Test 3: Review Sheet

Short Answer Questions

1. More than 3,000 extra-Solar planets and over 2,000 extra-Solar planetary systems have been discovered in the last 23 years. What methods have been used to discover these planets? Desscribe the methods. What is the Doppler Effect? Describe how the Doppler Effect works. What is meant by wavelength? What is meant by frequency?
2. How do the general properties of the new planetary systems and planets compare to those of our Solar System? What do they tell us about how our Solar System formed?
3. What is the center of mass of a system? Roughly where is the center-of-mass of the Solar System located? Roughly how fast does the Sun orbit about the center-of-mass of the Solar System? For comparison, the orbital speed of the Earth is 30 kilometers per second.
4. What is meant by accretional heating, Radioactive heating, and Compressional heating?
5. What are the primary nuclei that heat the Earth? What is meant by half-life of an element?
6. Describe how one uses radioactive age dating to determine the age of a rock. What are the problems which arise when using radioactive age dating to measure the ages of rocks?
7. What is meant by Chemical Differntiation? What happens during chemical differentiation? Does this occur in all Terrestrial planets?
8. The layers of the Earth defined by their chemical composition are . Are these layers found in all Terrestrial planets?
9. The layers of the Earth defined by their mechanical properties are . What does it mean when we say a layer is plastic? Are these layers found in all Terrestrial planets?
10. List the ways astronomers probe the interiors of the Terrestrial planets. Which ways can be applied to a Terrestrial planet without leaving the Earth? Which ways require that one visit the object studied? Describe how magnetism arises. How does magnetism tell us about the interiors of Terrestrial planets? What has been the most useful probe for the interior of the Earth? What has been the best method for Mercury?
11. What are seismic waves? What are S waves? What are P waves? What is meant by S and P in the context of seismic waves? What is the Shadow Zone? What is meant by sound wave, longitudinal wave, shear wave, transverse wave? What wave travels faster, P waves or S waves? What are the approximate speeds of propagation of P waves and S waves? Roughly how long does it take for seismic waves to arrive at seismic on the opposite side of the Earth after an earthquake occurs? What kinds of waves arrive at the station? What is the weird terrain on Mercury? Which wave can propagate through solids, liquids, gas?
12. Why do large planets like the Earth have active geologies while small planets like Mercury and the Moon are geologically dead? Describe the argument used to show the relative rates at which large objects cool compare to small objects. The argument used to show that large planets cool more slowly than small planets lead to what are known as scaling laws. What is the most geologically active body in the Solar System? How does this result fit with our derived scaling law for the cooling of planets?
13. Today, Venus has a massive atmosphere of CO₂ while the Earth has an atmosphere of Nitrogen and Oxygen with little CO₂. What is a measure of the mass of an atmosphere?
14. What are maria? How were they formed? Where are they found? When were they formed? What are the general typess of surface features found on the Moon? Why do astronomers believe that the craters on the Moon (and by extension other planets) typically arise from impacts rather than volcanism? In particular, what is the explanation for why craters are circualr in shape rather than say in the shape of a trench or, say, an ellipse?
15. How are the ages of the surface features of Mercury estimated? Those on the Moon? Can these methods be applied to other Terrestrial planets? What (and when) is the period of heavy bombardment? What is a possible explanation for the period of heavy bombardment?
16. What is convection? Briefly, describe how it works. What is the relevance (importance) of convection when considering geology? What is conduction? What is radiative transport? Use the example of sitting around a campfire to show how each method works.
17. What are the general properties, the mases, radii, distances from the Sun, densities, chemical compositions of their interiors and atmospheres, ... of the Terrestrial planets? Besides Mercury, Venus, Earth, and Mars, what other Solar Systems may be lumped in with the Terrestrial planet group? 18. What is plate tectonics? How does plate tectonics work? What is evidence for plate tectonics? Why did it take decades for plate tectonics to be accepted by the scientific community after it was first proposed?
19. Compare oceanic crust to continental crust. How old is the oldest oceanic crust? How old is the oldest continental crust? Which type of crust covers more surface area on the Earth? Do both types of crust appear on all Terrestrial planets (exclude Mars from your answer)?
20. Describe what happens when different types of plates meet.
21. What are subduction zones? What are some examples of subduction zones on the Earth, in particular what is the Juan de Fuca plate and what is its relevance for the Pacific Northwest? What are transform faults? What are rift zones (what happeans at rift zones)? What gave rise to the Cascades, the Andes, the Himalayas?
22. What is meant by plumes? Describe how the Hawaiian islands were formed. Contrast shield volcanos to cinder cone volcnaos. Which type are found in the Cascades? On which Terrestrial planet are the tallest volcanos found? What determines the maximum height of a volcano? Are the large volcanos shield volcanos?
23. How has the surface of Venus been mapped? (This has been done despite the fact that Venus is heavily enshrouded by clouds.) How do we know that Venus has geologically active until fairly recently? What is the evidence that Venus is still geologically ative today? Did Magellan present evidence that Venus is still volcanically active? How would Magellan been able to show that Venus is geologically active today? What are the general types of terrain found on Venues? Are the large volcanos on Venus shield volanocs?
24. What are Lagrange points? Where will the James Webb telescopt, the replacemtn for Hubble, be placed? Where was Gaea placed? What are the Trojan asteroids? What are the Hildas? Where are they found? What is the gegenshein?
25. What features of the Moon suggest that it was formed via the Giant Impact mechanism? What is the Giant Impact mechanism?

