This volume, together with its two companion volumes, originated in a study commis­ sioned by the United States National Academy of Sciences on behalf of the National Aeronautics and Space Administration. A committee composed of Tom Holzer, Dimitri Mihalas, Roger Ulrich and myself was asked to prepare a comprehensive review of current knowledge concerning the physics of the sun. We were fortunate in being able to persuade many distinguished scientists to gather their forces for the preparation of 21 separate chapters covering not only solar physics but also relevant areas of astrophysics and solar-terrestrial relations. It proved necessary to divide the chapters into three separate volumes that cover three different aspects of solar physics. Volumes 1 and 2 are concerned with 'The Solar Interior' and with 'The Solar Atmosphere'. This volume, devoted to 'Astrophysics and Solar-Terrestrial Relations', focuses on problems of solar physics from these two different but complementary perspectives. The emphasis throughout these volumes is on identifying and analyzing the relevant physical processes, but each chapter also contains a great deal of descriptive material. In preparing our material, the authors and editors benefited greatly from the efforts of a number of scientists who generously agreed to review individual chapters. I wish therefore to take this opportunity to thank the the following individuals for this valuable contribution to our work: S. K. Antiochos, E. H. Avrett, J. N. Bahcall, C. A. Barnes, G. Bicknell, D. Black, M. L. Blake, P. Bodenheimer, F. H. Busse, R. C. Canfield, T. R.

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16: Formation of the Sun and its Planets.- 1. Introduction.- 2. Star Formation.- 2.1. Galactic Structure.- 2.2. Stellar Properties.- 2.3. Planetary Indications.- 2.4. Interstellar Clouds.- 2.5. Observations of Forming Stars.- 2.5.1. T-Tauri Variable Stars.- 2.5.2. Nonemission, Nonvariable Pre-Main Sequence (PMS) Stars.- 2.5.3. Herbig-Haro Objects.- 2.6. Conditions for Cloud Collapse.- 2.7. Models for Star Formation.- 2.8. Modeling of Secondary Features.- 2.9. Dynamical Evolution.- 3. Cosmochemistry.- 3.1. Chronology.- 3.2. Nuclide Variations.- 3.3. Chemical Variations Among Chondritic Meteorites.- 3.4. Chemical Variations Among Differentiated Objects.- 4. Planet Formation.- 4.1. gd Gas-Dust Interaction.- 4.2. CD Disk Dynamics.- 4.3. Cpp Planetesimal Swarms.- 4.4. CPD Planet-Disk Interactions.- 4.5. CPP, CPPp Planetary Systems.- 4.6. CP(f, s)p Terrestrial Planet Formation.- 4.7. P, Pg Gaseous Protoplanet Contraction.- 4.8. WD, XD, BD Solar and External Effects on the Nebula.- 5. Implications for the Formation of the Sun and Planets.- Acknowledgement.- References.- 17: The Solar Neutrino Problem: Gadfly for Solar Evolution Theory.- 1. Introduction.- 2. Standard Theory of Solar Evolution.- 3. The Missing Solar Neutrinos 3.- 4. Have We Left Something Out?.- 4.1. Microscopic Physics 3.- 4.2. Rotation.- 4.3. Magnetic Fields.- 4.4. Accretion.- 4.5. Star Formation.- 5. The Exotic Models.- 5.1. Mixing.- 5.2. Varying G.- 5.3. Quark Catalysis.- 5.4. Depleted Maxwell Tail.- 5.5. Immiscible H-He.- 5.6. The Central Black Hole.- 5.7. Nonconventional Energy Transport.- 6. Conclusions.- Acknowledgements.- References.- 18: Stellar Chromospheres, Coronae, and Winds.- 1. Introduction.- 2. Late-Type Stars.- 2.1. Introduction.- 2.1.1. Overview.- 2.1.2. The Solar Case.- 2.1.3. Methodology.- 2.2. Observational Evidence for the Presence of Chromospheres in Late-.- Type Stellar Atmospheres.- 2.2.1. Spectral Diagnostics and Line Formation.- 2.2.2. Observational Summary and Location in the H-R Diagram.- 2.2.3. The Wilson-Bappu Effect.- 2.3. Observational Evidence for the Presence of Regions and Coronae in Late-Type Stellar Atmospheres.- 2.3.1. Transition Regions.- 2.3.2. Coronae.- 2.4. Chromospheric and Coronal Heating Mechanisms.- 2.4.1. Overview.- 2.4.2. Acoustic Wave Heating.- 2.4.3. Magnetic Heating Mechanisms.