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Test 2
Astronomy 121

Sign the test form and the Scantron form. Include your student identification number on the Scantron form and bubble-in the appropriate circles. When you are finished with the exam, hand in both the Test form and the Scantron form at the front desk.

50 Multiple Choice Questions at 2 points per question. Select the best answer

1. Astronomers have discovered ________ .

a. only two extra-Solar planetary systems like our own
b. more than one-hundred planetary systems like our own
c. many Earth-like planets, but only a few Jupiter-like planets
*d. that planetary systems are very common in our galaxy
e. that planetary systems all contain at least one planet with condtions hospitable to life as we know it

2. Listed below are dynamical regularities shown by the planets in our Solar System. Of these, which is clearly NOT true for the newly discovered planets?

a. Planets orbit about their star in the counter-clockwise sense, as viewed from the North Celestial Pole
b. Planets orbit about their star in roughly the same plane
c. Planets generally rotate on their axes in the counter-clockwise sense, as viewed from the North Celestial Pole
*d. Planets orbit their star in nearly circular orbits
e. All of the above have been observed to be properties of the newly discovered planets.

3. The conditions in the current atmosphere of Mars are _______ .

a. such that water cannot exist in any form on the surface of Mars
b. such that one expects a substantial stratosphere to form
*c. such that liquid water cannot exist on the surface of Mars
d. such that one expects that life could exist near the equator on Mars during the summer months

4. When Mars was young, its climate was believed to be similar to the current climate of the Earth. Its atmosphere then evolved to what it is today. The current wisdom says that this was because of _______ .

a. the impact of a large object which caused the atmosphere to boil-off
*b. the lack of large-scale plate tectonics
c. a stage of intense volcanism, as has also been postulated for the Moon
d. the rapid cooling of the interior of the planet
e. the depletion of the Martian ozone layer

5. In the future when we visit each Terrestrial planet, we will construct a network of seismic detectors on each planet so that we may study their interiors. In this future time after an earthquake occurs, an S-wave Shadow Zone would not be detected on _____ .

*a. Mercury
b. Venus
c. Earth
d. All of the above would exhibit a Shadow Zone

6. Of the following, which suggests that the Martian atmosphere was much thicker just after Mars had formed?

a. outflow channels
b. splosh craters
c. the permafrost layer
*d. the sinuous dried riverbeds
e. the northern residual polar cap

7. The searches for extra-Solar planets that have yielded the most discoveries of planets were based on the detection of _____ .

a. annual trigonometric parallax
*b. Doppler shifts
c. epicyclic motions
d. gravitational micro-lensing
e. transits of planets across stars

8. The Jovian-like planets found in extra-Solar planetary systems _____ .

a. are all located at distances larger than 3-4 A.U. from their stars
b. all have orbits with very small eccentricities
c. were mainly found as they transited their stars
d. do not seem to obey Kepler's 3rd Law of Planetary Motion
*e. in many instances appear to be too close to their stars; well within the distance where water ice solidifies

9. The discovery of extra-Solar planets _____ .

*a. has occured primarily over the last ten years
b. has been going on for the last forty years; the discoveries were triggered by the space program
c. has taken place slowly but steadily over the last 2,000 years
d. was first made by Galileo and has continued smoothly since then
e. started with Aristarchus, but then stopped until the 18th century when the first large telescopes were constructed

10. Oceanic basins make up about _____ of the surface of the Earth.

a. 5 %
b. 25 %
*c. 55 %
d. 80 %
e. 95 %

11. The core, mantle, and crust of the Earth are defined by _____ .

*a. their chemical composition
b. their mechanical properties
c. their temperatures
d. their ages
e. their thicknesses

12. Measuring the atmospheric pressures on Venus and the Earth allows one to _______.

a. determine the relative chemical make-ups of the two planets
b. determine the depths of the oceans on the two planets
c. determine the escape velocities of the two planets
*d. determine the masses of the atmospheres of the two planets
e. determine whether an ozone layer exists around both planets

13. P waves are seismic waves. P waves ______ .

a. can only travel through solid material
b. are examples of transverse waves
c. are detected by Doppler shifts
*d. can travel through liquids
e. can only travel along the surface of the Earth

14. The majority of the surface features on Mercury formed through _______ .

a. plate tectonic activity
b. wind and water erosion
c. volcanism
*d. impacts
e. uplifts

15. Near a subduction zone, 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

16. Magnetic fields __________ .

a. tell us the chemical composition of the core of the Earth
b. tell us that the Moon is much younger than the Earth
c. suggest that Venus at one time had plate tectonics
*d. suggest that the core of the Earth is molten
e. are produced by radioactive decay

