w8 chp 13

The fact that Jupiter's moons rotate on their axes in synchronism with their respective orbital motion, taking the same time to rotate as they do to revolve about the planet, was discovered long before detailed images of the moons were available from spacecraft. How was this fact first discovered?

Brighter and darker surface features cause variations in brightness that were observed to repeat every orbital period of the moon.

Cassini is the latest in the long line of robotic probes sent out to explore. What did it discover that was not known before?

Cassini discovered rivers of hydrocarbons on Titan.

The ____________ mission dropped a probe onto ____________ .

Cassini; Titan

Which of Saturn's icy satellites shows one side with an old, heavily cratered surface and the other side with a much younger, tectonically modified surface?

Dione

____, one of Saturn's icy moons, is unusual in the solar system because it has volcanic activity that ejects plumes of icy particles into space.

Enceladus

The brightest four moons of Jupiter were used first by ____ to show that objects orbited about other objects the solar system.

Galileo

Which mission only went to Jupiter and not to Saturn?

Galileo

Io, Europa, and Ganymede have orbital periods in the ratio 1:2:4. At some time all three moons are lined up on the same side of Jupiter. After Europa goes once around Jupiter, observers on Europa would not be able to see ____.

Ganymede

The Galilean moon which shows evidence of tectonic activity is

Ganymede

The most massive moon in the solar system is _____.

Ganymede

The largest satellite (moon) in our planetary system is

Ganymede, a moon of Jupiter.

_______, the probe that soft-landed on the surface of Saturn's moon Titan found evidence suggesting fresh methane rainfall.

Huygens

Which of the following is a reason to send humans to explore the outer Solar System?

If something unexpected happens, humans can 'think outside the box'.

We now believe there is water ice on or under the surface of each of the Galilean moons of Jupiter except

Io

Because of Jupiter's strong gravitational pull, Io is locked in a synchronous orbit around the planet. How does Io respond to this pull?

Io's long axis remains pointed (more or less) toward Jupiter while the surface revolves at a constant rate. This results in a slight movement between the two and causes tidal friction and heat.

What characteristic of Saturn's satellite Titan makes it different from any other known satellite in the solar system?

It has a permanent, dense atmosphere.

What feature of the Saturnian moon Enceladus makes it a unique object in our solar system?

It has the most reflective surface of all objects in the solar system.

Callisto apparently has a planetwide magnetic field. What characteristics do we tentatively assign to this field?

It is at least in part induced from Jupiter's magnetic field and sustained in liquid subsurface oceans of water mixed with minerals.

Titan is a remarkably different moon. Which one of the following statements is not true about Titan?

It is kept at a high temperature, possibly by volcanoes and tidal effects.

What characteristic of Jupiter's moon Io makes it different from any other known satellite in the solar system?

It is volcanically active.

At the end of the mission of Galileo in 2003, the spacecraft was sent to burn up in the atmosphere of Jupiter. Why was it not just left floating in space?

It was feared Galileo might someday crash on Europa and contaminate its oceans with biological organisms from Earth.

When Galileo first discovered the large moons of Jupiter in 1610 he called them the ______ stars.

Medicean

Four of the moons of Saturn are

Mimas, Enceladus, Titan, and Dione.

A magnetic field has been detected associated with Jupiter's satellite Io, which is smaller than our Moon. How can such a small object produce a significant magnetic field?

Most small objects cool rapidly, solidify, and produce no magnetic field. Io, however, has been unable to solidify because of the tidal flexing from Jupiter's gravitational field.

How were the hydrocarbon lakes of Titan discovered?

Radar maps made by Cassini to measure the height of the terrain revealed many flat areas

There are a number of advantages to robotic mission. Which of the following is NOT an advantage?

Robots are more flexible and creative about solving unexpected problems.

In terms of the relationship between the periods P and semimajor axes a of their orbits around Jupiter, how do the moons of Jupiter behave?

The moons do follow the Keplerian relationship P2 = ka3, where k is a constant (the same for each moon) that is different from the constant governing planetary motion around the Sun.

The image you saw of Ganymede taken by Galileo shows cracks in Ganymede's surface. Scientists interpret these cracks as one piece of evidence that the moon might have liquid water beneath its surface; the water would be pushing up the surface here and forcing it apart. Why did scientists working on Voyager NOT reach the same conclusion?

The scientists saw something in the Voyager images, but the images were so unclear that they couldn't tell that they were cracks.

The Galilean moons of Jupiter are bright enough to be seen with the unaided eye. Yet no one reported seeing them before Galileo observed them through a telescope. Why were they not recorded earlier?

The unaided eye cannot resolve the images of the moons separately from the bright glare of Jupiter.

What specific features led astronomers to conclude that Europa had undergone geological transformation in relatively recent times?

