PH109 Exploring the Universe, TEST #2, Fall, 1998

PH109 Exploring the Universe, TEST #2, fall, 1998

NAME______

Please indicate the best answer to the following questions on the answer sheet provided. All questions are worth 2 points unless indicated otherwise.

1. What is (are) the major source(s) of tides on Earth? a) Moon only, b) Moon and Sun, c) Moon, Sun, and Jupiter, d) Moon and other planets, but not the Sun

2. What are the two major greenhouse gases in Earth's atmosphere? a) oxygen and nitrogen, b) nitrogen and carbon dioxide c) carbon dioxide and methane, d) water vapor and carbon dioxide

3. One of the following factors, along with temperature, determines whether a body will retain an atmosphere of a given composition. a) size, b) distance from the sun, c) escape speed, d) rate of rotation, e) magnetic field

4. What is the primary ingredient in the Earth's atmosphere? a) Nitrogen, b) Oxygen, c) Nitrogen and oxygen in equal amounts., d) Hydrogen, e) Carbon dioxide

5. The presence of a magnetic field is a good indication that: a) A large amount of magnetic material, probably brought to Earth during a meteorite fall, is buried somewhere near the North Pole. b) A quantity of liquid metal is swirling around in the Earth's core. c) The Earth is composed mostly of iron. d) The Earth is completely solid.

6. The oldest rocks on Earth are dated to be: a) Nearly a billion years old., b) Nearly 4 billion years old. c) Nearly 10 billion years old., d) No more than about 5,000 years old.

7. Name two places on Earth where convection is operating on a large scale, creating natural phenomena that are important features for life on Earth. a) In the atmosphere and the mantle., b) In the two Van Allen belts. c) In the crust and the exosphere., d) all of the above, e) none of the above

8. The Moon's atmosphere is composed of: a) Nitrogen and oxygen., b) Carbon dioxide., c) Hydrogen and helium., d) Methane and ammonia., e) It has no atmosphere.

9. The rate of cratering on the lunar highlands helps to show that: a) They are younger than the maria., b) They are older than the maria. c) They are about 1 billion years old., d) They are about 2 billion years old.

10. What theory of the Moon's origin is favored by most astronomers today? a) The Moon formed as a separate object near Earth and at about the same time. b) The Moon formed far from Earth and was captured by its gravity. c) The Moon originated as material torn from the young, mostly molten Earth by centrifugal or tidal forces. d) The Moon originated as material torn from Earth by the collision of a large Mars-sized body.

11. Large asteroids are thought to collide with Earth: a) A few times in every million-year period., b) About once a century. c) Once every billion years., d) Never; only comets are thought to collide with Earth. 12. What causes a meteor shower? a) Earth crosses the orbit of a comet, and this orbit is littered with debris. b) Earth intercepts a stray swarm of asteroids. c) Earth encounters the asteroid belt. d) A small constellation of dying stars disintegrates.

13. The Oort Cloud is thought to be: a) The cloud of gas and dust from which our solar system formed. b) A cloud of debris that occasionally encounters the Earth, causing a meteor shower. c) A cloud of comets surrounding the solar system. d) A cloud of asteroids moving between the orbits of Mars and Jupiter.

14. The orbits of most asteroids: a) Lie beyond the orbit of Mars., b) Cross the orbit of Mars. c) Cross the orbit of Earth., d) Bring them near the Sun; these asteroids are called Sungrazers.

15. What causes the bright flash of light as a meteor plunges through the atmosphere? a) The meteor glows white hot., b) Lightning sparked by the meteor's passage. c) Air molecules ionized by the friction of the meteor's passage. d) All of the above., e) None of the above.

16. Which of the following has an icy composition? a) asteroids, b) meteors, c) comets, d) meteoroids, e) moons of the terrestrial planets

17. How do the densities of the terrestrial and jovian planets compare? a) They all have similar densities. b) The jovian planets generally have higher densities than terrestrial planets. c) No generalization can be made; each planet is quite different from the next. d) Comparisons are useless because the jovian planets are so much larger than terrestrial planets. e) The terrestrial planets have higher densities than the jovian planets.

18. In light of modern solar system theory, why do the orbits of the planets all lie in nearly the same plane? a) The Sun's gravity forced them into these orbits. b) The angular momentum of the solar system was kept to a minimum this way. c) The early solar nebula flattened into a disk. d) This happened purely by chance.