Sample Multiple Choice Questions

1. A feature of the Jovian planets is that

a. they are composed primarily of methane and ammonia gas
b. they are larger than or around the size of Juptier
* c. they are composed primarily of hydrogen
d. they have relatively hard surfaces of water ice
e. they are all about the mass of Jupiter or larger

2. When we refer to the process of chemical differentiation, we are talking
about the process whereby

a. the planets form by first accreting iron and then adding layers of
the lighter layers sequentially
b. the dust grains and other particles sink to the mid-plane of the
Solar Nebula
c. the lithosphere rises so that it sits on top of the asthenosphere
* d. the heavier (more dense) elements sink to the center of the young
Earth
e. the Terrestrial planets form closer to the Sun than do the Jovian
planets

3. Which of the following facts must any theory for the formation of
the Solar System explain?

a. the nearly circular orbits of the planets
b. why the Jovian planets are so massive when compared to the
Terrestrials
c. the nearly co-planar orbits of the planets
d. the chemical compositions of the Jovian planets
* e. It should be able to explain all of the above facts

4. Of the following planets, which one's orbital characteristics differs
the most from the other listed planets?

* a. Mercury
b. Earth
c. Uranus
d. Neptune
e. Jupiter

5. Which of the following is a characteristic of the
Terrestrial planets?

a. high density
b. solid outer layers (hard surfaces)
c. small sizes (diameters < diameter of the Earth)
d. they are not very far from the Sun (a < 2 A.U.)
* e. All of the above are charateristics of the Terrestrial planets.

6. The chemical composition of the atmosphere of Mars is
most similar to the atmosphere of

a. Jupiter
* b. Venus
c. the Earth
d. the Moon
e. Mercury

7. The plastic region in the interior of the Earth where energy is
transported by convective motions is the

a. core
b. mantle
* c. asthenosphere
d. lithosphere
e. crust

9. The currently accepted theory for the origin of the Moon

a. proposes that the young Earth spun rapidly and ejected the Moon
from its surface
b. proposes that the Moon was formed outside of the Solar System and
was subsequently captured by the Sun
* c. proposes that the young Earth was struck by a Mars-sized object
which led to the formation of the Moon
d. proposes that Earth and Moon formed independently but from one
collapsing gas cloud

10. A key to understanding why there is a large difference between
the masses of the Jovian planets and the Terrestrial planets is

a. that water was able to exist in solid form (ice) only near and
beyond the orbits of the Jovian planets
b. the fact that only in the outer Solar System could forming planets
capture and hold hydrogen and helium
c. rocky material could only be in solid form beyond the orbits of the
Jovian planets
* d. only a and b
e. a, b, and c

11. We expect the Earth's core to be more dense than its crust because

a. in the early stages of the Earth's formation, its interior was molten (or at least, it was soft)
b. the density of material in the crust is less than the overall
average density of the Earth
c. any material becomes more dense as it is compressed by the weight of
the material lying above it
* d. all of the above are correct
e. only a and b are correct

12. The light-colored regions on the Moon are

a. the highlands and are thought to be the youngest features on the
Moon
* b. the highlands and are heavily cratered
c. the maria and are thought to be old; ages up to 4.6 billion years
d. the maria and are thought to be around 3.2 - 3.8 billion years old
e. wind-swept plains formed early in the Moon's history

13. The study of the Moon's surface and rocks has revealed that

a. a short period of intense bombardment occured around 1 billion years
ago
b. the cratering history of the Moon is anomalous in that it is
different from what we know about the cratering rates of the
other planets
* c. the rate of impacts was very high 4 billion years ago but then
precipitously to its current levels
d. the far side of the Moon has never been struck by objects as large
as the ones which struck the near side of the Moon (and formed the
maria)

