This astronomy course forms an introduction to planetary science, the study of planetary systems. Astronomy is presented as a way to understand our origins and place in the universe. Some of the scientific and technological tools used in astronomy are then discussed, as a prelude to a review of our knowledge of the planets orbiting our Sun, and extrasolar planets orbiting other stars. Earth is recognised as a small terrestrial world among the many planets orbiting our star and others, and the history of our planetary system is traced from a cloud of gas and dust through to the diversity of large and small worlds we observe today. The course includes discussion of the geology and atmospheres of the terrestrial planets, jovian planet systems, and the interplanetary bodies of our solar system. Extrasolar planet studies are presented as an emerging research field transforming planetary science. Mt Kent Observatory is also made available to students enrolled in this course, to provide an opportunity for learning technical skills in observational astronomy. This course complements PHY1107 Astronomy 2, an introduction to the Sun, the stars and galaxies.