The atmospheres of the outer planets

Abstract

Beyond the asteroid belt lie the giant planets, Jupiter, Saturn, Uranus and Neptune and their extensive satellite systems, and Pluto, which is more like a satellite than any of its giant companions. Those large planets are huge, rapidly rotating bodies and seem to Ibrm two separate families.Jupiter and Saturn appear to have an apparently permanently banded appearance of alternating light and dark clouds of rapidly changing colours. The composition of their atmospheres seems to be similar to that of the Sun. Present theories are unable to account for the banded structure, the origin of the colours and the Great Rod Spot situated in the southern Jovian hemisphere. These planets are surrounded by an extensive system of 23 satellites. Two of them, Io of the Galilean satellites, and Titan of the Saturnian system, have atmospheres. The Titan atmosphere is thought to be considerably larger than the present Martian atmosphere.Uranus and Neptune are thought to form a separate family of planets, with less than solar proportions of the light elements, and larger portions of methane than found on Jupiter and Saturn.In this article, which was completed in March 1976, we review our current understanding of the atmospheres of the major planets. CONTENTS