Chapter 16 Astronomy
Which location experiences earthquakes caused by shifts along a tectonic plate?
California
Which is not considered a terrestrial planet?
All of these are considered terrestrial planets.
What adverse affect is human activity having on today's atmosphere?
All of these choices are correct.
What makes Earth peculiar among the terrestrial planets?
All of these choices are correct.
Which of the following is due to the moon's small size?
All of these choices are correct.
What must be true about Earth's core to generate Earth's magnetic field?
All of these choices must be true.
How does the large-impact hypothesis explain the moon's lack of iron?
Both planetesimals were differentiated, and the two iron cores went to Earth.
What are the characteristics of a rock that is a breccia?
Breccia is rock consisting of broken rock fragments that are cemented together by heat and pressure.
The moon's craters Copernicus and Tycho both have circular rims with a central peak. Tycho has a comparatively sharp, well defined rim while Copernicus has smaller craters that make its rim less well defined. During a given time many more small meteorites strike all over the moon compared to the ones that created the Copernicus and Tycho craters. What is the relative age of the crater Copernicus to the crater Tycho and how can you tell?
Copernicus is older because many more meteorites have struck its rim.
A Sense of Proportion: Arrange the following stages in the development of a terrestrial planet in order from first to last
Differentiation , cratering , flooding , slow surface evolution
Which planet's atmosphere has evolved the most due to living things?
Earth
How do we know Earth differentiated?
Earth has a dense core and a low-density crust.
What about the above figure makes Earth unique among terrestrial planets?
Earth is the only terrestrial planet with oceans.
With respect to the early history of Earth, select all of the correct statements from the following list.
Earth's large amounts of liquid water is unique among terrestrial planets. Surface evolution is a slow process. Earth started out molten. Earth is the only planet known to be a home for life.
With respect to the solid Earth, select all of the correct statements from the following list.
Earth's magnetic field is produced by its metal core. Earth has a solid iron and nickel central core. Much of Earth's geologic past is erased by erosion. Plate tectonics is driven by heat from Earth's interior. Volcanoes and earthquakes are most likely along tectonic boundaries.
Why is the figure a typical view of the surface of Earth?
Earth's surface is mostly covered by water.
Which location experiences earthquakes caused by volcanism?
Hawaii
Why do almost all impact craters have a circular shape?
High-speed projectiles vaporize explosively upon impact, sending out spherical compression waves.
How do we know that Copernicus is a young impact crater?
It has bright rays that extend onto the surrounding maria.
Which of the following is true about Earth's ozone layer?
It is located at an altitude of about 25 km and a hole develops every October over Antarctica.
Which of the following is true for Earth's core?
It is solid on the inside, and liquid on the outside.
What must be true for a large portion of Earth's core in order for convection to occur?
It must be liquid.
Has tectonics occurred on the moon?
It never occurred.
Why was the lunar terrain shown in the above figure chosen for the early Apollo missions?
It was easier to land on.
What is the likely source of Earth's early atmosphere that consisted of carbon dioxide and water vapor?
It was outgassed from Earth's interior during volcanic activity and it arrived in the form of icy planetesimals that impacted Earth.
Why did the first Apollo missions land on the maria?
It was thought to be safer due to the smoother terrain and thinner regolith.
How does the above figure suggest that heat is flowing out of Earth's interior?
Material is coming from beneath the surface of Earth and geologic activity would not occur without internal heat from a planet.
What happened to the majority of the carbon dioxide that was formerly in Earth's atmosphere?
Most of it dissolved into the oceans and now is in the form of limestone rocks of Earth's crust.
How does the large-impact hypothesis explain the moon's lack of volatile elements?
Most of the volatile elements would have vaporized in the collision and/or been lost into space.
How was the Hawaiian-Emperor island chain formed?
Motion of the Pacific plate allowed volcanic hot-spots to punch through the crust.
How do P waves and S waves differ?
P waves oscillate parallel to their direction of travel, whereas S waves oscillate perpendicular to their direction of travel and P waves can pass through liquids, whereas S waves cannot.
What evidence do we have that Earth's outer core is a metallic liquid?
