Astronomy I Exam II Sample NAME:

Transcription

1 NAME: Part I: Multiple Choice (2 points. ea.) choose the best answer 1. Which of the following occurs because of the orbit of the Earth about the Sun and cannot be accounted for in geocentric models of the solar system? (A) Coriolis effect. (B) The phenomena of day and night. (C) the aberration of starlight and stellar parallax. (D) planetary retrograde motion. 2. The age of the earth is estimated at roughly: (A) less than 2 thousand years. (B) 4.6 thousand years. (C) 4.6 million years. (D) 4.6 billion years. 3. Sea-floor spreading and continental drift are believed to be caused by which of the following? (A) tides. (B) convection currents in the mantle. (C) changes in the Earth's magnetic field. (D) shrinkage of the crust as the Earth cools. 4. What is the primary source of waves that allows scientists to study the interior of the earth (by effectively taking a sonogram of the earth's interior)? (A) hurricanes. (B) thunder. (C) earthquakes. (D) aurora. 5. What is the origin of the Earth's magnetic field? (A) pockets of solar magnetism captured from the solar wind. (B) permanent magnetism left over from the formation of the Earth. (C) the flow of ionized gases in the Earth's upper atmosphere. (D) convection currents in the Earth's molten iron core which create an electric dynamo. 6. The process by which gravitational forces separate material of different densities within the planetary interior is called (A) Subduction. (B) Transvection. (C) Homogenization. (D) Differentiation. 7. What produces auroras? (A) chemical reactions in the upper atmosphere. (B) meteors. (C) collisions of high energy particles with atmospheric gas. (D) reflection of sunlight by high clouds 1

2 8. A total lunar eclipse occurs when the Moon enters the Earth's (A) Umbral Shadow (B) Van Allen belts (C) Equatorial plane (D) Saros Cycle 9. The Moon always faces the Earth because of (A) tidal locking. (B) Kepler s third law. (C) retrograde motion of the Moon s orbit. (D) electromagnetic coupling between the Earth and lunar magnetic fields. 10. The surface of the Moon (A) at one time had running water. (B) has changed little in the past 2-3 billion years. (C) has an atmosphere similar to the Jovian planets. (D) acquired its present appearance about 100 million years ago. 11. How can craters tell us about the ages of surface regions of planets? (A) Crater density increases with time, so older surfaces have more craters. (B) Impacts produce carbon 14, which can be dated by radioactive methods. (C) Material blasted from the craters sometimes reaches Earth and can be dated. (D) Craters shrink in size at a predictable rate 12. The dark, relatively smooth regions of the Moon s surface are the (A) craters. (B) maria. (C) terrae. (D) ejecta blankets. 13. Which of the following is now thought to be the most likely way in which the Moon formed? (A) giant impact model. (B) binary accretion model. (C) capture model. (D) fission model. 14. In which of the following circumstances can Mercury be observed? (A) setting at sunset. (B) near the horizon at noon. (C) high in the sky at midnight. (D) setting at sunrise. 15. Which of the following objects has a surface which most nearly resembles that of Mercury? (A) Venus. (B) the moon. (C) Earth. (D) Io.

3 16. Both the moon and Mercury have very large temperature variations between day and night. The main reason for this large variation is: (A) lack of atmosphere. (B) rocky composition. (C) distance from the sun. (D) small mass. 17. Which planet is most like Venus in size and mass? (A) Earth. (B) Mars. (C) Mercury. (D) Neptune. 18. Which of the following best describes the rotation of Venus? (A) slow and forward (prograde) (B) slow and backward (retrograde) (C) rapid and forward (prograde) (D) rapid and backward (retrograde) 19. Why does Venus appear featureless when viewed through a telescope? (A) it has a very thick cloud layer (B) it has permanent dust storms. (C) its atmosphere is so hot that shimmering distorts its image (D) it has an extremely smooth surface. 20. Why is the surface of Venus so hot? (A) Infrared radiation emitted by the surface can't escape into space. (B) Venus absorbs nearly all of the solar radiation that strikes it. (C) Frequent volcanic eruptions heat the lower atmosphere. (D) The surface is heated by radioactivity in surface rocks. 21. There seem to be no old impact craters on Venus. Why not? (A) Venus was formed much more recently than astronomers previously thought. (B) Venus's entire surface was flooded with lava a few hundred million years ago. (C) old impact craters have been wiped out by more recent impact craters. (D) plate tectonics destroys old craters on Venus. 22. By observing the orbits of the two satellites of Mars, we can determine Mars' (A) diameter. (B) temperature. (C) mass. (D) moisture content. 23. Some of the Martian channels originate in chaotic (jumbled) terrain. How were the chaotic terrain and the channels emerging from them probably produced? (A) melting of underground ice followed by the flow of water (B) small volcanic outbursts followed by the flow of lava (C) grazing impacts by interplanetary debris (D) Mars-quakes followed by landslides

