Deck 11: Planetary Moons and Rings

Question 1

On which of Saturn's moons did the Cassini-Huygens Probe land in 2004, providing our first view of the varied and active surface?

A) Callisto
B) Io
C) Europa
D) Enceladus
E) Titan

Answer 1

Titan

Question 2

By studying the orbit of a moon around its parent planet, astronomers can use ________ to find the parent planet's ________.

A) escape velocity; rotation rate
B) the moon's eccentricity; Roche limit
C) small perturbations; magnetic field strength
D) the moon's velocity; radius
E) Newton's version of Kepler's third law; mass

Answer 2

Newton's version of Kepler's third law; mass

Question 3

Most large regular moons probably formed

A) when passing asteroids were captured by the gravitational field of their planet.
B) at the same time as their planets and grew by accretion.
C) after a collision between a planet and a large asteroid fractured off a piece of the planet.
D) after the period of heavy bombardment in the early Solar System.
E) after a planet got kicked out of its orbit and was gravitationally captured by another planet.

Answer 3

at the same time as their planets and grew by accretion.

Question 4

The only planet(s) without a moon is (are)

A) Mercury only.
B) Venus only.
C) Mars only.
D) Mercury and Venus.
E) Mercury, Venus, and Mars.

Question 5

If a moon has a retrograde orbit, then it orbits

A) in the direction opposite that of the planet's rotation.
B) in the opposite direction than its planet revolves around the Sun.
C) the Sun at a greater distance than the planet.
D) with an unusually high velocity.
E) None of these is true.

Question 6

Based on the figure below, this moon

A) is geologically active.
B) is possibly geologically active.
C) was geologically active in the past but is no longer active.
D) is geologically dead.
E) More information is needed before any conclusion can be made.

Question 7

Why are some moons such as Io and Enceladus geologically active even though they are small in size compared to the planets?

A) Unlike some planets, these moons have additional supplies of radioactive elements providing the necessary heating to drive geological activity.
B) The interiors of these moons contain a larger supply of heavy elements such as iron than is found in terrestrial planets, which contributes to greater heating and high geological activity.
C) Tidal forces from the Sun are especially large for these moons, leading to greater interior heating and more geological activity.
D) Tidal forces from the parent planet heat the interiors of these moons, resulting in geological activity.
E) None of these; it is still a mystery.

Question 8

Assume that we discover a new moon of Jupiter.It orbits Jupiter at a large distance and in the opposite direction that Jupiter rotates.It is much smaller than most of Jupiter's other moons
And has a density close to that of Earth rocks.Therefore, this moon is most likely

A) a regular moon that formed with Jupiter in the early Solar System.
B) an irregular moon that is most likely a captured asteroid.
C) an irregular moon that is most likely a captured comet.
D) an irregular moon that is most likely a protoplanet that collided with Jupiter in the early Solar System and then was caught in orbit by Jupiter's gravity.
E) More information is needed before any conclusion can be made.

Question 9

Based on the figure below, this moon

A) is geologically active.
B) is possibly geologically active.
C) was geologically active in the past but is no longer active.
D) is geologically dead.
E) More information is needed before any conclusion can be made.

Question 10

When a moon is cold enough that frozen water acts like a rock, and liquid water is found in "hot" flows or geysers, we call this type of activity

A) irregular hydrology.
B) Enceladus-like.
C) cryovolcanism.
D) the ice cycle.
E) hydrogeology.

Question 11

How many moons are known in the Solar System?

A) less than 50
B) at least 150
C) around 10
D) many thousands
E) several million

Question 12

Which of the following is a characteristic of irregular moons?

A) They revolve around their planets in the same direction as the planets rotate.
B) They are often large (up to as big as Earth's Moon).
C) They are usually tidally locked to their parent planets.
D) They have elliptical and inclined orbits.
E) They formed in an accretion disk around their parent planet.

Question 13

Which property of a moon might lead you to believe it was a captured asteroid?

A) It is tidally locked.
B) Its orbital axis is tilted by 5 degrees compared to the planet's rotational axis.
C) It orbits in the opposite direction than its planet rotates.
D) Its surface is very smooth and lacks craters.
E) It is roughly the size of Earth's moon.

Question 14

How do regular moons orbit in comparison to their planet's rotation?