- 2.5. Observational Evidence for Mass Loss from Late-Type Stars.- 2.5.1. Main Sequence Stars.- 2.5.2. Circumstellar Absorption Lines.- 2.5.3. Chromospheric Emission Line Asymmetries.- 2.5.4. Circumstellar Dust Shells.- 2.5.5. Summary.- 2.6. Mass Loss Mechanisms for Late-Type Giants and Supergiants.- 2.6.1. Overview.- 2.6 2. Thermally Driven Winds.- 2.6.3. Radiation Driven Winds.- 2.6.4. Wave Driven Winds 88 3. The Winds and Coronae of Early-Type Stars.- 3.1. Introduction.- 3.2. The Velocity and Mass Loss Rates Derived from Line and Continuum Observations.- 3.2.1. The Formation of P Cygni Profiles.- 3.2.2. The Free-Free Continuum Energy Distribution of Hot Stars.- 3.3. Coronal Gas in Early-Type Stars.- 3.3.1. Superionization of the Winds.- 3.3.2. X-Ray Observation of Early-Type Stars.- 3.4. Wind Dynamics.- 3.4.1. Radiation Forces on Line Opacity: Momentum Deposition Considerations.- 3.4.2. Radiative Acceleration.- 3.4.3. Instability of Line Driven Winds and the Consequences.- 3.4.4. Hybrid Models with a Base Coronal Zone.- 3.4.5. Magnetically Driven Winds and Magnetically Dominated Coronae.- Acknowledgements.- References.- 19: Solar and Stellar Magnetic Activity.- 1. Introduction.- 2. Solar and Stellar Magnetic Activity: A Phenomenological Comparison.- 2.1. Surface Magnetic Fields and their Effects on Stellar Radiative Flux.- 2.2. Direct Detection of Magnetic Fields on Stars Like the Sun.- 2.3. Ca II H and K Emission as Indicators of Stellar Magnetic Fields.- 2.4. Coronal Active Regions.- 2.5. Magnetic Activity Cycles.- 3. The Rotation/Activity/Age Connection.- 3.1. The Aging of Magnetic Activity and Rotation.- 3.2. Rotation as the Fundamental Determinant of Magnetic Activity.- 3.3. The Influence of Convection Zone Properties.- 3.4. The Vaughan-Preston Gap.- 3.5. The Evolution of Rotation and Magnetic Activity on the Sun.- 4. Avenues for Future Research.- 4.1. Observational Studies of Solar Magnetic Activity.- 4.2. Observational Studies of Stellar Magnetic Activity.- 4.3. Theoretical Studies.- Acknowledgements.- References.- 20: Effects of Solar Electromagnetic Radiation on the Terrestrial Environment.- 1. Introduction.- 2. Atmospheric Structure and Composition.- 2.1. Thermosphere.- 2.2. Stratosphere and Mesosphere Structure.- 2.3. Stratosphere and Mesosphere Chemistry.- 2.4. Tropospheric Chemistry.- 3. The Climate System.- 3.1. Current Questions.- 3.2. Introduction to Simple Climate Models.- 3.3. Tapping of Thermal Radiation by Atmospheric Constituents.- 3.4. Thermal Feedback by Clouds and Water Vapor.- 3.5. Anthropogenic Modulation of Trace Gases Important for Climate.- 3.6. Atmospheric and Oceanic Circulation and the Seasons.- 3.7. Primitive Climate, the Carbon Cycle and the Faint-Early-Sun.- 4. Solar Radiation Drives the Biosphere.- 4.1. Origins of Photosynthesis.- 4.2. Photosynthesis in Action.- 4.3. Harvesting the Sunlight, Net Primary Productivity.- 5. Concluding Remarks.- Acknowledgements.- References.- 21: The Effect of the Solar Wind on the Terrestrial Environment.- 1. Introduction.- 2. General Morphology.- 3. Solar Wind and Geomagnetic Activity.- 3.1. Solar Wind Streams.- 3.2. Geomagnetic Response to Streams.- 3.3. Periodic Geomagnetic Activity.- 3.3.1. Geomagnetic Pulsations.- 3.3.2. Diurnal and Annual Variations.- 3.3.3. Solar Cycle and Longer Period Variations.- 4. Transfer Mechanisms at the Magnetopause.- 4.1. Magnetic Merging.- 4.2. Other Mechanisms.- 4.3. Composite Model.- 5. Magnetospheric Convection.- 5.1. Convection Morphology.- 5.2. Birkeland Currents, Alfvén Layers, and Shielding.- 5.3. The Plasmasphere: a Convection/Corotation Forbidden Zone.- 5.4. Time Dependent Convection - The Substorm Cycle.- 5.5. Computer Modeling of Convection.- 5.6. Convection and Magnetic Merging in the Magnetotail.- 6. Magnetosphere Effects on the Ionosphere and Thermosphere.- 6.1. Low-Latitude Electric Fields and Currents.- 6.2. Parallel Electric Fields.- 6.3. Ionospheric Outflow.- 6.4. Effects on Thermosphere.- 7. Middle and Lower Atmosphere.- Acknowledgement…