4 24. In which of the following forms can water NOT exist on Mars today? (A) lakes (B) atmospheric ice crystals (C) underground ice deposits (D) atmospheric gas 25. We see impact craters on the slopes of large Martian volcanoes. What does that tell us about the volcanoes? (A) They are billions of years old (B) They attract infalling meteoroids (C) There have never been rivers on the volcano slopes (D) They produce lava that is laid down in very thin layers 26. During some seasons the barometric pressure on Mars drops steadily for months at a time. Why? (A) gas is escaping rapidly into space. (B) enormous storms are forming around low pressure regions. (C) tides cause the atmosphere to rise and fall. (D) the atmospheric gas is solidifying on one of the polar caps. 27. Why is Mars red? (A) solar UV radiation has damaged surface materials (B) it is covered by red colored lichens and mosses (C) red light penetrates the atmosphere better than blue light (D) its soil contains highly oxidized iron compounds 28. Which of the following is a characteristic of a Jovian planet? (A) Location in the inner solar system. (B) Diameter of at least 500,000 km. (C) Mean density of about 5 times that of water. (D) Atmosphere containing mostly hydrogen and helium. 29. What two chemical elements make up most of Jupiter's mass? (A) Oxygen and nitrogen. (B) Iron and silicon. (C) Hydrogen and helium. (D) Carbon and argon. 30. The variation between pole and equatorial rotation rates for a Jovian planet (A) is called differential rotation. (B) is evidence that the planet is fluid. (C) has never actually been observed. (D) both (A) and (B) above. 31. What is the conducting material that gives rise to Jupiter's magnetic field? (A) iron and nickel. (B) a salty water solution. (C) copper. (D) metallic hydrogen.

5 32. How do we know that the Red Spot of Jupiter is not a hurricane like storm? (A) Its winds are too gentle. (B) It rotates in the "wrong" direction. (C) No lightning has been detected within it. (D) It has been observed to cross the equator of Jupiter. 33. In which part of Saturn s rings do the ring particles take the least time for an orbit? (A) the innermost part of the rings. (B) the outermost part of the rings. (C) in Casssini s division. (D) all part take exactly the same time for an orbit. 34. What would happened to an asteroid that came within the Roche limit of a planet? (A) It would be ejected at twice the speed it originally had. (B) It would be destroyed by tides. (C) It would be captured and become a satellite. (D) It would be burned up in the atmosphere of the planet. 35. How did William Herschel know that Uranus is a planet and not a star? (A) it was too bright to be a star. (B) he saw it move among the stars from night to night. (C) all of the stars in that part of the sky had already been accounted for. (D) he could see cloud features on Uranus. 36. Which of the following planets sometimes has its poles pointed almost directly at the Sun? (A) Mars (B) Jupiter (C) Earth (D) Uranus 37. How was Neptune discovered? (A) by accident, while an astronomer was looking for comets (B) it passed in front of a bright star (C) by looking at a position predicted by calculations (D) this is a trick, it has been known since antiquity 38. What is unusual about the obits of Neptune and Pluto? (A) Pluto is sometimes nearer the sun than is Neptune (B) they occasionally have near collisions (C) their years have the same length (D) they are always on opposite sides of the sun from each other 39. The Pioneer and Voyager spacecraft were used to search for planets beyond Pluto. What property of such planets was searched for by the spacecraft? (A) Their gravitational attractions, which would cause slight deflections in the spacecrafts' paths (B) Visible light reflected by them (C) Radio emission from them (D) Eclipses of the Sun by them

6 40. Which planet s satellites closely resemble asteroids? (A) Mars (B) Venus (C) Uranus (D) Pluto 41. What are the most notable surface features of Jupiter s satellite Io? (A) volcanoes. (B) grooved ridge systems (C) regions with high impact crater densities (D) smooth regions produced by flows of liquid water 42. Why are the inner Galilean satellites denser than the outer ones? (A) the outer ones contain more icy material. (B) the inner ones contain more iron. (C) the inner ones are larger. (D) the outer ones are made mainly of gas. 43. The heat that keeps the interior of Io molten is due to (A) tides (B) radioactive materials (C) frequent meteoroid impacts (D) a large greenhouse effect 44. What is remarkable about Uranus s satellite, Miranda? (A) It has several distinct types of surface terrain. (B) It is more massive than any other satellite of Uranus. (C) It reflects essentially all the sunlight that strikes it. (D) It has a satellite of its own. 45. Most of the asteroids have orbits that lie between the orbits of (A) Mars and Jupiter (B) Venus and the Earth (C) the Earth and Mars (D) Jupiter and Saturn 46. Most meteorite solidification ages are (A) older than 10 billion years. (B) about 4.6 billion years. (C) about 4.6 million years. (D) about 4.6 thousand years. 47.Which of the following characterizes the composition of a comet's nucleus? (A) dirty snowball. (B) muddy rock. (C) thin gas. (D) rain drop.

7 48. When does a comet have the longest tail and largest coma? (A) when it is moving most slowly (B) when it crosses the ecliptic (C) when it is nearest the Sun (D) when it is 1 AU from the Sun 49. Impact craters (A) appear to have never been produced on the Earth. (B) are observed only on the Moon (C) appear to be a widespread solar system phenomenon. (D) were caused by volcanic caldera. 50. The particles which produce meteor showers come from (A) impacts of meteoroids with the moon. (B) dead comets. (C) collisions of asteroids with each other. (D) interstellar space.