323
CHAPTER
12
Jupiter (left) and Saturn (right) to scale. R I V U X G
Jupiter and Saturn: Lords of the Planets
LEARNING GOALS
By Reading The Sections Of This Chapter, You Will Learn
| 12–1 | What observations from Earth reveal about Jupiter and Saturn |
| 12–2 | How Jupiter and Saturn rotate differently from terrestrial planets like Earth |
| 12–3 | The nature of the immense storms seen in the clouds of Jupiter and Saturn |
| 12–4 | How the internal heat of Jupiter and Saturn drives activity in their atmospheres |
| 12–5 | What the Galileo space probe revealed about Jupiter’s atmosphere |
| 12–6 | How the shapes of Jupiter and Saturn indicate the sizes of their rocky cores |
| 12–7 | How Jupiter and Saturn’s intense magnetic fields are produced by an exotic form of hydrogen |
| 12–8 | The overall structure and appearance of Saturn’s ring system |
| 12–9 | What kinds of particles form the rings of Jupiter and Saturn |
| 12–10 | How spacecraft observations revealed the intricate structure of Saturn’s rings |
| 12–11 | How Saturn’s rings are affected by the presence of several small satellites |
Among the most remarkable sights in our solar system are the colorftul, turbulent atmosphere of Jupiter and the ethereal beauty of Saturn’s rings. Both of these giant worlds dwarf our own planet: More than 1200 Earths would fit inside Jupiter’s immense bulk, and more than 700 Earths inside Saturn. Unlike Earth, both Jupiter and Saturn are composed primarily of the lightweight elements hydrogen and helium, in abundances very similar to those in the Sun.
As these images show, the rapid rotations of both Jupiter and Saturn stretch their weather systems into colorful bands that extend completely around each planet. Both planets also have intense magnetic fields that are generated in their interiors, where hydrogen is so highly compressed that it becomes a metal.
Saturn, however, is not merely a miniature version of Jupiter. Its muted colors and more flattened shape are clues that Saturn’s atmosphere and interior have important differences from those of Jupiter. The most striking difference is Saturn’s elaborate system of rings, composed of countless numbers of icy fragments orbiting in the plane of the planet’s equator. The rings display a complex and elegant structure, which is shaped by subtle gravitational influences from Saturn’s retinue of moons. Jupiter, too, has rings, but they are made of dark, dustlike particles that reflect little light. These systems of rings, along with the distinctive properties of the planets themselves, make Jupiter and Saturn highlights of our tour of the solar system.
324