S waves are blocked, resulting in an S-wave shadow zone, and Earth has a strong magnetic field.
Based on how Earth's atmosphere formed and evolved, select all of the correct statements from the following list.
Seawater dissolved much of the carbon dioxide in Earth's first atmosphere. The oxygen in Earth's atmosphere came from plant life. Earth is warmed by a natural greenhouse effect.
Which of the following pieces of evidence tell us about the makeup of Earth's core?
Shear waves cannot travel through Earth's center.
How do temperature and pressure vary with depth deep inside Earth?
Temperature and pressure both increase with depth.
What do the vesicular basalts tell us about the evolution of the lunar surface?
That it was once molten.
How did the moon achieve its synchronous rotation?
The Earth raises tidal bulges on the moon. As the moon rotated through these bulges, internal friction slowed the moon's rotation until it achieved tidal coupling.
This figure shows both P waves and S waves traveling through the interior of Earth. Which of the following is true?
The S wave cannot travel through the interior of a liquid.
What evidence do we have that Earth differentiated?
The curved paths of seismic waves indicate that the interior density of Earth is greater than can be explained by compression alone.
The lunar breccia shown here is formed by rock fragments bonded together by heat and pressure. How did this very common type of lunar rock form?
The explosive impact of meteoritic bodies formed the lunar breccias.
How can planets with no liquid water have a flooding stage?
The flooding is also by lava.
What do the features of vesicular basalts tell us about the evolution of the lunar surface?
The holes were once gas bubbles in the molten material, which means that the molten material was not under high pressure, and likely on the surface.
What distinguishes Earth's inner core from its outer core?
The inner core is solid, and the outer core is liquid.
How does the large-impact hypothesis explain the moon's lack of iron?
The iron core of the impacting object could have fallen into the larger body.
Based on the reasons why the moon is airless and cratered, and how it formed and evolved, select all of the correct statements from the following list.
The lunar surface is covered with a layer of dust. Currently, the formation of new impact craters on the moon is rare. Most were formed billions of years ago. The side of the moon facing Earth and the side facing away have different features. The moon does not have enough gravitational pull to retain an atmosphere.
With respect to the terrestrial planets, select all of the correct statements from the following list.
The mantles of terrestrial planets are made of dense rock. Earth's moon can be considered a terrestrial planet. The cores of terrestrial planets are metallic.
With a small telescope, we see that the moon has regions that are relatively smooth and others that are saturated with impact craters. What does this tell us about the moon's development?
The moon doesn't have much slow surface evolution.
For what reasons do we reject the condensation (double-planet) hypothesis of the moon's origin?
The moon has a much lower density than Earth and is very low in volatiles compared to Earth.
Why does the same side of the moon always face Earth?
The moon rotates in the same direction that it revolves and the moon's period of rotation is equal to its orbital period.
What is the effect of the tidal coupling between Earth and the moon?
The moon rotates once every revolution around Earth.
Why does the moon have large maria on the Earth-facing side, yet no large maria on the opposite side?
The moon's crust is thicker, or elevations higher, on the far side.
Why are so many lunar rock samples breccias?
The numerous impact event fragments produced a lot of brecciated rock.
Why do we suppose that the moon formed with a molten surface?
The oldest lunar rock samples are about 4.4 billion years old and composed of anorthosite, a mineral that crystallizes and rises to the top of a lava ocean.
Why would a decrease in the density of Earth's ozone layer cause public health problems?
The ozone layer blocks ultraviolet light from the sun, and ultraviolet light causes skin cancer.
How do astronomers know whether lunar highlands or lunar maria have older surfaces?
The presence of many more craters means that there has been more time for impacts in the highlands, so they are older surfaces.
Why doesn't the material in Earth's core vaporize?
The tremendous pressure from the weight of Earth's outer layers keeps the outer core liquid and the inner core solid.
What feature of vesicular basalts tells us what they do about the evolution of the lunar surface?
They are filled with holes.
Would you include the moon in a comparison of the terrestrial planets? Why or why not?
Yes: Earth's moon has many features in common with the terrestrial planets.
