Earth: The Hadean Era

2.2.1.1 The Moon and the Earth Rotation

2.2.1.2 Late Heavy Bombardment

2.2.1.3 The Early Crust and Mantle

2.2.1.4 The Young and Faint Sun

2.2.2 The Archaean and Proterozoic Times

2.2.2.1 The Origin and Development of Life

2.2.2.2 The Carbon Dioxide Cycle

2.2.2.3 Sea-Floor Spreading and Continental Growth

2.2.2.4 Greenhouse Gases and Paleoclimate

2.2.2.5 Oxygen, Ozone and Ultraviolet Radiation

2.2.2.6 The Snowball Earth

2.3 The Phanerozoic Era

2.3.1 The Drift, Breakup and Assembly of the Continents

2.3.2 Supereruptions and Hot Spots

2.3.3 The Connection Temperature-Greenhouse Gases

2.3.4 Temporal Variations of the Magnetic Field

2.3.5 Mass Extinctions in the Fossil Record

2.3.5.1 Historical Introduction

2.3.5.2 Biological Extinctions During the Phanerozoic Era

2.3.5.3 The K/T Extinction

2.4 The Quaternary

2.4.1 The Ice Ages

2.4.2 The Present Warming: The Anthropocene

2.5 The Future of Earth

2.5.1 The End of Life

2.5.2 The End of the Earth

References

3 The Pale Blue Dot

3.1 Globally Integrated Observations of the Earth

3.1.1 Earth Orbiting Satellites

3.1.2 Observations from Long-range Spacecrafts

3.1.3 An Indirect View of the Earth: Earthshine

3.2 The Earth's Photometric Variability in Reflected Light

3.2.1 Observational Data

3.2.2 Reflectance Models

3.2.3 The Earth's Light Curves

3.2.4 The Rotational Period

3.2.5 Cloudiness and Apparent Rotation

3.2.6 Glint Scattering

3.3 Earth's Infrared Photometry

3.4 Spectroscopy of Planet Earth

3.4.1 The Visible Spectrum

3.4.2 The Infrared Spectrum

3.4.3 The Earth's Transmission Spectrum

3.5 Polarimetry of Planet Earth

3.5.1 Linear Polarization

3.5.2 Circular Polarization

References

4 The Outer Layers of the Earth

4.1 Temperature Profile and the Energy Balance

4.2 Stratosphere: The Ozone Layer

4.2.1 Natural Processes of Ozone Formation and Destruction

4.2.1.1 Ozone Formation

4.2.1.2 Ozone Destruction

4.2.1.3 Ozone Transport

4.3 Mesosphere

4.4 The Thermosphere

4.5 The Exosphere: Geocorona

4.6 Airglow

4.6.1 Nightglow

4.6.2 Dayglow

4.6.3 Twilight Airglow

4.7 The Ionosphere

4.7.1 General Structure

4.7.2 Ionosphere Indicators

4.7.3 Lightnings

4.8 The Magnetosphere

4.8.1 Description

4.8.2 Radiation Belts

4.8.3 Aurorae

4.9 Radio Emission of the Earth and Other Planets

4.10 The Earth in X-Rays

4.11 The Earth's Gamma Ray Emission

4.12 The Outer Layers of the Early Earth

References

5 Biosignatures and the Search for Life on Earth

5.1 The Physical Concept of Life

5.2 Astrobiology: New Perspectives for an Old Question

5.3 Requirements for Life

5.3.1 Biogenic Elements

5.3.2 A Solvent: Water

5.3.3 Energy Source

5.3.3.1 Solar Radiation: Photosynthesis

5.3.3.2 Chemical Energy

5.4 Biosignatures on Present Earth

5.4.1 Spectral Biosignatures in the Atmosphere

5.4.1.1 Atmospheric Carbon dioxide, Water Vapour and Ozone: The Triple Fingerprint

5.4.1.2 Other Atmospheric Biosignatures

5.4.2 Chlorophyll and Other Spectral Biosignatures of the Planetary Surface: The Red Edge

5.4.3 Chirality and Polarization as Biosignatures

5.5 Biosignatures on Early-Earth

5.6 Life in the Universe

5.6.1 Circumstellar Habitable Zone

5.6.1.1 Stellar Constraints

5.6.1.2 M Stars and Tidal Locking

5.6.1.3 Planetary Constraints

5.6.1.4 The Continuously Habitable Zone

5.6.2 Additional Constraints for Habitability

5.6.2.1 Short-term Stellar Variability

5.6.2.2 Ultraviolet and Ionizing Radiation

5.6.3 Galactic Habitable Zone

5.7 Signatures of Technological Civilizations

5.7.1 Night Lights

5.7.2 Spectral Features

5.7.3 Artificial Radioemission

5.7.4 Nuclear Explosions

5.7.5 Extraterrestrial Pulses

References

6 Detecting Extrasolar Earth-like Planets

6.1 First Attempts to Discover Exoplanets

6.2 The Mass Limit: From Brown Dwarfs to Giant Planets