19. What factor caused different planets to form out of different types of material? a) The angular momentum of the forming planet. b) The quantity of dust particles in the solar nebula. c) The variation in temperature throughout the solar nebula. d) all of the above e) none of the above

20. What is the process of accretion? a) Growth of an object by the accumulation of matter. b) The breakup of large objects by violent collisions with other similar-sized objects. c) The period of time during which the Sun swept away all the excess material in the solar nebula. d) It is the process by which the solar nebula became heated during its collapse.

21. Mercury's surface resembles that of what other world? a) Earth., b) The Moon., c) Mars., d) Venus., e) Pluto. 22. Mercury experiences extreme highs and lows in temperature between day and night because: a) Mercury is so close to the sun. b) Mercury lacks a blanket of atmosphere. c) The planet's surface is undergoing a runaway greenhouse effect. d) Mercury has a low inclination.

23. The presence of a magnetic field on Mercury is surprising because: a) The planet is low in iron., b) The planet rotates so slowly. c) Planets rarely have magnetic fields., d) The planet is so close to the sun.

24. What is the main constituent of the atmosphere of Venus? a) Oxygen., b) Nitrogen., c) Hydrogen., d) Carbon dioxide.

25. The lack of a magnetic field on Venus probably stems from the planet's: a) Nearness to the Sun., b) Extremely thick atmosphere. c) Slow rotation., d) High surface temperatures.

26. What effect does the Greenhouse effect have on the surface environment of Venus? a) Little or no effect., b) About the same as on Earth. c) It has reduced the surface temperature by about 30 degrees Celsius. d) It has raised the surface temperature by hundreds of degrees Celsius.

27. How long is a day on Mars? a) About equal to one Earth day., b) Three Earth days. c) Mars rotates once for each revolution around the Sun., d) About 10 hours.

28. Why is one hemisphere of Mars believed to be older than the other? a) One hemisphere is darker., b) One hemisphere is more heavily cratered. c) One hemisphere is lower., d) One hemisphere leans more away from the Sun.

29. Why does Mars have seasons? a) Its orbit is circular. b) It rotates only a few times during each orbit around the Sun. c) Mars has a very elliptical orbit that brings it very close to the Sun during summer and far from the Sun during winter. d) Its axis is tilted relative to its orbital plane.

30. Why is Mars red? a) Dust storms on the planet have blasted the planet so fiercely that the rocks have reddened. b) The planet's surface undergoes a process by which rust forms. c) Sulfuric acid rain etched a reddish color into surface rocks. d) The ancient volcanoes poured out vast plains of molten red lava which has now solidified.

31. Venus and Mars probably evolved differently from Earth because: a) They are slightly bigger than Earth., b) They are more massive than Earth. c) They formed sooner than Earth., d) They orbit at different distances from the Sun.

32. Who discovered Uranus? a) Galileo, b) William Herschel, c) Johann Galle, d) John Adams and Urbain Leverrier

33. What are the most abundant gases in Jupiter's atmosphere? a) methane and hydrogen, b) methane and ammonia, c) hydrogen and ammonia, d) hydrogen and helium 34. How do the escape velocities of the jovian planets compare to the terrestrial planets? a) The jovian planets have much higher escape velocities. b) There is little variation among the planets. c) The escape velocities vary greatly from planet to planet but there are no general differences between jovian and terrestrial planets. d) The terrestrial planets have higher escape velocities.

35. If you could find a bathtub big enough for Saturn, the planet would: a) Precipitate more helium., b) Float., c) Leave a ring., d) Sink.

36. The structure of Saturn and its atmosphere is most similar to: a) Jupiter., b) Uranus., c) Neptune., d) Triton. 37. For which planet is it possible for the Sun to remain overhead for years at a time at either pole and for the equator to receive almost no sunlight for years? a) Uranus., b) Neptune., c) Pluto., d) Triton.

38. What is the order of the four Galilean moons of Jupiter in increasing distance from the planet? a) Ganymede, Callisto, Io, Europa, b) Callisto, Io, Europa, Ganymede c) Io, Europa, Ganymede, Callisto, d) Europa, Ganymede, Callisto, Io

39. What is Io's atmosphere made of? a) sulfur dioxide, b) methane, c) ammonia, d) nitrogen

40. Planetary rings are: a) part of the accretion process, b) held in place by magnetic fields c) left over debris from a destroyed moon, d) solid sheets of material in orbit around the planet

41. (10 points) Describe each of the terrestrial planets in the solar system, indicating a few each one's observable properties.

42. (10 points) Explain in general terms how we think our solar system formed.