14. The relative ages of the regions on Mars can be inferred from

a. the heights of their volcanos
b. the lengths of their canyons (e.g., Valles Marineris)
* c. the number of craters
d. the sizes of their largest craters
e. the number of volcanos they contain

15. Active geology on a planet

a. requires the existence of a lithosphere
b. requires an extensive and thick atmosphere
c. only occurs when the planet has a sizable moon
* d. will only occur if the planet has a hot interior
e. will only occur on smaller planets, in general

16. On the Earth, the oceanic plates

a. are less dense than the continental plates
* b. are re-cycled roughly every 100 - 200 million years
c. contain some of the oldest surface features found on the Earth
d. are thought to be composed mainly of iron and nickel
e. tend to float on top of the continental plates

17. Continental drift (plate tectonic activity) may be driven by

a. strong winds
b. ocean currents
c. earthquakes
d. volcanism
* e. convection

18. The Tharsis region on Mars

a. shows some of the oldest surface features on Mars
b. lies for the most part below the sea level on Mars
* c. is a region of very recent volcanism
d. contains both heavily cratered and relatively uncratered regions
e. is strong evidence that, in the past, Mars showed extensive plate
tectontic activity

19. The Martian surface shows a striking asymmetry between its
northern and southern hemispheres. The differences show up

a. in the composition of the atmosphere above each region
* b. in the elevations of the regions
c. in the number of continents each contains
d. in the amount of plate tectonic activity each exhibits
e. All of the above are examples of the striking differences between
the two hemispheres

20. Which of the following statements about the surface of Venus is correct?

a. The surface of Venus is thought to be ancient, 4.6 billion years old
b. There is an overabundance of craters with diameters less than 30
km on Venus
c. Most of the surface of Venus is fairly young, only 3 billion
years old
d. The surface of Venus is covered primarily by continental-type
regions
* e. Venus's lithosphere is thought to be weaker and more pliable than
the Earth's lithosphere

21. The surface of Mercury is more like that of _____ while its
interior is more like that of _____ .

a. the Moon; Jupiter
b. Mars; Venus
* c. the Moon; the Earth
d. Mars; Jupiter
e. Mars; the Earth

22. The atmospheric pressure of a planet

a. is a measure of the surface temperature on the planet
* b. is a measure of the mass contained in the atmosphere of a planet
c. is a measure of the temperature of the gas around the planet
d. tells you the composition of the atmosphere of the planet

25. Which of the following is a true statement about an S wave?

a. It is a wave whose disturbance is in a direction parallel to its
direction of propagation
* b. An example of an S wave is a wave travelling down a rope
c. An example of an S wave is a compression wave moving along a spring
d. S waves can only be produced by earthquakes.
e. S waves can only propagate along the surfaces of planets

26. Compared with the side of the Moon facing the Earth, the lunar backside
has

a. more maria
b. substantially fewer craters
c. substantially fewer mountain ranges
* d. a thicker crust
e. an active volcano!

27. Which of the following facts must any theory for the formation of the
Solar System explain?

a. the orbital properties of the Galilean moons of Jupiter
* b. the existence of general classes of planets
c. the origin and properties of the Earth's moon
d. the origin of the atmospheres of the Terrestrial planets
e. Venus rotates in the opposite sense that it revolves about the Sun

28. The Solar System is thought to be

a. 100 - 200 million years old
b. 46 million years old
* c. 4.6 billion years old
d. 10 billion years old
e. 300 - 800 million years old

29. Which of the following Terrestrial planets shows strong evidence for past
or present plate tectonic activity?

a. Venus
* b. Earth
c. Mars
d. only the Earth and Venus
e. Venus, Earth, and Mars

30. The majority of the surface features on Mercury were formed via

a. plate tectonic activity
b. erosion
c. volcanism
* d. impacts
e. a few very large impacts due to asteroid-sized objects

31. What explains the lack of small impact craters (less than 1.4 km)
on Venus?

a. objects of the size needed to produce such craters never reach the
surface of Venus due to Venus's strong magnetic field
* b. the thick atmosphere burns up most objects which produce craters
of this size
c. small impact craters have been eroded by water and wind
d. the statement is incorrect -- there are many such small craters
on Venus

32. A measurement of the density of a planet can tell us

* a. the rough composition of the planet
b. the age of the planet
c. the mass of the planet
d. the size (diameter) of the planet
e. All of the above can be deduced from only the density of a planet.

