The space age, with lunar missions and interplanetary probes, has revolutionized our understanding of the Solar system. Planets and large moons, which previously appeared in telescopes only as fuzzy disks, have become familiar worlds, with a range of diverse properties. Large numbers of asteroids, comets and small moons have now been discovered, and many of these objects studied in detail. Indeed, the number of planets now known to orbit stars other than our Sun far exceeds those within our own solar system. As a result, our understanding of the process of star and planet formation is increasing all the time. Planetary sciences presents a comprehensive coverage of this fascinating and expanding field at a level appropriate for graduate students and juniors and seniors majoring in the physical sciences. The book explains the wide variety of physical, chemical and geological processes that govern the motions and properties of planets. Observations of the planets, moons, asteroids, cornets and planetary rings in our solar system, as well as extrasolar planets, are described and the process of planetary formation is discussed. This text will be used by graduate students and researchers in astronomy, planetary science and earth science.