Full Session Course Dr Michael Burton GENS4001 Astronomy Sample Test Questions Name: _______________________ Instructions: Sample test questions are given below. Select the correct answers from the 4 options given. For the in-session test roughly 10 questions will be set on each of the three topics (i) Solar System, (ii) Stars and (iii) Galaxies and Cosmology. _____________________________________________ 1. The most likely mechanism for the solar system is that a. the Sun and planets slowly condensed to their present form from a gas and dust cloud. b. planets were spun out of the Sun as smaller gas clouds and subsequently condensed. c. the Sun captured the planets as they drifted through space. d. the solar system was once a galaxy, from which the Sun and planets are the remnants, after evolution. 2. The most probable time sequence for the formation of the solar system was that a. the planets formed first out of a cold nebula of gas and dust, followed by the Sun, which formed when the gas had become much hotter. b. the Sun formed initially, and the planets and major moons were captured much later as they drifted by the Sun. c. the Sun contracted first as a gas ball, and the planets and moons formed shortly afterwards by accretion and condensation. d. the Sun formed first, the planets were spun off from the Sun, and the moons in turn were spun off from the planets. 3. The manner in which the terrestrial planets formed was a. accretion of planetesimals to form a core, followed by gravitational capture of gas from the solar nebula. b. accretion of solid planetesimals containing mostly rocky material. c. gravitational condensation of hydrogen, helium, and dust in eddies or vortices in the solar nebula. d. gravitational condensation of gas followed by capture of solid planetesimals. 4. Most of the planets orbit the Sun on or close to a. the ecliptic plane. b. the plane of the Milky Way Galaxy. c. the equatorial plane. d. the plane containing both north and south celestial poles and the zenith at Greenwich, England. 5. Comets are typically a. chunks of ice that begin to vaporize if they pass close to the Sun. b. chunks of rock typically a few tens of kilometers in diameter. c. gaseous bodies from which some of the gas is pushed out by the Sun to form a long tail. d. slushy mixtures of liquid and ice. 6. What is the photosphere of the Sun? a. The visible "surface" of the Sun. b. The middle layer of the Sun's atmosphere. c. The core of the Sun, where nuclear energy is generated. d. The region of convecting gases below the visible surface of the Sun. 7. Where is the chromosphere on the Sun? a. It is the layer above the visible surface of the Sun. b. It is the visible surface of the Sun. c. It is the layer below the visible surface of the Sun. d. It is the outermost part of the Sun's atmosphere. 8. The temperature of the corona of the Sun a. is very cool, since it is furthest from the heat source. b. is very hot, about 106 K. c. is about the same as that of the photosphere, 5,800 K. d. is about twice as hot as the photosphere, 12,000 K. 9. What is the average length of time from one sunspot maximum to the next? a. 11 years b. 22 years c. 4 1/2 years d. 7 years 10. What is the energy source for the Sun? a. Thermonuclear fusion in the core. b. Heat released by gravitational contraction. c. Primordial heat left over from when the Sun first formed. d. Radioactivity. 11. Which is the most abundant gas in the Earth's atmosphere? a. nitrogen b. oxygen c. carbon dioxide d. hydrogen 12. In which layer of the Earth's atmosphere does all of the weather occur? a. the troposphere b. the thermosphere c. the stratosphere d. the mesosphere 13. Which ONE of the following processes was important for melting the entire Earth about 4.6 billion years ago? a. Radioactivity, or the spontaneous breaking apart of heavier nuclei into lighter ones. b. Nuclear fusion, or the combining of lighter nuclei to form heavier ones. c. Tidal heating of the Earth due to the combined gravitational pulls of the Sun and the Moon. d. Heat released by the condensation of water vapor into liquid water, to form the oceans. 14. The internal structure of the Earth is a. a large, solid iron core surrounded by a thick, flexible mantle of rock. b. a large core of iron, partly solid and partly molten, surrounded by a thick, flexible mantle of rock. c. a core of rock and iron, surrounded by a mantle of liquid hydrogen. d. a core of solid rock extensively enriched in iron, surrounded by a solid mantle of pure rock. 15. Most of the craters on the Moon are thought to have been caused by a. the continuous bombardment throughout the Moon's life, including the present and recent past, by large and small asteroids. b. the collapse of volcanic domes, leaving central peaks in the craters. c. volcanic activity, leaving behind volcano craters similar to those on Earth. d. the intense bombardment by large and small bodies over some specific early period in the Moon's history. 