33. The heat which melted the young Terrestrial planets
came primarily from

a. nuclear fusion reactions similar to those that heat the Sun
b. the sunlight absorbed from the young Sun
c. the decay of radioactive elements
* d. the high-energy impacts (accretion) of planetesimals
e. the energy produced by the burning of fossil fuels

34. Based on the composition of the Earth, we define the following regions
in the interior of the Earth (in order of increasing distance from the
center of the Earth)

a. troposphere, mesosphere, stratosphere
* b. core, mantle, crust
c. mantle, core, crust
d. lithosphere, hydropshere, asthenosphere
e. core, asthenosphere, lithosphere

35. Near subduction zones, we expect

a. to find large changes in the level of the oceans
* b. to find active volcanism
c. to see the formation of island chains (like Hawaii)
d. to observe the creation of new continental crustal material
e. to see sea-floor spreading

36. Due to the continuous creation of crustal material

a. the Earth is growing in diameter by around 2 - 3 cm per year.
b. the land masses (continents) are being continuosly destroyed
c. the Earth is getting more massive as time goes by
* d. the ocean basins are replaced every few hundred million years
e. the sea level is rising by around 2 - 4 cm per year

37. The mountains on the Moon are

a. strong evidence for the recent collision of continental plates
b. caused by hot-spots in the mantle of the Moon
* c. created by the impacts of large objects on the Moon
d. evidence of extensive volcanism in the early history of the Moon
e. evidence that the Moon was once part of the Earth

38. We know that the Lunar maria formed after the Lunar highlands because

* a. the highlands are more heavily cratered than are the maria
b. the maria are at lower elevations than are the highlands
c. there is a lack of maria on the far side of the Moon
d. the highlands are darker in color than are the maria
e. most of the Moon is covered by highland regions

39. Of the following planets, which has the largest iron core relative to its
overall mass?

* a. Mercury
b. Venus
c. Earth
d. Moon
e. Mars

40. In astrometric searches for other solar systems,

a. we search for transits of planets in front of candidate stars (eclipses)
b. we search for small periodic changes in the wavelengths of the
radiation from nearby stars
c. we search for small periodic changes in the pulsation period of
pulsars
* d. we search for small periodic changes in the positions of stars
e. we search evidence of young forming stars

42. Terrestrial planets start with different chemical compositions than Jovian
planets because

a. they formed in parts of the Solar Nebula which had radically
different chemical compositions
* b. of the high temperatures in the inner solar nebula
c. Terrestrial planets are smaller than the Jovian planets
d. Jovian planets have stronger magnetic fields
e. Jovian have many moons which altered their atmospheres

43. Which of the following processes is likely to have been the most important
in the formation of the Earth's atmosphere?

* a. vaporization of impacting comets
b. gravitational capture of surrounding gases
c. respiration of living organisms
* d. outgassing from its interior
e. radioactive decay of heavy elements such as uranium

44. The surface of Venus is around

a. 4.6 million years old
b. several trillion years old
c. 4.6 billion years old
* d. 300 - 800 million years old
e. 100 - 200 million years old

45. Which of the following statements best describes the formation of the
Lunar maria?

a. melting and crust solidification followed by impacts
b. massive volcanism and the subsequent cooling of the crust
* c. large impacts followed by volcanism
d. massive volcanism followed by large impacts
e. uplifts and subsequent collapses of the lunar crust

46. Modern data indicates that Venus

a. has extensive, rapid, and current continental drift
b. has never had volcanic activity
c. is covered mainly by continent-like regions (highlands)
* d. may have had recent volcanic activity
e. is covered by a layer of water to a depth of roughly 2 -3 kilometers

47. A major reason for the large size of the volcanos on Mars is

* a. the probable lack of continental drift on Mars
b. the rapid motion of continental plates on Mars
c. the large number of volcanos on Mars
d. the small size of Mars

48. Based on the appearances of the Moon, Mercury, and the Earth, plus
knowledge of their interiors, we might conclude that

* a. Mercury and the Moon have changed little in the last 3 billion years
while the Earth is evolving continuously
b. both Mercury and the Earth are still evolving, while the
Moon is dead
c. All three of the objects are geologically active today
d. The surface on all three of the objects may be considered permanent,
that is, they are unchanging

49. Large quantities of rock (new crustal material) are emerging from the
mantle

a. along the tops of continental mountain ranges (such as the
Himalayas)
b. along the boundaries between continental and oceanic plates
c. along the major continental rivers (such as the Mississippi)
where the crustal plates are the thinnest
* d. along the rifts found between oceanic plates