e planets a. and the moon orbiting the sun. b. orbiting the sun and the moon orbiting Earth. c. and the moon and sun orbiting Earth. d. orbiting the sun and the sun orbiting Earth. ____ 22. What does the heliocentric model of the solar system state? a. Earth and the other planets orbit the sun. b. All of the planets and the sun orbit Earth. c. Only the moon and Earth orbit the sun. d. The planets orbit the Earth, which orbits the sun. ____ 23. Who was the first person to propose a heliocentric model of the universe? a. Archimedes c. Ptolemy b. Aristarchus d. Galileo ____ 24. After the Middle Ages, the astronomer who changed the model of the solar system by placing the sun at its center was a. Galileo. c. Copernicus. b. Ptolemy. d. Kepler. ____ 25. Which astronomer discovered that the planets orbit the sun in oval-shaped paths called ellipses? a. Kepler c. Galileo b. Brahe d. Archimedes ____ 26. Galileo's most important contribution to astronomy was his a. discovery of evidence that the sun is the center of the solar system. b. set of calculations of the size of each of the planets. c. discovery of the planet Mars. d. description of the behavior of moving objects. ____ 27. Isaac Newton was the first person to formulate and test the law of a. universal gravitation. c. orbital velocity. b. acceleration. d. universal mass. ____ 28. The spinning of Earth on its axis is called a. revolution. c. rotation. b. precession. d. perihelion. ____ 29. What is Earth's motion in its path around the sun called? a. aphelion c. precession b. rotation d. revolution ____ 30. What is precession? a. the tilt of Earth's axis in relation to the ecliptic b. the rotation of Earth as it moves around the sun c. the faster orbital velocity of the planet at perihelion d. the slow change in the direction in which Earth's axis tilts ____ 31. What causes the moon's phases? a. the rotation of the moon on its axis b. Earth's tilt on its axis as it revolves around the sun c. changes in how much of the sunlit side of the moon faces Earth. d. the position of the moon each month in relation to the North Star ____ 32. The cycle of the moon through its phases, or the synodic month, is a. 21 days long. c. 29 1/2 days long. b. 27 1/3 days long. d. 30 days long. ____ 33. A solar eclipse occurs when a. Earth casts a dark shadow on the moon. b. the moon casts a dark shadow on Earth. c. Earth casts a dark shadow on the sun. d. the sun casts a dark shadow on the moon. ____ 34. During a total lunar eclipse, the moon a. moves into Earth's umbra. c. moves into Earth's penumbra. b. moves into the sun's umbra. d. moves outside Earth's shadow. ____ 36. What is the soil-like layer on the moon's surface called? a. maria c. basalt b. regolith d. magma ____ 37. Long valleys or trenches associated with maria are a. rays. c. ejecta. b. craters. d. rilles. ____ 38. Which of the following is NOT present on the moon? a. light c. atmosphere b. gravity d. heat ____ 39. The most widely accepted model for the origin of the moon involves a. the formation of the moon from dust and gas when Earth formed. b. a large body hitting Earth and ejecting debris that became the moon. c. the capture of the moon from Mars by Earth. d. a large body hitting Mars and splitting off debris that became the moon. ____ 40. Which of the following lunar features is the oldest? a. surface regolith c. craters with rays b. highlands d. maria basins ____ 41. Which of the following is NOT considered a terrestrial planet? a. Mars c. Neptune b. Venus d. Mercury ____ 42. The largest of the terrestrial planets is a. Jupiter. c. Mars. b. Earth. d. Uranus. ____ 43. The densities of the Jovian planets are a. not more than about 0.5 times the density of water. b. not more than about 1.5 times the density of water. c. from 3.9 to 5.5 times the density of water. d. more than 5.5 times the density of water. ____ 44. According to scientists, the solar system formed from a. colliding planetesimals. c. colliding nebulae. b. rotating stars. d. a rotating disk of dust and gases. ____ 45. Which of the following is one difference between the way terrestrial planets and Jovian planets formed? a. The terrestrial planets formed only from bits of ice. b. The Jovian planets formed only from bits of ice. c. The terrestrial planets formed only from metals and silicate minerals. d. The Jovian planets formed only from metals and silicate minerals. ____ 46. How does the diameter of the terrestrial and Jovian planets compare? a. The diameters of the Jovian planets are much larger. b. All but one of the terrestrial planets have diameters about equal to the diameters of the Jovian planets. c. The diameters of the terrestrial planets are much larger. d. All but one of the Jovian planets have diameters about equal to the diameters of the