A) in the same direction
B) in the opposite direction
C) sometimes in the same direction and sometimes in the opposite direction
D) Unlike their planets, moons don't rotate at all.
E) Moons are always tidally locked to their parent planet.

Question 15

Based on the figure below, this moon

A) is geologically active.
B) is possibly geologically active.
C) was geologically active in the past but is no longer active.
D) is geologically dead.
E) More information is needed before any conclusion can be made.

Question 16

Which of the following can be used as an indicator of the age of a moon's surface?

A) color of the surface
B) crater density
C) volcanic activity
D) radioactive dating
E) all of these

Question 17

The varied colors found on Io's surface are due to the presence of various molecules containing

A) sulfur.
B) silicon.
C) iron.
D) mercury.
E) magnesium.

Question 18

What does a darkened surface indicate on a rocky moon, as compared to a different moon with a lighter surface?

A) It indicates the presence of cooling lava from volcanic eruptions.
B) It indicates that the surface of the darkened moon is older than that of the lighter moon.
C) It indicates that the surface of the darkened moon is younger than that of the lighter moon.
D) It indicates an elevated level of organic compounds on the surface.
E) It indicates a colder region on the surface of the planet.

Question 19

Based on the figure below, this moon

A) is geologically active.
B) is possibly geologically active.
C) was geologically active in the past but is no longer active.
D) is geologically dead.
E) More information is needed before any conclusion can be made.

Question 20

Cryovolcanism occurs when

A) molten lava freezes when it reaches the surface because of extremely low temperatures.
B) volcanoes erupt underwater.
C) an icy moon has volcanoes emitting molten lava from deep underground.
D) low-temperature liquids explode through the surface because of increasing pressure underground.
E) a comet hits an object and causes volcanic eruptions.

Question 21

The density of particles in a planet's rings can be measured using

A) infrared light.
B) the Doppler shift.
C) shadows cast by nearby moons.
D) light from background stars.
E) their proper motions.

Question 22

Which of the following moons do scientists believe most closely represents the primordial Earth, although at a much lower temperature?

A) Titan
B) Europa
C) Callisto
D) Io
E) Ganymede

Question 23

Which of the following planets has the most complex and conspicuous ring system?

A) Mars
B) Jupiter
C) Saturn
D) Uranus
E) Neptune

Question 24

Titan is a high-priority candidate for the search for life outside Earth primarily because it has

A) liquid water on its surface.
B) an oxygen atmosphere like Earth's.
C) warm temperatures.
D) active lava volcanoes.
E) organic material.

Question 25

Which of the following moons is thought to have a vast ocean of water beneath its frozen surface?

A) Triton
B) Europa
C) Mimas
D) Io
E) Callisto

Question 26

What sort of liquids do astronomers expect to exist on Saturn's moon Titan?

A) lakes of liquid nitrogen, N₂
B) lakes of normal water, H₂O
C) lakes of ammonia and hydrogen sulfide
D) lakes of methane, ethane, and other hydrocarbons
E) lakes of liquid iron

Question 27

Two years after first being observed, astronomers reported that Saturn's rings vanished. What happened to them?

A) The old ring system dissipated, and since then a new one has formed.
B) The orbital plane of the rings was seen edge-on, and the rings were too thin to be visible.
C) Most telescopes used hundreds of years ago couldn't adequately resolve the ring system.
D) Astronomers were looking at the wrong planet, leading to the chance discovery of Uranus.
E) They were hidden behind some of Saturn's many moons.

Question 28

Which of the following moons shows no signs of geological activity at any point in its history?

A) Callisto
B) Triton
C) Europa
D) Enceladus
E) Io

Question 29

In the figure below showing Titan's surface, reflections off of dark surface features are strong evidence that these features are

A) dried lava flows.
B) recent impact craters.
C) large sheets of frozen water ice.
D) composed of liquids.
E) a rocky material different from that of the lighter-colored surface.

Question 30

What leads astronomers to believe that some large moons associated with the giant planets have compositions that are roughly half water?

A) Spectroscopic analysis indicates the presence of large bodies of water.
B) They have average densities midway between water and rock.
C) Space probes have drilled into the surfaces of many of the moons and detected water.
D) Rocks and other features that form only in the presence of water have been observed.
E) Astronomers have observed the gravitational effects of tides on those moons.

Question 31

How do astronomers take such detailed, close-up pictures of ring systems?

