Giants of Gas and Ice

Abstract

Immediately beyond the orbit of Mars lies a wide gulf uninhabited by any major planet. It is, however, the abode of a great number of smaller sub-planetary bodies known as “asteroids,” about which more shall be said in the following chapter. Further beyond this region, extending to the very edges of the system of major planets, lies the realm of the giant orbs Jupiter, Saturn, Uranus and Neptune. The first two are known as “gas giants” and take us to the limits of the Solar System known to astronomers before the late 1700s. The remaining more modestly proportioned worlds—the “ice giants”—were unknown to the ancients and by comparison with the worlds discussed in the previous chapter of this book are very, very far away.