There are very few craters upon its surface.

Ganymede and Callisto, two of the Galilean satellites of Jupiter, have mean densities of about 1900 kg/m3. What does this tell us about the probable composition of these two satellites?

They are a mixture of roughly equal quantities of rock and ice.

Why had Io's volcanoes and Jupiter's rings never been discovered with Earth-based telescopes?

They are too small and faint to be seen from Earth.

If intelligent life elsewhere in the universe ever finds the Voyager Golden Record and figures out how to play it, what will they learn about Earth?

They will see and hear a snapshot of what life on Earth was like in the late 1970s

Radioactive decay was the source of the internal energy that allowed volcanoes on ____ to outgas the methane found abundantly in its atmosphere.

Titan

What was the primary reason why scientists in the early 1970s wanted to send robotic missions to Jupiter, Saturn, and their moons?

To take images and measurements not possible from Earth.

The surface of Europa, one of Jupiter's Galilean satellites, is characterized by

a fractured crust of ice with evidence of ice rafts and areas of flooding at some earlier time.

Europa, one of the Galilean satellites of Jupiter, has a surface consisting of

a relatively young, icy crust covered with a network of streaks and cracks, and only a few impact craters.

The structure of Callisto, the outer Galilean satellite of Jupiter, is thought to be

a thick ice crust and a slushy mantle of ice and water over a core of rock.

How many of the large Galilean satellites are in synchronous rotation around Jupiter (always turning the same face toward Jupiter)?

all 4

The orbits of the Galilean moons of Jupiter

all lie in the plane of Jupiter's equator.

Io, Europa, and Ganymede have orbital periods in the ratio 1:2:4. At some time all three moons are lined up on the same side of Jupiter as seen from Earth. After Europa goes once around Jupiter,

all three moons are again lined up, but Io is on the opposite side of Jupiter from the other two. OR observers on Europa would not be able to see Ganymede.

At the present time, Titan has a dense atmosphere with opaque clouds that prevent us from seeing Titan's surface. What is believed to be the history of this atmosphere over the lifetime of Titan?

always dense but sometimes opaque and sometimes transparent

The dominant source of Ganymede's magnetic field is believed to be

an electric dynamo in Ganymede's interior.

What is believed to be the interior structure of Io, the innermost Galilean satellite of Jupiter (in order from the center to the surface)?

an iron core, partially molten rocky mantle, and solid crust

Which mission did NOT explore the moons of Saturn and Jupiter?

apollo

Most of the satellites of Jupiter beyond the innermost eight appear to be

asteroids captured by Jupiter.

In 2014 how many satellites for Jupiter are known?

between 60 and 70

There are few _____ on the surface of Europa, leading astronomers to conclude that Europa had undergone geological transformation in relatively recent times.

craters

The surface of Ganymede, a Galilean satellite of Jupiter, is characterized by

dark areas of ancient terrain and bright, younger, but still very old areas with many folded ridges indicating tectonic activity on Ganymede in the distant past.

____, one of Saturn's icy satellites, shows one side with an old, heavily cratered surface and the other side with a much younger, tectonically modified surface.

dione

Suppose you were to go back in time to the era when Jupiter's large satellites were forming. If you move outward from Jupiter, the first solid material you would encounter would be

dust-sized grains of iron and rocky materials.

The source of Callisto's magnetic field, discovered by the Galileo orbiter, is believed to be

electric currents induced by Jupiter's magnetosphere in a conducting layer of liquid water below Callisto's surface.

What does the surface of Europa, a moon of Jupiter, look like?

entirely ice, with fractures and ridges going in every direction and no features more than about 100 m high.

The surface of ____, one of Jupiter's Galilean satellites, is characterized by a fractured crust of ice with evidence of ice rafts and areas of flooding at some earlier time.

europa

The Huygens probe that soft-landed on the surface of Saturn's moon Titan found

evidence suggesting fresh methane rainfall.

The ice rafts on Europa

float on a surface of soft ice or water.

Of the spacecraft that have visited Jupiter, which was placed in orbit around the planet?

galileo

Suppose a moon is orbiting a large planet in a close but highly elliptical orbit. Which one of the following characteristics might you expect to find for this moon?

geologic activity

The source of heat that drives the volcanic eruptions of sulfur and sulfur compounds on Io, the giant moon of Jupiter, is tidal distortion and flexing caused by _____ effects from Jupiter and other moons.

gravitational

One very interesting fact about the lava that is seen to be flowing on Io is that its temperature is significantly _____ than that of lava on Earth, indicative of a different chemical composition.

higher

What would be a typical weather forecast on Titan, Saturn's largest moon?

hydrocarbon fog and methane rain in a nitrogen atmosphere

Callisto has a surface of _____ pocked with many old craters.

