(Background) Through the cameras onboard the Hubble Space Telescope, the planet Saturn appears much as our naked eyes would see it if it were only six times as far away as the Moon. Resolution here is 670 km, good enough to see clearly the band structure on the ball of the planet, as well as several gaps in the rings. True-color images like this one are made by combining separate images taken in red, green, and blue light, as shown in the inserts.

(Inset A) Saturn as seen through a red filter, centered at a wavelength of 718 nm.

(Inset B) Saturn as seen through a green filter, centered at a wavelength of 547 nm.

(Inset C) Saturn as seen through a blue filter, centered at a wavelength of 439 nm.

LEARNING GOALS

Studying this chapter will enable you to:

Summarize the orbital and physical properties of Saturn, and compare them with those of Jupiter.

Describe the composition and structure of Saturn's atmosphere and interior.

Explain why Saturn's internal heat source and magnetosphere differ from those of Jupiter.

Describe the structure and composition of Saturn's rings.

Define the Roche limit and explain its relevance to the origin of Saturn's rings.

Summarize the general characteristics of Titan and discuss the chemical processes in its atmosphere.

Discuss some of the orbital and geological properties of Saturn's smaller moons.

Saturn is one of the most beautiful and enchanting of all astronomical objects. Its rings are a breathtaking sight when viewed through even a small telescope, and they are probably the planet's best-known feature. Aside from its famous rings, however, Saturn presents us with another good example of a giant gaseous planet. Saturn is in many ways similar to its larger neighbor, Jupiter, in terms of composition, size, and structure. Yet when we study the two planets in detail, we find that there are important differences as well. A comparison between Saturn and Jupiter provides us with valuable insight into the structure and evolution of all the jovian worlds.