AST Exam 3

What, if anything, do you think we should be doing to alleviate the threat of global warming?

- improve energy efficiency - replace fossil fuels with alternative energy sources - reduce the emissions of greenhouse gases

Earth's temperature remains fairly steady, which means that Earth must return nearly the same amount of energy to space that it receives from the Sun. In what forms does Earth return most of this energy to space?

- infrared light emitted by the surface and atmosphere - visible light reflected by the surface - visible light reflected by clouds

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.

Based solely on an understanding of the greenhouse effect (as displayed in the figure), which one of the following statements is true?

We should expect an increase in the greenhouse gas concentration to lead to global warming.

The bright spherical part of a comet observed when it is close to the Sun is the

coma

Australia is composed of relatively old and thick

continental crust

About how often does a 1-kilometer object strike the Earth?

every million years

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

In the case of the Oort cloud, close gravitational encounters between icy planetesimals and the ___________ caused the comets to move outwards to huge distances where they formed the Oort cloud. Nudges from other stars affected their orbits enough that most comets never reenter in the inner solar system.

jovian planets

The oxygen in Earth's atmosphere was released by

life.

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

Particles ejected from a comet can cause a(n) _______ on Earth.

meteor shower

A comet's ________ is the frozen portion of a comet.

nucleus

A comet's plasma tail always points directly away from the Sun because __________.

of pressure exerted by the fast-moving charged particles in the solar wind

A comet's ________ stretches directly away from the Sun.

plasma tail

In the case of the asteroid belt the jovian influence ________ the formation of a terrestrial planet. In both of the asteroid belt and the Kuiper belt cases, resonances further nudge the objects onto very elliptical orbits, which can result in _____________

prevented collisions with the other planets

Which heat source continues to contribute to Earth's internal heat?

radioactive decay

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

Dione

Strong evidence both from surface features and magnetic field data support the existence of a subsurface ocean on

Europa

. The largest moon in the solar system is

Ganymede

Why does Neptune appear blue and Jupiter red?

Methane in Neptune's atmosphere absorbs red light.

In another star system, astronomers discover an object the size of Earth orbiting its star at the distance of the Kuiper belt.

Surprising. Terrestrial planets are not expected to form in regions where ice is common.

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

The jovian planets have profoundly affected the orbits of small bodies. Through the action of orbital resonances, Jupiter affects the _______ belt and Neptune affects the ________ belt.

asteroid Kuiper

A comet entering the inner solar system from afar will __________.

form a coma and some time later form a tail

You have found that Planet Z should have active tectonics and volcanism and an atmosphere produced by volcanic outgassing. What single factor explains why the planet should have these characteristics?

has a large size for a terrestrial planet.

Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a

hot spot

The main ingredients of most satellites of the jovian planets are

hydrogen compound ices.

When you zoom in on the section labeled "Southern Highlands," which geologic processes are most clearly evident?

impact cratering and erosion

Some jovian planets give off more energy than they receive because of

ongoing contraction or differentiation.

The fact that Europa orbits Jupiter twice for every one orbit of Ganymede is an example of a(n)

orbital resonance

Jupiter nudges the asteroids through the influence of

orbital resonances.

Saturn's many moons affect its rings through

orbital resonances.

The extremely deep ocean Marianas Trench is a result of

subduction

During the time that a comet passes through the inner solar system, the comet can appear quite bright because __________.

sunlight reflects off the comet's tail and coma

How many of the five terrestrial worlds are considered "geologically dead"?

two

The average temperature over the past 1000 years has been about 15∘C. From the graphs, you can conclude that Earth's average temperature during the past 800,000 years has __________.

varied between about 7∘C and 19∘C

The energy that warms Earth's surface comes primarily in the form of __________.

visible light from the Sun

Which of the following is a strong greenhouse gas?

water vapor

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

Can an asteroid be pure metal?

Yes, it must have been the core of a shattered asteroid.

________is the most distant of Jupiter's four Galilean moons.

Callisto

The jovian moon with the most geologically active surface is

Io

Why is Io more volcanically active than our moon?

Io has a different internal heat source.

As you learned 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 periodically passes Europa and Ganymede in the same orbital position.

Io experiences tidal heating primarily because __________.

Io's elliptical orbit causes the tidal force on Io to vary as it orbits Jupiter.

What is unusual about Triton?

It orbits its planet backward.

Which describes our understanding of flowing water on Mars?

It was important once, but no longer.

What would happen if a 1-kilometer object struck the Earth?

It would cause widespread devastation and climate change.

Why is Jupiter denser than Saturn?

Its higher mass and gravity compress its interior.

Which are thought to have formed farthest from the Sun?

Kuiper belt comets

Did a large terrestrial planet ever form in the region of the asteroid belt?

No, because Jupiter prevented one from accreting.

Which of the following Mars surface features provides dramatic evidence that volcanism has played a role in shaping the surface of Mars?

Olympus Mons

About a trillion comets are thought to be located far, far beyond Pluto in the

Oort cloud

According to scientists, the naturally occurring greenhouse effect makes Earth about 31∘C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases?

They calculate this temperature from Earth's reflectivity and distance from the Sun.

________ is responsible for the tremendous volcanic activity on Io.

Tidal heating

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

Titan

Which terrestrial world has the most atmospheric gas?

Venus

All of the following statements are true. Which one provides strong observational support for the claim that greenhouse gases make a planet warmer than it would be otherwise?

Venus has a higher average temperature than Mercury.

What does Pluto most resemble?

a comet

In Part A, you found that Planet Z should not have strong winds and violent storms. What single change to Planet Z's characteristics would cause it to have strong winds and violent storms?

a faster rotation rate

The earthquakes that occur in Southern California generally occur above a

fault

The slowly increasing distance between South America and Africa is due to

seafloor spreading

Layered _________ exposed by erosion can be seen when looking at the Grand Canyon in the United States.

sedimentary rock

Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?

size

Which lists the jovian planets in order of increasing distance from the Sun?

Jupiter, Saturn, Uranus, Neptune

The ________ extends from about beyond the orbit of Neptune to about twice the distance of Neptune from the Sun.

Kuiper belt

The asteroid belt lies between the orbits of

Mars and Jupiter.

Which have the most elliptical and tilted orbits?

Oort cloud comets

What do we conclude if a planet has few impact craters of any size?

Other geological processes have wiped out craters.

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.

are continually supplied by impacts with small moons.

Saturn's rings

______ found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.

Seafloor crust

Assuming that features you see on Mars are similar to features found on Earth, what would a casual inspection of the interactive photo of Mars lead you to suspect about water on Mars?

Surface water only exists as frozen ice.

How big an object causes a typical shooting star?

a grain of sand or a small pebble

In Part A, you found that Planet Z should not have polar ice caps or liquid water. What single change to Planet Z's characteristics would allow it to have these things?

a greater distance from its star

In Part A, you found that Planet Z should not have seasons. What single change to Planet Z's characteristics would cause it to have seasons?

a larger axis tilt

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________.

absorb infrared light emitted by the surface

Where is the most CO2 that has outgassed from Earth's volcanoes?

locked up in rocks