Chapter 8 B

Which of the following best describes the nature of planetary rings?

They are composed of countless individual particles.

Orbital resonance also gives Europa an elliptical orbit, so it experiences tidal heating, too. However, Europa experiences less tidal heating than Io, because Europa __________ than Io.

is farther from Jupiter

Io experiences tidal heating primarily because __________.

its elliptical orbit causes the tidal force to vary as Io orbits Jupiter.

Saturn's rings look bright because __________.

light from the Sun reflects off the material in the rings

Saturn's rings are composed of __________.

lots of individual particles of ice and rock

Match the words in the left-hand column to the appropriate blank in the sentences in the right-hand column. Use each word only once.

1. The largest moon in the solar system is *Ganymede. 2. The jovian moon with the most geologically active surface is *Io. 3. Strong evidence both from surface features and magnetic field data support the existence of a subsurface ocean on *Europa. 4. *Tidal heating is responsible for the tremendous volcanic activity on Io. 5. *Callisto is the most distant of Jupiter's four Galilean moons. 6. The fact that Europa orbits Jupiter twice for every one orbit of Ganymede is an example of a(n) *orbital resonance.

Using the data in the table Satellites of the Solar System, identify the orbital resonance relationship between Titan and Hyperion. (Hint: If the orbital period of one were 1.5 times the other, we would say that they are in a 3:2 resonance.)

4 : 3

Io is shown in the figure below. (Left: approximate colors of Io in visible light; black spots are volcanoes that are still active or have recently gone inactive. Right: infrared thermal emission from Io; the bright spots are active volcanoes.) 1. What do the colors represent in the right image? 2. Which color in the right image indicates regions with the highest temperature? 3. The right image was obtained when only part of Io was in sunlight.Based on the colors, which part of the surface was in sunlight? 4. By comparing the two images, what can you conclude about Io's volcanoes?

1. the intensity of the infrared light 2. white 3. the right side 4. There are more black spots in the visible image than bright spots in the infrared image, so many of Ios volcanoes were inactive when the photos were taken.

Which medium-size moon is in a 2:1 resonance with Enceladus?

Dione

Which moon is considered likely to have a deep, subsurface ocean of liquid water?

Europa

Listed following are some of the distinguishing characteristics of the four Galilean moons of Jupiter. Match each characteristic to the appropriate moon.

Io hot, glowing lava visible in some photossource of ionized gas in the donut-shaped charged particle belt around Jupitervolcanoes currently erupting Europa double-ridged surface features strongly suggest a subsurface ocean belowice covered surface with few impact craters Ganymede heavily cratered terrain adjacent to fairly smooth terrainlargest moon in the solar system Callisto entire surface appears heavily cratered and ancient most distant from Jupiter of these four moons

Why is Io more volcanically active than our moon?

Io has a different internal heat source.

As you saw in Part A, Io's elliptical orbit is necessary to its tidal heating. This elliptical orbit, in turn, is a result of the orbital resonance among Io, Europa, and Ganymede. This orbital resonance causes Io to have a more elliptical orbit than it would otherwise, because __________.

Io, Europa and Ganymede periodically return to the same orbital positions, creating the same gravitational tugs

Which statement about Io is true?

It is the most volcanically active body in our solar system.

What is unusual about Triton?

It orbits its planet backward.

Match the words at the left to the correct blanks in the sentences at right.

Jupiter has three moons for which there is evidence of a global, subsurface ocean of liquid water, with the strongest evidence favoring an ocean on *Europa*. *Io* is the most volcanically active world in the solar system. Scientists have detected lakes of liquid methane and ethane on the surface of *Titan*. Spacecraft images show fountains of ice spraying into space from Saturn's moon *Enceladus*. The two moons that are larger than the planet Mercury are Titan and *Ganymede*, which is also the largest of Jupiter's moons (and largest moon in the solar system).

What is the ratio of Titan's mass to that of all the other satellites of Saturn whose masses are listed in Appendix E?

MTitan / Mothermoons = 23.2

Which of the following statements about the moons of the jovian planets is NOT true?

Most of the moons are large enough to be spherical in shape, but a few have the more potato-like shapes of asteroids. true: -One of the moons has a thick atmosphere. -Some of the moons are big enough that we'd call them planets (or dwarf planets) if they orbited the Sun. -Many of the moons are made largely of ices.

Which of the following statements correctly describes the motion of the particles in Saturn's rings?

Particles in the inner rings orbit Saturn at a faster speed than particles in the outer rings.

Which moon has a thick atmosphere made mostly of nitrogen?

Titan

Which moon shows evidence of rainfall and erosion by some liquid substance?

Titan

Compare the satellites' ability to retain an atmosphere.

Titan's ability to retain an atmosphere is much higher than Mimas's.

The two jovian planets that contain the highest proportions of hydrogen compounds are ___________.

Uranus and Neptune

We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. What observational evidence confirms that tidal heating is important on Io?

active volcanoes on Io

We now know of many Jupiter-size planets around other stars. Suppose that future observations show that one of these planets has two orbiting moons. What additional information, if any, would we need to decide whether these moons experience tidal heating?

We need to know their orbital periods.

Saturn's rings

are continually supplied by impacts with small moons.

Suppose you could float in space just a few meters above Saturn's rings. What would you see as you looked down on the rings?

countless icy particles, ranging in size from dust grains to large boulders

Calculate the strength of gravity on Titan compared to that on Mimas.

gTitangMimas = 21.8

The main ingredients of most satellites of the jovian planets are

hydrogen compound ices.

Saturn's many moons affect its rings through

orbital resonances.