This book may serve to present the modern view of the universe to a large number of readers whose over-full professional commit­ ments leave them no time for the study of larger monographs ... Such a book should not be too compendious. Accordingly, the author has been at pains to allow the leading ideas of the various domains of astronomical investigation to stand out plainly in their scientific and historical settings; the introductory chapters of the three parts of the book ... , in the framework of historical surveys, should assist the general review. With that in mind, the title was chosen following Alexander von Humboldt's well known book "Kosmos, Entwurf einer physischen Weltbeschreibung" (1827-1859). On the other hand, particular results - which admittedly first lend colour to the picture - are often simply stated without attempting any thorough justification. The reader seeking further information will find guidance in the Bibliography. This makes no pretentions to completeness or historical balance. References in the text or in captions for the figures, by quoting authors and years, make it possible for the reader to trace the relevant publications through the standard abstracting journals. I wish to thank my colleagues V. WEIDEMANN, E. RICHTER and B. BASCHEK for their critical reading of the book and for much helpful counsel, and H. HOLWEGER for his tireless collaboration with the proofs. Similarly, my thanks are due to Miss ANTJE WAGNER for the careful preparation of the typescript.

Inhalt

I Classical Astronomy.- 1. Stars and Men: Observing and Thinking. Historical Introduction to Classical Astronomy.- 2. Celestial Sphere: Astronomical Coordinates: Geographic Latitude and Longitude.- 3. Motion of the Earth: Seasons and the Zodiac: Day, Year and Calendar.- 4. Moon: Lunar and Solar Eclipses.- 5. Planetary System.- 6. Mechanics and Theory of Gravitation.- 7. Physical Constitution of Planets and Satellites.- 8. Comets, Meteors and Meteorites, Interplanetary Dust; Structure and Composition.- Interlude.- 9. Astronomical and Astrophysical Instruments.- II Sun and Stars: Astrophysics of Individual Stars.- 10. Astronomy + Physics = Astrophysics. Historical Introduction.- 11. Radiation Theory.- 12. The Sun.- 13. Apparent Magnitudes and Colour Indices of Stars.- 14. Distances, Absolute Magnitudes and Radii of the Stars.- 15. Classification of Stellar Spectra: Hertzsprung-Russell Diagram and Colour-Magnitude Diagram.- 16. Double Stars and the Masses of the Stars.- 17. Spectra and Atoms: Thermal Excitation and Ionization.- 18. Stellar Atmospheres: Continuous Spectra of the Stars.- 19. Theory of Fraunhofer Lines: Chemical Composition of Stellar Atmospheres.- 20. Motions and Magnetic Fields in the Solar Atmosphere: Solar Cycle.- 21. Variable Stars: Motions and Magnetic Fields in Stars.- III Stellar Systems: Milky Way and Galaxies: Cosmogony and Cosmology.- 22. Advance into the Universe. Historical Introduction to Astronomy in the Twentieth Century.- 23. Constitution and Dynamics of the Galactic System.- 24. Interstellar Matter.- 25. Internal Constitution and Energy Generation of Stars.- 26. Colour-Magnitude Diagrams of Galactic and Globular Clusters Stellar Evolution and Abundances of the Elements.- 27. Galaxies.- 28. Radio Emission from Galaxies: Exploding Galaxies.- 29. Cosmic Rays: High Energy Astronomy.- 30. Cosmology.- 31. Origin of the Solar System: Evolution of the Earth and of Life.- Stellar Populations in the Galaxy.- Physical Constants and Astronomical Quantities.- Figures: Acknowledgments.