The Photosphere of the Sun.- I. The continuous spectrum.- a) Solar constant.- b) Observed limb darkening.- c) Observed solar energy distribution.- d) Observational models of the photosphere.- II. The Fraunhofer spectrum.- a) Observational data.- b) The formation of Fraunhofer lines.- c) The analysis of Fraunhofer lines.- General references.- Structure and Dynamics of the Solar Atmosphere.- A. The undisturbed photosphere and chromosphere.- I. The undisturbed photosphere.- a) Granulation.- b) Temperature and density inhomogeneities in the photosphere.- c) Micro- and macro-turbulence in the photosphere.- d) Theory of convection and turbulence in the solar atmosphere.- II. The chromosphere.- a) The chromosphere at the limb.- b) The chromosphere on the disk.- c) Structure and dynamics of the chromosphere; transition to the corona.- B. The disturbed parts of the photosphere and chromosphere.- I. Sunspots.- a) The individual spots.- b) Group of spots.- II. Photospheric and chromospheric faculae.- a) The faculae proper.- b) The "centre of activity".- III. Flares and associated phenomena.- a) Monochromatic observations.- b) Spectrographic observations.- c) Dynamical phenomena associated with flares.- IV. Filaments and prominences.- a) The quiescent prominences.- b) Moving prominences.- C. The corona.- I. Optical observations.- a) The quiet minimum corona; photometry, ionization and excitation.- b) The structure of the quiet minimum corona; temperatures and densities.- c) The active parts of the corona and the "maximum corona".- II. Radio emission from the Sun.- a) The quiet Sun.- b) Thermal radiation from centres of activity.- c) Non-thermal radiation: type III and type U bursts.- d) Other non-thermal radiophenomena, often connected with flares.- D. Solar rotation and the solar cycle.- a) The solar cycle.- b) Solar rotation and the Sun's general magnetic field.- E. Solar and terrestrial relationship.- General references.- The Atmospheres of the Planets.- I. Introduction.- II. The Earth's atmosphere.- III. The atmosphere of Venus.- IV. The atmosphere of Mars.- V. The atmospheres of Mercury and the Moon.- VI. The atmospheres of major planets and their satellites.- VII. Conclusions.- Acknowledgment.- References.- Planetary Interiors.- I. The mass-radius relation of cold bodies.- II. Empirical features of the planets.- III. Structure and composition of the planets.- a) The constitution of the terrestrial planets.- b) The constitution of the jovian planets.- Radio Echoes from Sun, Moon and Planets.- I. Strength and characteristics of echoes.- II. Moon echoes.- III. Future possibilities.- IV. The Earth's immediate neighbourhood.- General references.- Die Kometen.- I. Einleitung.- II. Kometenbahnen.- III. Spektren und Physik der Kometen.- IV. Zur Deutung der Kometenformen.- V. Kosmogonie der Kometen.- Meteors.- 1. Introduction.- 2. Basic theory of the meteoric processes.- 3. Meteor spectra.- 4. Meteor dynamics and orbits of comets, asteroids, and meteors.- 5. Meteoritic dust.- 6. Visual meteor studies.- 7. Radio meteor techniques.- 8. Photographic meteor techniques.- 9. The masses and densities of meteoroids.- 10. Shower meteors.- 11. Sporadic meteors and the total influx.- 12. Origin of meteors, fireballs and meteorites.- 13. Meteorites.- Acknowledgments.- Sachverzeichnis (Deutsch/Englisch).- Subject Index (English/German).