ASTRONOMY CHAPTER 11
Saturn's many moons affect its rings through
orbital resonances
Which of the following is not due to tidal forces? the synchronous rotation of the Moon around Earth the volcanos on Io (a moon of Jupiter) the grooved terrain of Enceladus (a moon of Saturn) the rings of Saturn the backward orbit of Triton (a moon of Neptune)
the backward orbit of Triton (a moon of Neptune)
Why do astronomers believe that Triton is a captured moon?
Triton orbits Neptune in a direction opposite that of Neptune's rotation.
Jupiter likely formed first since it is the largest jovian planet and closest to the Sun.
True
Which of the following gases is not a significant ingredient of the jovian planet atmospheres? carbon dioxide hydrogen water helium
carbon dioxide
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
what types of evidence for recent or ongoing geological activity have been observed on one or more jovian moons? Select all that apply. river valleys feeding into surface lakes of liquid water ice crystals being sprayed out into space active volcanoes large, violent storms swirling in counterclockwise directions river valleys feeding into surface lakes of very cold liquids surfaces with very few impact craters
ice crystals being sprayed out into space active volcanoes river valleys feeding into surface lakes of very cold liquids surfaces with very few impact craters
What causes synchronous rotation?
A massive planet exerts a tidal force on a moon that causes the moon to align itself such that its tidal bulges always point toward and away from the planet.
Why are Saturn's rings so thin?
Any particle in the ring with an orbital tilt would collide with other ring particles, flattening its orbit.
Which of the following is not a piece of evidence supporting the idea that Europa may have a subsurface ocean? Europa's surface shows few impact craters. Astronomers have detected small lakes of liquid water on Europa's surface. Europa has a magnetic field that appears to be induced by Jupiter's magnetic field. Photos of Europa's surface show regions that appear to consist of jumbled icebergs frozen in place.
Astronomers have detected small lakes of liquid water on Europa's surface.
Why do we think that ring particles must be replenished over time? Where we think ring particles come from?
Because collisions are constantly occurring within the ring systems, ring particles are continually being ground down to dust. Dust cannot survive long in ring systems because sunlight pressure makes the particles slowly fall onto the planet. So we think that ring systems cannot survive very long and thus that ring particles must be replenished, probably by impacts on small embedded moons and ring particles by micrometeorites and the occasional larger impacts.
How might its capture be relevant to its geological activity?
Even though Triton is much smaller than our Moon, Triton' surface shows evidence of relatively recent geological activity. This can be because of the tidal heating that occurred when the moon was captured.
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 is the closest to Jupiter of Jupiter's large moons. Io orbits Jupiter in the Io torus, and therefore has a surface that is bombarded by many charged particles. Io exhibits synchronous rotation, meaning that its rotation period and orbital period are the same. Io orbits Jupiter on an elliptical orbit as a result of orbital resonances with other satellites.
Io orbits Jupiter on an elliptical orbit as a result of orbital resonances with other satellites.
Why do we think Triton is a captured moon? Check all that apply. It orbits Neptune at a very low inclination to Neptune's equator. It orbits Neptune in the direction of Neptune's rotation. It orbits Neptune at a high inclination to Neptune's equator. It orbits Neptune in the direction opposite to Neptune's rotation.
It orbits Neptune at a high inclination to Neptune's equator. It orbits Neptune in the direction opposite to Neptune's rotation.
What would happen to Jupiter if we could somehow double its mass?
Its density would increase, but its diameter would barely change.
Which of the following best explains why many jovian moons have been more geologically active than the Moon or Mercury? Because of their greater distances from the Sun, the jovian moons receive much less heat from the Sun. The jovian moons probably have far more internal heat generated by radioactive decay than do the Moon or Mercury. Jovian moons are made mostly of ice that can melt or deform at lower temperatures than can the rock and metal that make up the Moon and Mercury. The jovian moons are considerably larger than the Moon and Mercury and therefore have retained much more internal heat.
Jovian moons are made mostly of ice that can melt or deform at lower temperatures than can the rock and metal that make up the Moon and Mercury.
Which of the following most likely explains why Jupiter's interior releases so much heat? A slow rate of nuclear fusion in Jupiter's core. Heat from radioactive decay. Jupiter is contracting gradually. Tidal heating.
Jupiter is contracting gradually
Which of the following statements correctly describes the motion of the particles in Saturn's rings? Particles in all the rings hover motionlessly high above Saturn. Particles in the inner rings orbit Saturn at a faster speed than particles in the outer rings. Particles in the inner rings orbit Saturn at a slower speed than particles in the outer rings. All the particles in the rings orbit Saturn with the same orbital period.
Particles in the inner rings orbit Saturn at a faster speed than particles in the outer rings.
According to our theory of solar system formation, why did Uranus and Neptune end up to be much less massive than Jupiter and Saturn?
Particles in the solar nebula were more spread out at greater distances, so that accretion took longer and there was less time to pull in gas before the solar wind cleared the nebula.
which planet may have helium rain in its interior, and what does this rain do?
Saturn, where it generates heat as it falls downward.
Uranus and Neptune have methane clouds but Jupiter and Saturn do not. Which factor explains why?
Temperatures on Jupiter and Saturn are too high for methane to condense.
Which of the following best explains why we see horizontal "stripes" in photographs of Jupiter and Saturn? There are three different color stripes corresponding to the three different types of clouds found on these planets. Dark stripes are those in which there is a stratosphere and light stripes are those with no stratosphere. The light stripes are regions of high clouds, and the dark stripes are regions where we can see down to deeper, darker clouds. The dark and light stripes correspond to alternating bands of different chemical composition.
The light stripes are regions of high clouds, and the dark stripes are regions where we can see down to deeper, darker clouds.
Why is the radiation so intense in the region that traces Io's orbit around Jupiter (the Io torus)?
The region is full of gases that become ionized after they are released from volcanoes on Io.
Which statement about Saturn's rings is not true? Some features of the rings are shaped by small moons that actually orbit within the ring system. The rings are so thin that they essentially disappear from view when seen edge-on. The large gap known as the Cassini Division is shaped by an orbital resonance with the moon Mimas, which orbits well outside the rings. The rings must look much the same today as they did shortly after Saturn formed.
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.
Jupiter and the other jovian planets are sometimes called "gas giants." In what sense is this term misleading?
They actually contain relatively little material in a gaseous state.
Which of the following best describes the nature of planetary rings? The are solid, concentric rings around a planet. They are composed of reflective molecules of gas. They are composed of countless individual particles. They are a solid sheet of material around a planet, looking much like a DVD or blu-ray disk.
They are composed of countless individual particles.
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? Select all the factors that contribute. tidal heating orbiting far from the Sun orbiting far from their planet having a core of metal and rock ice-rich composition
Tidal heating ice-rich composition
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
Which jovian planet should have the most extreme seasonal changes?
Uranus
The two jovian planets that contain the highest proportions of hydrogen compounds are ___________.
Uranus and Neptune
What is the Cassini division of Saturn's rings?
a large gap, visible from Earth
Saturn's rings
are continually supplied by impacts with small moons.
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
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 methane or ethane lakes of liquid water in the warmer equatorial regions volcanic outgassing of methane and other gases rain or snow consisting of methane or ethane droplets or ice crystals
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