A) They send satellites to the outer planets to take pictures for us.
B) They take them using backyard telescopes, just like Galileo did.
C) They take them using the largest optical telescopes on Earth.
D) They have astronauts in space take pictures of them.
E) They wait until the planet is closest to Earth and use the Hubble Space Telescope.

Question 32

Which of the following moons is geologically dead?

A) Callisto
B) Io
C) Europa
D) Enceladus
E) Titan

Question 33

Titan's thick atmosphere is believed to have been created when ultraviolet photons broke apart methane molecules, ultimately creating the observed smoglike conditions.However, this process would likely remove all of the atmospheric methane in roughly 10 million years, and yet we still see methane's presence today.What is the most likely cause for this?

A) Cometary impacts periodically bring new methane to Titan.
B) Ethane rains down out of the atmosphere, combines with surface rocks, and creates new methane.
C) Infrared photons give atmospheric molecules enough energy to recombine into methane.
D) Volcanoes on Titan periodically release new methane into the atmosphere.
E) Bacteria on Titan constantly replenish the methane in the atmosphere.

Question 34

How does the geological activity on Io compare to the activity on other moons?

A) It is almost completely inactive.
B) It occurs at widely spaced intervals but is highly active when it does occur.
C) It is very active on a regular basis.
D) It used to be inactive but has slowly increased activity over the past few million years.
E) None of these is an accurate description of Io's geological activity.

Question 35

Which giant planets have rings?

A) all of them
B) only Jupiter and Saturn
C) only Saturn
D) only Saturn and Uranus
E) none of them

Question 36

Saturn's rings disappear from sight every

A) 40 years.
B) 25 years.
C) 15 years.
D) 8 years.
E) 6 months.

Question 37

Io has the most volcanic activity in the Solar System because

A) it is continually being bombarded with material in Saturn's E ring.
B) it is one of the largest moons and its interior is heated by radioactive decays.
C) of gravitational friction caused by the moon Enceladus.
D) its interior is tidally heated as it orbits around Jupiter.
E) the ice on the surface creates large pressure on the water below.

Question 38

Which terrestrial planet has rings?

A) Mercury
B) Venus
C) Earth
D) Mars
E) None of the terrestrial planets have rings.

Question 39

Which object has been turned inside out numerous times, leading to a situation where lighter elements have escaped, sulfur compounds compose the crust, and primarily heavier elements
Make up its core?

A) Mercury
B) Titan
C) Callisto
D) Pluto
E) Io

Question 40

From where does Titan's thick, nitrogen-rich atmosphere likely arise?

A) photodissociation of methane and ammonia in its atmosphere
B) It is emitted by frequent volcanic eruptions.
C) It has been deposited by ongoing cometary impacts over the age of the Solar System.
D) photosynthesis of algae in oceans that lie beneath its icy surface
E) It was released from underground reservoirs by early impacts.

Question 41

How do particles from the moon Enceladus wind up in Saturn's E ring?

A) Volcanoes erupt and expel silicates into space.
B) Water geysers erupt from the surface and expel them into space.
C) Cosmic rays bombard the surface rock on Enceladus and expel it into space.
D) A collision with a co-orbiting moon knocks rocky debris into orbit around Saturn.
E) Strong winds from Saturn blow material off of Enceladus's surface.

Question 42

Which of the following materials can be found within planetary rings in our Solar System?

A) water ice
B) silicates
C) organic materials
D) boulder-sized rocks
E) all of these

Question 43

Saturn's G ring, as shown in the figure below, is known as

A) a ringlet.
B) an arclet.
C) a diffuse ring.
D) a spoke.
E) a crepe ring.

Question 44

Astronomers originally planned to have the Pioneer 11 space probe pass through the Cassini Gap in Saturn's rings.Would this have been completely safe?

A) Yes, but they decided that it was more important to observe Saturn's moons.
B) Yes, but they decided to land on the rings instead.
C) No, because the Cassini Gap is too narrow.
D) No, because the Cassini Gap is not completely empty.
E) No, because the same gravitational influences that create the Cassini Gap would have destroyed the probe.

Question 45

The mass of all of Saturn's bright rings is comparable to the mass of

A) a small comet.
B) a small icy moon.
C) Earth's Moon.
D) Mars.
E) Venus.

Question 46

How does the thickness of Saturn's bright ring system compare to its diameter?