ice

Ganymede and Callisto, two of the Galilean satellites of Jupiter, have mean densities of about 1900 kg/m3. This tells us they are probably composed of a mixture of roughly equal quantities of rock and _____.

ice

Humans have explored the Jupiter or Saturn systems:

in great detail with robotic missions

Which one of the following changes would decrease volcanic activity on Io?

increase the distance from Jupiter to Io

A magnetic field has been detected associated with Jupiter's satellite Io. This field is a(n) _____ magnetic field

induced

Observations indicate that a large electric current flows through Europa, induced by Jupiter's magnetosphere sweeping over the planet. This requires an electrically conducting medium under the surface. In the case of Europa, this medium is believed to be

ionized water

Suppose you were to go back in time to the era when Jupiter's large satellites were forming. If you move outward from Jupiter, the first solid material you would encounter would be dust-sized grains of _____ and rocky materials.

iron

Titan, the large moon of Saturn, is able to maintain an atmosphere because

it has a relatively large mass and surface gravity, and its atmospheric temperature is low.

Titan, the large moon of Saturn, is able to maintain an atmosphere because it has a relatively large mass and surface gravity, and its atmospheric temperature is ____.

low

The interior structure of Io is believed to be an iron core, partially molten rocky ____, and solid crust

mantle

The most abundant component of the atmosphere of Titan, the largest moon of Saturn, is ____.

nitrogen

Earth-based observations of the motions of Jupiter's large moons have resulted in measurements of the mass(es) of

only Jupiter itself.

When compared to other objects in the solar system, the Galilean satellites of Jupiter are about the size of

our Moon or a bit larger.

Volcanoes on the surface of Io are distributed

over the whole surface

What is believed to be the source of the internal energy that allowed volcanoes on Titan to outgas the methane found abundantly in its atmosphere?

radioactive decay

The surface of Callisto, the outer Galilean moon of Jupiter, can best be described as

relatively smooth, with a great many impact craters and one large basin created by an asteroid impact.

Images taken by Galileo of the surface of Ganymede:

revealed cracks that were not clearly seen in the images taken by Voyager.

The brightest four moons of Jupiter were used by Galileo to

show that objects orbited about other objects the solar system.

One very interesting fact about the lava that is seen to be flowing on Io is that its temperature is

significantly higher than that of lava on Earth, indicative of a different chemical composition.

Which of the following features is not a characteristic of Jupiter's moon Io?

smooth plains of ice crisscrossed by networks of cracks

The first missions to the Jupiter and Saturn systems involved sending:

spacecraft to fly-by those planets

Io has a surface of

sulfurous volcanoes and geysers.

The most abundant component of the atmosphere of Titan, the largest moon of Saturn, is nitrogen. The nitrogen was first observed by

the Voyager 1 fly-by mission in 1980.

What is perhaps the most remarkable finding to come from the exploration of Jupiter's moon Europa by the Galileo spacecraft?

the existence of a liquid water ocean under the ice crust

Why did scientists decide to send Galileo falling into Jupiter at the end of its mission? To prevent:

the probe from contaminating possible life on Jupiter's moons with bacteria from Earth.

Suppose you have calculated the speed of Ganymede in its orbit from Kepler's laws. And you time the interval between when Ganymede first begins to disappear into Jupiter's shadow and when it is totally occulted by Jupiter. What can you calculate from this information?

the radius of Ganymede

The source of heat that drives the volcanic eruptions of sulfur and sulfur compounds on Io is

tidal distortion and flexing caused by gravitational effects from Jupiter and other moons.

The surface of Europa shows evidence of geologic activity. What is believed to be the source of the energy for this activity?

tidal forces from Jupiter

The internal temperature of Io is high because of

tidal heating from Jupiter's gravity.

Extensive volcanic activity observed on Jupiter's satellite Io is caused by

tidal stresses from Jupiter and the other Galilean moons.

When a spacecraft flies by a body such as a planet or a moon, we can carefully monitor its trajectory. This information can tell us the body's

total mass and shape but not its magnetic field.

On the basis of the relationship between the orbital periods of Io and Europa, these two moons would come close together in their orbital paths once every ____?

two Io orbits.

Enceladus, one of Saturn's icy moons, is unusual in the solar system because it has

volcanic activity that ejects plumes of icy particles into space.

What mission went beyond Saturn and explored Uranus and Neptune?

voyager 2

The chemical composition of the Galilean satellites tells us that the Jovian nebula

was warmer in the center than in the outer regions.

Callisto apparently has a planetwide magnetic field. Astronomers believe it is in part induced from Jupiter's magnetic field and sustained in liquid subsurface oceans of ____ mixed with minerals.

water

Perhaps the most remarkable finding to come from the exploration of Jupiter's moons by the Galileo spacecraft was the existence of _____ under the surfaces.

water