The last few decades have been called the Golden Age of Astronomy . The rapid increase of knowledge in the field necessitates publishing a new edition of the Astronomy and Astrophysics volumes of the Landolt-Boernstein. The title is now Astronomy, Astrophysics, and Cosmology . Cosmology has been added in order to make allowances for the increasing role of extragalactic astrophysics and cosmology. The present volume VI/4B on the Solar System is the first to be published of the new series. Volume VI/4A on Instruments and Methods will follow soon. Additional volumes on Stars , the Galaxy , Galaxies, Large Scale Structure and Cosmology are in the planning stage. The previous volumes covering the Solar System appeared in 1965, 1981 and 1993. In the meantime multi-wavelength observations of the sun - by ground based and space borne telescopes - have produced a wealth of new data. The same is true for telescopic and/or in situ investigations of the planets, moons, asteroids, meteors, meteorites, interplanetary dust, solar wind etc. The use of units for physical quantities in the present volume follows largely the rules given by the International Astronomical Union (IAU), c.f. http://www.iau.org/science/publications/proceedings/\_rules/units/, which favour the international system (SI) of units. However, the centimetre-gram-second (CGS) system is used in some sections of the present volume, since it is still dominating in certain areas of astrophysics. A table with unit conversion of CGS to SI is given on the inside of the back cover of this book.