A) It's about 10 times thinner.
B) It's about 1,000 times thinner.
C) It's about 10,000 times thinner.
D) It's about 100,000 times thinner.
E) It's about 10 million times thinner.

Question 47

The "kinks" in Saturn's F Ring, shown in the figure below, are caused by

A) Saturn's magnetic field.
B) the gravitational influence of the two pictured moons.
C) regions of dark dust and rocks in the ice ring.
D) comets or asteroids that had plunged through the rings in the past.
E) proximity to Saturn's Roche limit.

Question 48

Braided rings, scalloped edges, gaps, knots, and kinks can all be caused by

A) moons with highly inclined orbits.
B) shepherd moons.
C) gravitation interactions between the ring materials themselves.
D) sunlight reflecting off different materials.
E) strong magnetic fields.

Question 49

If a planetary ring had an inner diameter of 100,000 km, an outer diameter of 120,000 km, a thickness of 10 m, and a density of 100 kg/m³, what would be the total mass of material in this ring?

A) 6 *10²⁰ kg
B) 5* 10²³ kg
C) 4 *10¹⁵ kg
D) 2 * 10²¹ kg
E) 3 * 10¹⁸ kg.

Question 50

What observational setup is required to observe backlit rings?

A) The light source doing the backlighting has to have wavelengths much longer than the size of the ring particles.
B) The light source doing the backlighting has to have wavelengths comparable to the size of the ring particles.
C) The light source doing the backlighting has to have wavelengths much shorter than the size of the ring particles.
D) The light source doing the backlighting must be a blackbody source peaking in the visible part of the spectrum.
E) The light source doing the backlighting must be very distant

Question 51

What influence do pairs of shepherd moons have on the giant planets' rings?

A) They gravitationally pull material off each other, reinforcing the rings.
B) They only allow the rocky ring systems to remain stable while destabilizing the icy ring systems.
C) They cause the rings to eventually fall into Saturn by gravitational tugs on the ring particles.
D) They keep rings between the pair narrow by gravitational tugs on the ring particles.
E) They prevent rings from forming between their respective orbits.

Question 52

Ring particles range in size from tiny grains to

A) house-sized boulders.
B) basketball-sized boulders.
C) city-sized chunks.
D) tennis ball-sized rocks.
E) fingernail-sized pebbles.

Question 53

If you wanted to search for faint rings around a giant planet by sending a spacecraft on a flyby, it would be best to make your observations

A) as the spacecraft approached the planet.
B) after the spacecraft passed the planet.
C) while orbiting the planet.
D) during the closest flyby.
E) while orbiting one of its moons.

Question 54

Which of the following is a possible way to renew particles in a ring system?

A) volcanic eruptions on the parent gas giant
B) a collision between moons or other objects near the ring system
C) comet tails getting trapped in the planet's orbit
D) a planet's gravity drawing particles from the nearby interstellar medium
E) none of these

Question 55

If the Moon had active volcanoes,

A) the Moon would have a thick hydrogen atmosphere.
B) Earth might have a ring.
C) the Moon's surface would have more craters than it currently does.
D) life could not exist on Earth.
E) the Moon would have different phases than we see today.

Question 56

Ring material

A) is made primarily of fine dust.
B) has always orbited the giant planets.
C) reflects more than 75 percent of the light that falls on it.
D) must constantly be renewed or the rings fade.
E) is made primarily of kilometer-sized rocks.

Question 57

Of what are Saturn's brightest, thickest rings primarily made?

A) a thin, solid surface of rock and ice
B) an orbiting cloud of high-density gas
C) hundreds to thousands of smaller ringlets
D) a very diffuse collection of dust
E) asteroid-sized rocks

Question 58

What is the escape velocity from Europa, whose radius is 1,600 km and mass is 5 * 10²² kg?

A) 27 km/s
B) 7.0 km/s
C) 2.0 km/s
D) 15 km/s
E) 0.3 km/s

Question 59

Which moon gives rise to the particles that make up Saturn's E ring?

A) Titan
B) Triton
C) Callisto
D) Enceladus
E) Thethys

Question 60

Of what are Saturn's rings primarily made?

A) water ice
B) methane
C) nitrogen
D) dark organic material
E) dark silicate material

Question 61

What's the most likely way a dwarf planet such as Pluto was able to acquire four moons comparable in size to itself?