17. The asthenosphere is _________.

*a. the layer where heat is transported by convection
b. the layer just below the ozone layer in the atmosphere
c. the molten iron core at the center of a planet
d. the lower part of the lithosphere
e. the layer that contains the oceans

18. During the Final Heavy Bombardment, we believe _____ .

a. that the Moon was formed
*b. that the basins that formed the maria were produced
c. that the Andes and the Himalayas were formed
d. that the impact that may have led to the extinction of the dinosaurs occurred
e. that the crust of the Earth formed

19. A subduction zone is _____ .

a. where a continental plate runs into another continental plate
b. a region where crust is created
*c. a region where crust is destroyed
d. an uplift, like the coronae and arachnoids on Venus
e. the liquid part of the Earth's core

20. Large impacts, such as the one that supposedly led to the extinction of the dinosaurs, currently happen _____ .

a. every ten thousand years or so
b. every million years or so
*c. every 100 million years or so
d. every billion years or so
e. every 4.6 billion years or so

21. The seismic waves that travel most quickly through the Earth are _____ .

*a. P waves
b. S waves
c. R waves
d. P and S waves travel at the same speed

22. The largest volcano(s) in the Solar System _____ .

a. are shield volcanos
b. are found on Mars
c. are similar to those that produced the Hawaiian islands
d. is Olympus Mons
*e. All of the above correct

23. Seismology has been used to probe the interior of _____ as well as for the Earth.

a. Mars
b. Venus
*c. the Moon
d. Mercury
e. Seismology has been used on all of the above planets and moon

24. The current atmospheres of Terrestrial planets are _______ .

a. the result of outgassing
b. the capture of many comets
c. the gases captured originally from the Solar Nebula
*d. A combination of a & b
e. The combination of a, b, & c

25. The majority of Venus's surface is best described as _______ .

*a. rolling plains
b. continental, highland regions
c. lowlands
d. oceanic basins
e. uplifts similar to the Tharsis Bulge

26. Oceanic plates on the Earth _______.

*a. move at rates of 2-4 centimeters every year
b. make up the plastic portions of the lithosphere
c. are less dense than the Continental plates
d. flow easily because they are molten iron
e. are found only near the poles of the Earth

27. The Tharsis region on Mars _______ .

a. is a large impact basin that lies, for the most part, below sea level on Mars
b. is the oldest region on Mars
c. was formed by a large impact, similar to the one that formed our Moon
d. contains both heavily cratered and relatively uncratered regions
*e. was likely formed by an uplift of Mars's crust

28. An isotope of Aluminum (Al) decays to Magnesium Mg with a half-life of 720,000 years. A rock contains 16 Al atoms and 112 Mg atoms. If the rock was orginally pure Al, how old is the rock?

a. We cannot tell from the information given.
b. 720,000 years
c. 1,440,000 years
*d. 2,160,000 years
e. 2,880,000 years

29. The bulk of the carbon dioxide initially present in the atmosphere of the young Earth _______ .

a. has been lost to space
b. is contained in green plants and plankton
*c. is tied up in the crust of the Earth
d. is contained in the oceans of the Earth
e. is contained in the polar caps

30. The light-colored regions on the Moon are _______ .

*a. the highlands, the oldest an most heavily cratered regions on the Moon
b. the maria, the Lunar oceanic crustal plates
c. the maria, mountainous regions produced right after the Moon formed
d. the large plains coevered by dust
e. the mountain ranges produced during the era plate tectonics was active on the Moon

31. Of the following statements, which is NOT correct?

a. The surface of Venus is young, less than 1 billion years old
b. There is an underabundance of craters with diameter less than 30 km on Venus
*c. The surface of Venus is covered primarily by continental-type regions
d. The surface of Venus may show signs of recent geological activity
e. There are many shield volcanos on Venus

32. Whether a planet was able to attract and hold onto an atmosphere when it was formed was determined by _____ .

a. the temperature of the gas near it and whether the Sun had turned on
b. the gravity of the planet and whether the Sun had turned on
*c. the temperature of the gas near it and the gravity of the planet
d. the gravity of the planet gas and whether water could be frozen
e. the temperature of the Sun and whether water could be in liquid form

33. The Valles Marineris _____ .

a. was likely formed by water erosion, similar to how the Grand Canyon formed
b. was likely formed by the impact of a protoplanet that cracked Mars's lithosphere
c. is likely the remains of a large rift zone
d. is likely the remains of ancient subduction zone formed by Mars's only oceanic plate
*e. was formed by cracking that occurred during the formation of the Tharsis Bulge