terrestrial planets. ____ 47. The fact that Mercury has no atmosphere is evidence that it a. reflects almost all of the sunlight that strikes it. b. is composed almost entirely of gases. c. is much farther from the sun than it appears. d. reflects a small percentage of the sunlight that strikes it. ____ 48. One reason that life as we know it is unlikely to exist on Venus is because a. the surface temperature is too high. b. the surface temperature is too low. c. the surface has too much ice covering it. d. there is no atmosphere. ____ 49. When viewed from Earth, Mars appears to change colors. This most likely happens because a. gases in the dense Martian atmosphere are constantly changing. b. volcanic activity produces thick gas clouds. c. dust storms lasting for weeks cause the atmosphere to change color. d. active volcanoes on the Mars surface intermittently flood the surface with lava. ____ 50. What is the mass of Jupiter? a. times the mass of Earth b. twice the mass of all the terrestrial planets c. about half the mass of all the Jovian planets d. times the mass of all the other planets and their moons ____ 51. Which of the Jovian planets have rings? a. only Saturn and Jupiter c. only Saturn and Neptune b. Saturn, Jupiter, Uranus, and Neptune d. only Saturn, Jupiter, and Uranus ____ 52. Which planet has the lowest surface temperature of any planet and an atmosphere comprised mostly of nitrogen? a. Jupiter c. Neptune b. Saturn d. Uranus ____ 53. Which planet has an axis of rotation parallel with the plane of its orbit? a. Jupiter c. Neptune b. Saturn d. Uranus ____ 54. Most asteroids lie between the orbits of a. Jupiter and Saturn. c. Jupiter and Neptune. b. Mars and Jupiter. d. Mars and Earth. ____ 55. Which of the following is true about asteroids? a. Asteroids rarely pass close to Earth. b. Asteroids never actually collide with planetary bodies. c. Recent impact craters on the moon were likely caused by asteroids. d. Most asteroids are no larger than a grain of sand. ____ 56. Which of the following is true about comets? a. The orbits of comets do not take them past the Jovian planets. b. Comets are held together by frozen gases. c. All comets have long tails made of vaporizing gases. d. The Oort cloud of comets is found between Neptune and Pluto. ____ 57. The Kuiper Belt is a region beyond Neptune containing a. comets with short orbit periods. c. a dense collection of meteoroids. b. meteors smaller than 1 km across. d. comets with unusually large nuclei. ____ 58. The nucleus of Halley's comet is approximately a. 1 m wide. c. 16 km by 8 km. b. 1 km wide. d. 100 km wide. ____ 59. Scientists have been able to estimate the age of our solar system by dating a. comets. c. meteors. b. asteroids. d. meteorites. ____ 60. Which of the following is NOT a source of meteoroids? a. rocky chunks from neighboring solar systems b. leftover interplanetary debris c. material from the asteroid belt d. the solid remains of comets ____ 62. Which of the following types of visible light has the longest wavelength? a. red c. violet b. green d. blue ____ 63. A star's spectrum can tell astronomers a. how big the star is. c. the age of the star. b. the star's chemical composition. d. how far away the star is from Earth. ____ 65. What does the use of the Doppler effect tell astronomers about a star? a. a star's exact velocity as it moves in the galaxy b. the chemical composition of the star c. its diameter compared to that of the sun d. whether a star is moving toward or away from Earth ____ 67. What does a refracting telescope use to produce an image? a. a mirror c. a prism b. a spectroscope d. a lens ____ 69. What does a reflecting telescope use to produce an image? a. a mirror c. a prism b. a spectroscope d. a lens ____ 70. Which of the following statements is NOT true of most large optical telescopes? a. They are refracting telescopes. b. They have greater light-gathering power. c. They have greater resolving power. d. They are reflecting telescopes. ____ 71. What do radio telescopes use to gather and focus radio waves? a. a very large mirror c. a huge dish b. a set of glass lenses d. a tall rotating tower ____ 72. Radio telescopes measure the galaxy's distribution of a. dust ejected from asteroid impacts on other planets. b. photons from the sun. c. hydrogen from which stars are formed. d. X-rays given off by black holes. ____ 73. What advantage do space telescopes have over Earth-based telescopes? a. They are much cheaper to build. b. They do not have interference from the atmosphere. c. They do not need lenses or mirrors to gather light. d. The weaker gravity around them makes images sharper. ____ 75. The visible surface of the sun is its a. corona. c. photosphere. b. chromosphere. d. prominence. ____ 76. Streams of electrons and protons