Chapter 11 Astronomy
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 statement about planetary rings is not true?
Saturn's rings formed along with its moons 4.6 billion years ago.
Which planet may have helium rain in its interior, and what does this rain do?
Saturn, where it generates heat as it falls downward.
Which of the following best explains why we see horizontal "stripes" in images of Jupiter and Saturn?
The light stripes are regions of high clouds, and the dark stripes are regions where we can see down to deeper, darker clouds.
Which statement about Saturn's rings is not true?
The rings must look much the same today as they did shortly after Saturn formed.
Why does Jupiter have three distinct layers of clouds?
The three layers represent clouds made of gases that condense at different temperatures.
Look at the average densities of the jovian planets given in the figure. Can you identify a trend in jovian planet densities with mass or distance from the Sun?
There is no clear trend in the densities with mass or distance
Which of the following statements comparing the jovian interiors is not thought to be true?
They all have the same exact set of internal layers, though these layers differ in size.
Which of the following best describes the nature of planetary rings?
They are composed of countless individual particles.
Which of the following statements best explains why the densities of Uranus and Neptune are higher than that of Saturn, even though Saturn is much more massive?
They have a higher proportion of hydrogen compounds and rock.
What is the relevance of tidal heating to the possibility of life on jovian moons?
Tidal heating can lead to subsurface zones of liquid water.
Which moon shows evidence of rainfall and erosion by some liquid substance?
Titan
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. Scientists have detected lakes of liquid methane and ethane on the surface of Titan. Io is the most volcanically active world in the solar system. 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).
Uranus and Neptune
Which of the following statements best describes the general pattern of composition among the four jovian planets?
Uranus and Neptune contain relatively more rock and hydrogen compounds than Jupiter and Saturn.
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.
What is tidal heating?
a source of internal heat caused by varying tidal forces acting on a moon or other object
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
In light of what we know about geological activity on the terrestrial worlds, why might it seem surprising to find geological activity on jovian moons?
because they are relatively small in size
The energy in the atmospheres of most of the jovian planets comes ___________.
both the Sun and their interiors, with both contributing significantly
Which of the following best describes the internal layering of Jupiter, from the center outward?
core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer
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
Based on what you learn about jovian moons by watching the videos or reading your textbook, what types of evidence for recent or ongoing geological activity have been observed on one or more jovian moons?
ice crystals being sprayed out into space active volcanoes surfaces with very few impact craters river valleys feeding into surface lakes of very cold liquids
Which of the following can contribute to explaining why jovian moons are sometimes much more geologically active than terrestrial worlds of similar (or smaller) size?
ice-rich composition tidal heating
Io experiences tidal heating primarily because __________.
its elliptical orbit causes the tidal force to vary as Io orbits Jupiter.
Which of the following is most unlikely to be found on Titan?
lakes of liquid water in the warmer equatorial regions
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
The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their mass, from lowest to highest. (Not to scale.)
lowest to highest mass earth uranus neptune saturn jupiter
Saturn's many moons affect its rings through
orbital resonances.
The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their size (average equatorial radius), from smallest to largest. (Not to scale.)
smallest to largest radius earth neptune uranus saturn jupiter
Based on the leading scientific theory of solar system formation, which of the following statements best explains why Uranus and Neptune have a significantly different composition than Jupiter and Saturn?
Jupiter and Saturn captured more gas from the solar nebula than Uranus and Neptune
Which of the following most likely explains why Jupiter's interior releases so much heat?
Jupiter is gradually contracting in size
Which of the following best explains why Jupiter's density is higher than Saturn's?
Jupiter is more massive than Saturn.
Which of the following statements about the moons of the jovian planets is true?
Most of the moons have the potato-like shapes of asteroids, but a few are large enough to be spherical in shape.
closest to farthest from the sun
a typical asteroid belt kuiper oort cloud
What major feature of Saturn's moon Enceladus led scientists to suspect it might have a subsurface ocean?
fountains of ice spraying out from the surface into space
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
This painting shows an artist's conception of what it would look like to be within Saturn's system of rings. Notice the many whitish "balls" visible in this painting. Based on what you have learned about rings, about how large are each of these "balls," on average?
About a size that you could hold in your arms.
Why is Io more volcanically active than our moon?
Io has a different internal heat source.
All the following statements are true. Which one is most important in explaining the tremendous tidal heating that occurs on Io?
Io orbits Jupiter on an elliptical orbit as a result of orbital resonances with other moons.
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
What is unusual about Triton?
It orbits its planet backward.
What would happen to Jupiter if we could somehow double its mass?
Its density would increase, but its diameter would barely change.