34. The Lunar maria _______ .

*a. are the result of the flooding of large impact basins
b. have much higher crater densities than the surrounding regions
c. are spread uniformly over the surface of the Moon
d. are unique to the Moon; they have no counterparts on other planets
e. All of the above are correct statements about the lunar maria

35. The property of a Terrestrial planet that determines whether it will have active geology today is _____ .

a. its rotation period
b. its distance from the Sun
c. whether it has a large moon
*d. its diameter
e. the mass of its atmosphere

36. The Hawaiian island chain _______ .

a. is strong evidence for the recent collision of continental plates
*b. was caused by a hot-spot in the mantle of the Earth and crustal motion
c. was created by a series of impacts of large objects
d. is evidence that the Moon was once part of the Earth
e. was formed in a manner similar to the Andes in South America

37. The interior of the Earth was heated by _____ .

a. accretion of large bodies
b. radioactive decay
c. self-compression by gravity
d. only a & b
*e. a, b, & c

38. During Chemical Differentiation in the Earth, _____ .

a. the primary atmosphere of the Earth escaped
*b. the elements in the interior separated; dense elements sank and light elements rose
c. the crust and segmented plates of the Earth formed
d. the oceans and ocean basins formed
e. the different layers of the atmosphere formed

39. The key to understanding why Venus's atmosphere evolved so differently than did the atmosphere of the Earth is _____ .

*a. liquid oceans could not form on Venus
b. that a large impact occured early in Venus's evolution that stripped off Venus's water
c. that fewer comets have struck Venus over its lifetime
d. Venus's apparent lack of plate tectonics
e. is the heat supplied by Venus's large number of active volcanos

40. The Earth's current atmosphere is _____ .

a. primarily carbon dioxide and water
b. primarily water with trace amounts of carbon dioxide
*c. primarily nitrogen, but with a significant amount of oxygen
d. primarily oxygen with trace amounts of carbon dioxide
e. primarily oxygen with significant amounts of carbon dioxide and water

41. The _____ is(are) evidence for recent volcanism on Venus.

a. lightly cratered lava flows seen on Venus's surface
b. changing levels of Sulfur Dioxide found in Venus's atmosphere
c. radio outbursts seen in Venus's atomosphere
d. only a& b
*e. a, b, & c

42. The large earthquakes experienced in California every one hundred years or so, are caused by slips that occur between the _____ plates.

a. North American and Juan de Fuca
b. North American and South American
*c. Pacific and North American
d. Pacific and Juan de Fuca
e. South American and Juan de Fuca

43. Venus is covered by a thick cloud cover that prevents visible light from reaching its surface. The Magellan spacecraft mapped the surface of Venus by bouncing a beam of ______ off the surface of Venus, employing a technique known as _____ .

a. x-rays -- radar ranging
*b. microwaves -- radar ranging
c. x-rays -- gravitational microlensing
d. microwaves -- gravitational microlensing

44. Strong evidence that the Moon was geologically active in the past comes from the ____ .

a. mountains in the highland regions
b. lack of maria on the farside of the Moon
c. existence of the continent-like highland regions
d. light color of the highland regions
*e. maria seen on the Moon

45. The current atmospheric pressures on Venus, Earth, and Mars are in the rough ratio _____ .

a. 1 : 1 : 1
b. 1 : 100 : 0.01
*c. 100 : 1 : 0.01
d. 1 : 1 : 0.01
e. 100 : 1 : 2

46. Large earthquakes hit the Northwest every five hundred years. They are the result of the _____ formed where the _____ .

*a. subduction zone -- Juan de Fuca and North American plates collide
b. subduction zone -- Pacific and North American plates collide
c. rift zone -- Juan de Fuca and North American plates collide
d. rift zone -- Pacific and North American plates separate
e. transform fault -- North American and Pacific plates collide

47. We believe 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

48. The portion of the northern Martian polar cap that remains in the summer is composed of _____ while the portion of the southern polar cap that remains in the summer is composed of _____.

a. water ice, water ice
b. carbon dioxide ice, carbon dioxide ice
*c. water ice, carbon dioxide ice
d. carbon dioxide ice, water ice
e. water ice and frozen hydrogen, water ice

49. Lowlands and plains are plentiful in the Martian _____ hemisphere; craters and highlands are plentiful in the Martian _____ hemisphere.

a. northern, northern
b. southern, southern
c. southern, northern
*d. northern, southern

50. The stratosphere is ________ .

a. where the ionosphere is located in the Earth's atmosphere
b. where the weather on the Earth is generated
*c. the layer where Ozone is found in the Earth's atmosphere
d. where the water on the Earth is in its liquid form
e. All of the above are correct endings for the above statement.