that shoot out from the sun's corona are the solar a. prominences. c. chromosphere. b. channels. d. wind. ____ 77. Sunspots appear as darker areas on the sun's surface because they are a. hotter than the rest of the surface. c. solid areas on the sun's surface. b. holes in the sun's surface. d. cooler than the rest of the surface. ____ 78. Which of the following is an effect of solar flares on Earth? a. bombards Earth with radio waves c. makes the climate warmer b. creates auroras d. causes the magnetic poles to reverse ____ 80. The sun can continue to exist in its present stable state for about another a. 1 billion years. c. 10 billion years. b. 5.5 billion years. d. 15.5 billion years. ____ 81. What color will a star be with a surface temperature of 5000-6000 K? a. blue c. yellow b. red d. white ____ 82. The mass of a star can be determined by studying a. the wavelength of light emitted by the star. b. the color of the star. c. the distance between the star and Earth. d. binary star systems. ____ 83. Which of the following is true about using parallax to measure distance to stars? a. The closer the star, the smaller is the parallax angle. b. The closer the star, the larger is the parallax angle. c. The larger the star, the smaller is the parallax angle. d. The larger the star, the larger is the parallax angle. ____ 84. Approximately how long is a light-year? a. 9.5 billion km c. 9.5 trillion km b. 95 billion km d. 95 trillion km ____ 85. Which of the following is NOT a factor that affects the apparent brightness of a star as seen from Earth? a. how old the star is c. how hot the star is b. how big the star is d. how far away the star is ____ 86. Star A is farther away from Earth than star B. Both stars have the same absolute magnitude. Which of the following is true about their apparent magnitude? a. Both stars will have the same apparent magnitude. b. Star A will have a greater apparent magnitude. c. Star B will have a greater apparent magnitude. d. The apparent magnitude of either star will not depend on its position. ____ 87. A Hertzsprung-Russell diagram is used to show the relationship between a. absolute magnitude and apparent magnitude. b. temperature and absolute magnitude. c. parallax and temperature. d. apparent magnitude and parallax. ____ 88. About 90 percent of the stars on the Hertzsprung-Russell diagram are a. supergiants. c. white dwarfs. b. main-sequence stars. d. red giants. ____ 89. Before a star is born, the matter that will become the star exists as a a. bright explosive supernova. c. black hole. b. red giant. d. cool, dark nebula. ____ 90. A star is thought to be born when a. a protostar reaches a temperature high enough for nuclear fusion to begin. b. a red giant collapses on itself and becomes a black hole. c. pressure within a protostar becomes so great that a supernova occurs. d. increasing heat within a supergiant causes gravity to be greater than pressure. ____ 91. Into which of the following life cycle stages will the sun enter next? a. white dwarf stage c. planetary nebula stage b. red giant stage d. black dwarf stage ____ 92. Which of the following will be the final stage in the sun's life cycle? a. nova stage c. planetary nebula stage b. red giant stage d. black dwarf stage ____ 93. All stars, regardless of their size, eventually a. turn into a black dwarf. c. run out of fuel and collapse. b. produce a supernova explosion. d. collapse into a white dwarf. ____ 94. What remains after a low-mass or medium-mass star dies? a. a nebula c. a black hole b. a white dwarf d. a neutron star ____ 95. At its nucleus, the Milky Way galaxy is about 100,000 lightyears wide and about a. 1,000 light-years thick. c. 100,000 light-years thick. b. 10,000 light-years thick. d. 1,000,000 light-years thick. ____ 96. According to information received from radio telescopes, where is our sun positioned in the Milky Way? a. at the exact center of the galactic nucleus c. at the tip of one of the spirals b. just outside the galactic nucleus d. within one of the spirals ____ 97. About 60 percent of all known galaxies are classified as a. spiral galaxies. c. irregular galaxies. b. elliptical galaxies. d. galactic clusters. ____ 98. Scientists know the universe is expanding because of the a. red shift of distant galaxies. c. blue shift of distant galaxies. b. red shift of the brightest galaxies. d. blue shift of the brightest galaxies. ____ 99. According to the big bang theory, the entire universe began as a a. supernova explosion. c. dense, hot, supermassive ball. b. cool, dark expansive nebula. d. scattered band of space dust. ____ 100. Which of the following is supportive evidence of the big bang theory? a. pulsars b. cosmic microwave background radiation c. galactic clusters d. the different shapes of galaxies