6.2.1 The Brown Dwarf Desert

6.3 The Detection of Earth-like Planets: A Complex Problem

6.3.1 Brightness Ratio

6.3.2 Angular Distance

6.4 Methods for the Detection of Exoplanets

6.4.1 Indirect Detection of Exoplanets

6.4.1.1 Astrometry

6.4.1.2 Radial Velocity

6.4.1.3 Pulsar Timing

6.4.1.4 Microlensing Events

6.4.1.5 Transits

6.4.1.6 Differential Spectro-photometry During Transits

6.4.1.7 Miscellaneous Indirect Detection Methods

6.4.2 Direct Observations of Exoplanets

6.4.2.1 Coronagraphy

6.4.2.2 Nulling Interferometry

6.4.2.3 Polarimetry

6.5 The Next 20 Years

References

7 The Worlds Out There

7.1 Definition of a Planet

7.2 Our Solar System

7.2.1 General Facts

7.2.2 Chemical Abundances in the Solar System

7.2.3 Giant Planets

7.2.4 Terrestrial Planets

7.2.5 Dwarf Planets and Other Minor Bodies

7.2.5.1 Asteroid Belt

7.2.5.2 Kuiper Belt

7.2.5.3 Oort Cloud

7.3 Planetary Atmospheres

7.4 Statistical Properties of the Extrasolar Giant Planets

7.4.1 Mass Distribution

7.4.2 Hot Jupiters

7.4.3 Eccentric Planets

7.4.4 Role of the Metallicity

7.4.5 Stellar Masses

7.5 Types of Terrestrial Planets

7.5.1 Rocky Planets

7.5.2 Super-Earths

7.5.2.1 Internal Structure

7.5.2.2 Surface Appearance and Habitability

7.5.3 Carbon–Oxygen Ratio: The Carbon Planets

7.5.4 Super-Mercuries

7.5.5 Planets Around Pulsars in Metal-Poor Environments

7.5.6 Terrestrial Planets Around Giant Planets:The Rocky Moons

7.5.7 Free-Floating Planets

7.6 Characterization of Exoplanets

7.6.1 Mass–Radius Relationships

7.6.2 Atmospheres of Exoplanets

7.6.2.1 HD 189733b

7.6.2.2 HD 209458b

7.6.2.3 Terrestrial Planets

7.6.3 Radio Emission of Exoplanets

7.7 Terraformed Planets

7.8 Expect the Unexpected

References

8 Extrasolar Planetary Systems

8.1 The Origin of the Solar System: Early Attempts

8.1.1 Nebular Theory

8.1.2 Catastrophic Theories

8.2 Formation of Planetary Systems

8.2.1 Stellar Formation

8.2.2 The Early Accretion Phase

8.2.3 The Protoplanetary and Debris Disks

8.2.4 Formation of Giant Planets

8.2.5 Formation of Terrestrial Planets

8.3 Planetary Orbits

8.3.1 Basic Orbital Elements

8.3.2 Keplerian Orbits

8.3.3 Harmony and Chaos

8.3.3.1 Historical Background

8.3.4 Relevant Parameters of Dynamical Stability

8.3.4.1 Uncertainty

8.3.5 Resonances in Planetary Systems

8.3.5.1 Laplace Resonances

8.3.5.2 Kirkwood Gaps

8.3.5.3 Spin–Orbit Resonance

8.3.6 Lagrangian Points

8.4 The Dynamically Habitable Zone

8.5 Architecture of Planetary Systems

8.5.1 Systems with Hot Jupiters: The Planetary Migration

8.5.1.1 Planetesimal-driven Migration

8.5.1.2 Planet–Planet Scattering

8.5.1.3 The LHB Event and the Nice Model

8.5.1.4 Interaction with a Distant Companion Star

8.5.1.5 Gas Disk Migration

8.5.1.6 Stopping the Migration

8.5.1.7 Survival of Terrestrial Planets

8.5.2 Binary Systems

8.5.3 Multiple Planetary Systems

8.5.3.1 Gliese 581

8.5.3.2 Gliese 876

8.5.3.3 Upsilon Andromeda (HD 9826)

8.5.3.4 55 Cancri (HD 75732)

8.5.3.5 47 UMa (HD 95128)

8.5.3.6 HD 69830

8.5.3.7 HD160691 ( Arae)

8.5.3.8 HD 40307

8.6 Violence and Harmony

References

9 Is Our Environment Special?

9.1 Is the Sun Anomalous?

9.1.1 Singularity

9.1.2 Mass

9.1.3 Location

9.1.4 Age

9.1.5 Chemical Composition: Metallicity

9.1.6 Magnetic Activity

9.1.7 Solar Analogs

9.2 Is the Solar System Unique?

9.2.1 Nature vs. Nurture

9.2.1.1 Formation

9.2.1.2 Stellar Encounters

9.2.1.3 Gravitational Interactions: LHB Events

9.2.1.4 Mercury: The Achilles Heel

9.2.2 Debris Disks

9.2.3 The Energetic Environment

9.2.4 Solar System Analogs

9.3 Is the Earth Something Special?

9.3.1 Habitability

9.3.2 Variations of Orbital Parameters

9.3.3 Presence of a Large Satellite

9.4 The Ultimate Factor: Life

References

Index