What type of tectonic zone is responsible for the Andes Mountains that are located all along the western side of South America?
a subduction zone
Where on Earth are two plates being pushed apart and new crust created?
along the center of the Atlantic Ocean and along the center of the Red Sea
Where are deep ocean trenches located relative to the moving plates of Earth's crust?
at subduction zones
A large fraction of lunar samples collected are
breccias.
Astronomers can estimate that the moon's crater Copernicus is older than Tycho because many more meteorites have struck its rim. How have astronomers estimated the actual age of parts of the Earth's moon in years?
bright ejecta blankets and rays
How do we find the relative ages of the moon's maria and highlands?
by counting the number of impact craters
Which hypothesis of lunar formation requires the occurrence of highly unlikely events?
capture
A large fraction of lunar samples collected are breccias. How were these rocks formed?
cementing together of fragments of earlier rocks by heat and pressure
What do we call the study of planets through contrast and comparison?
comparative planetology
Which hypothesis of lunar formation is ruled out by Earth and moon having different chemical compositions and density?
condensation
What creates Earth's strong dipole magnetic field?
convection in Earth's outer liquid iron-nickel core combined with Earth's rotation
What drives the moving plates of Earth's crust?
convection in Earth's rocky mantle
Which of these processes first occurred in the Earth's evolution?
core differentiation
Earth's interior can be divided up into four zones: the inner core, the outer core, the mantle, and the crust. Which of these zones has the lowest density?
crust
Which of these lists has the layers of Earth in order from the outside to the inside, from left to right?
crust, mantle, liquid core, solid core
Which is the first stage of planetary development?
differentiation
Which list below ranks the stages of the moon's history from left to right in the order in which they occurred?
differentiation, cooling, giant impact cratering, lava flooding, slow surface evolution
The interiors of small mass planets and satellites like Earth's moon cool ______ large mass objects of similar composition because they have ______.
faster than; more surface area per unit mass
Which hypothesis of lunar formation would require Earth to have spun much faster in the past than it does now?
fission
Which is not a conducting material in Earth's core?
gaseous carbon dioxide
Which type of atmosphere is Earth now believed never to have had?
hydrogen and helium
Which type of atmosphere is Earth now believed never to have had, and what evidence exists in this regard?
hydrogen and helium, since Earth formed rapidly and was heated by in-falling material, and this caused continuous outgassing from the cooling of molten material
Where did the first Apollo missions land?
in the maria
Where did the first Apollo missions land? What was the reason for this?
in the maria since it had the smoothest landing surface
Which hypothesis of lunar formation currently fits the data best?
large-impact
Rocks from the lunar crust are
low-density and igneous.
Which is an older surface?
lunar highlands
What kind of lunar terrain is shown in the above figure?
maria
Which of these atmospheric components is currently most abundant in the Earth's atmosphere?
nitrogen
What is the composition of Earth's atmosphere?
nitrogen and oxygen
Which of these atmospheric components became significant in the Earth's atmosphere most recently?
oxygen
What produced the oxygen in Earth's atmosphere?
plants
What erases the impact craters on Earth and is responsible for most of the landforms that we see?
plate tectonics and water and ice erosion
A Sense of Proportion: Arrange the following stages in the formation of the Moon's surface from earliest to latest:
slow cratering , late heavy bombardment , Magma ocean , flooding , solidification of crust
On the large scale, which of the four states of development of a planetary body could be termed "arrested development" in the case of the moon?
slow surface evolution
Which is the best description of the surface in the above figure?
smoother plains
Which is not a stage of planetary development?
subduction
What is suggested by rocks collected from the lunar crust?
that the moon formed in a molten state in which differentiation occurred
To study the oldest rocks, what sites on the lunar surface were considered of the most scientific interest?
the highlands
What sites on the lunar surface were considered of the most scientific interest? Why is this?
the highlands since they held more important geological features
When Earth formed, it melted and differentiated. What was the source of heat that melted Earth?
the infall of matter that formed Earth and the decay of radioactive elements
What single factor resulted in the moon today being so very much different than present-day Earth?
the moon's small size
How was Earth's atmosphere able to evolve to its current state?
the presence of liquid water and plants