Question 62

How do Uranus's rings differ from the ring systems of the other giant planets?

A) Uranus has only one ring made up of fine dust.
B) Uranus has the most spectacular ring system with many bright, wide rings.
C) Uranus has 13 rings that are narrow and widely spaced.
D) Uranus has rings that are clumped into several arclike segments.
E) Uranus has rings that are solid enough to land on.

Question 63

What is the most likely reason that a planet's rings would reflect more than 50 percent of the sunlight they receive?

A) They are made of ice.
B) They are made of silicate rock.
C) They are made of liquid.
D) They are made of iron.
E) They are very old.

Question 64

What are three characteristics of the orbits of irregular moons, and how do planets gain irregular moons?

Question 65

Rings that look like they are intertwined (but are not) are caused by

A) new laws of physics.
B) ring material on highly elliptical orbits.
C) the gravitational influence of small moons.
D) electromagnetic interaction of the rings with Saturn's magnetic field.
E) meteoroid impacts.

Question 66

Rings of giant planets are very thin compared to their diameters mainly because

A) of collisions between ring particles.
B) moons that tidally disrupt have small diameters.
C) energy is conserved when a moon tidally disrupts.
D) the planets have large tidal forces.
E) shepherd moons force them to be extremely thin.

Question 67

Why are some of Saturn's rings diffuse?

A) Particles in diffuse rings collide infrequently, allowing them to maintain irregular orbits and spread out.
B) Particles in diffuse rings are composed of transparent materials.
C) Diffuse rings are made of methane, instead of water ice
D) Diffuse rings are composed of charged particles, which are spread out by magnetic forces.
E) Sunlight heats diffuse rings, causing the material to spread out.

Question 68

What can we conclude from a random distribution of volcanoes on a moon, and why?

Question 69

What makes extremophile organisms different from other life forms?

A) They can live in extreme conditions, such as very low- or high-temperature environments, oxygen-poor environments, or environments with extremely low light levels.
B) They live only in environments with extremely high levels of sunlight.
C) They live in environments lacking in organic compounds.
D) They live in environments where little to no water is found, such as deserts.
E) They can live in any environment, even deep vacuum.

Question 70

Saturn's rings are much brighter than the rings of the other giant planets because

A) Saturn is closer to the Sun and receives a higher flux of sunlight.
B) the material in Saturn's rings is made mostly of ice rather than rock.
C) Saturn's rings have over 100 times the density of other ring systems.
D) Saturn's rings are tilted by a larger angle relative to our line of sight.
E) the material in Saturn's rings is much hotter than material in other ring systems.

Question 71

The semimajor axis of Iapetus's orbit around Saturn is approximately 3.56 * 10⁶ km, and its orbital period is approximately 79 days.Use these data and Newton's version of Kepler's third law to calculate the mass of Saturn.

Question 72

Particles that make up the rings of Uranus and Neptune are composed of

A) rocky material from tidally disrupted moons.
B) organic material that has darkened because of bombardment by high-energy
Charged particles.
C) icy material from tidally disrupted comets.
D) magma from volcanic eruptions on the surfaces of their moons.
E) all of these

Question 73

Explain how a planet obtains a regular moon orbiting it.

Question 74

What material has been seen erupting from the surface of the icy moon Enceladus, and why?

Question 75

Ganymede is one of the largest moons in the Solar System.It shows some terrain that is ancient and heavily cratered, and some younger terrain with fewer craters, but no terrain that is free of craters.Why would Ganymede's geological activity stop?

Question 76

Saturn's E Ring is generated by material ejected from its moon Enceladus (the bright dot within the ring), as pictured in the figure below.What is the minimum velocity that
Enceladus's material must achieve in order to become part of the ring? Enceladus has a mass
Of 1.08 *10²⁰ kg and a radius of 250 km.

A) 3.2 km/s
B) 1.7 km/s
C) 1.1 km/s
D) 0.55 km/s
E) 0.24 km/s

Question 77

What are the orbital characteristics of a regular moon?

Question 78

Name two properties of moons that are in tidally locked orbits.

Question 79

What are the two basic materials from which the moons in the Solar System are composed?
For each type of material, name an example of a moon whose surface is composed primarily
of that material.

Question 80

Jupiter's rings are made of material from

A) its innermost moons.
B) its upper atmosphere.
C) its outermost moons.
D) only Io.
E) only its retrograde moons.