16. Which of the following features were NOT found on Mars when spacecraft finally visited the planet? a. Deep, winding canyons b. Craters c. Straight canals d. Extinct volcanoes 17. The "snow" that occasionally falls on Mars and covers the bottoms of craters is most probably made of a. carbon dioxide ice. b. water ice. c. frozen sulfuric acid droplets. d. very fine white dust, disturbed occasionally by fierce wind storms. 18. The major volcanoes on Mars have formed a. over individual stationary "hot-spots" in the underlying molten mantle. b. on long, interconnected ridges where magma, rising from the mantle, is pushing the crust apart. c. in mountain belts where the planet's surface is being stressed as it is bent and subducted back into the mantle. d. where shrinkage of the crust during cooling early in the planet's history has wrinkled the surface. 19. What significant evidence is there for the idea that large quantities of water once flowed on Mars? a. There is a network of relatively straight canals linking polar and equatorial regions. b. Deep, winding canyons and flood plains were seen in Mariner spacecraft photographs. c. Frozen but dust-covered lakes inside ancient craters were found by orbiting instruments. d. Clouds and frost were seen to form above and around the Viking spacecraft. 20. Which of the following would NOT be a weather report from Mars, in view of the present atmospheric conditions on that planet? a. Dry-ice snow. b. Rain, becoming light rain by noon. c. Clear and cold. d. Dry and windy with blowing dust. 21. What are the characteristic features on the visible surface of Jupiter? a. Light and dark bands of clouds parallel to the equator. b. Large volcanoes and a long, deep rift valley. c. A greenish, almost featureless cloud layer. d. A bluish tint with high, white clouds and dark storms. 22. What is the dominant circulation pattern in Jupiter's atmosphere (i.e., at the visible "surface")? a. Alternating bands of eastward and westward flow parallel to the equator, with light and dark ovals between these flows. b. Isolated storms and turbulent swirls, with little overall flow pattern in any particular direction. c. Air rising at the equator, flowing north and south towards the poles, then sinking and returning to the equator at a lower level. d. Uniform eastward flow of the entire atmosphere, with occasional dark storms and turbulent swirls. 23. What is the basic structure of the planet Jupiter? a. Rocky core, liquid hydrogen mantle, gaseous atmosphere. b. Rocky core, liquid methane and water mantle, gaseous atmosphere. c. Entirely liquid hydrogen, except for a thin, gaseous atmosphere. d. Rocky core, frozen water mantle, thin methane atmosphere. 24. What causes the extensive volcanic activity observed on Jupiter's satellite, Io? a. Tidal stresses from Jupiter. b. Heat released by radioactivity in Io's core and mantle. c. "Primordial" heat remaining from when Io first formed. d. Frictional heating by mantle convection and crustal tectonics. 25. What physical mechanism most probably caused the very long cracks and streaks that crisscross the surface of Europa, the moon of Jupiter? a. Volcanic eruptions caused lava flows that then froze in place. b. They are frozen rivers that, in warmer times, were flowing across the moon's surface. c. Tidal flexing by Jupiter cracked the surface, and subsurface fluids gushed upwards and froze. d. They are the tops of gigantic greenhouses built by inhabitants of Europa to protect their cucumber crops. 26. How far away is the nearest star beyond the Sun? a. About 4 light years away. b. Between 1 and 2 light years away. c. About 1/4 light year away. d. About 1/10 light year away. 27. Stellar parallax is a. the circular or elliptical motion of a star in a binary system, as the two stars orbit around each other. b. the apparent change in the distance to a star if its light is dimmed by passing through interstellar clouds. c. the apparent shift that we see in the position of a nearby star as we orbit the Sun. d. the difference between the apparent magnitude and the absolute magnitude of a star. 28. The luminosity of a star is a. another name for its color or surface temperature. b. its brightness as seen by people on Earth. c. its brightness if it were to be at a distance of 10 parsecs (32.6 light-years) from Earth. d. its total energy output into all space, over all wavelengths. 29. If two stars in the sky are not hidden by gas or dust clouds, and have the same apparent brightness in our sky, then we know that a. they may be at different distances, in which case the farther one must have the greater luminosity. b. they are necessarily at the same distance away from us. c. they have the same temperature. d. they may be at different distances, in which case the nearer one must have the greater luminosity. 30. Using telescopes on the Earth, to approximately what distance can parallax be used to measure the distances to stars with reasonable accuracy? a. 500 pc b. 10 pc c. 2,000 pc d. 100 pc 31. The technique called photometry in stellar astronomy is the measurement of a. the intensity of light from stars through several limited-bandpass filters from which surface temperature, variability, luminosity, etc. of stars can be determined. b. the relative absorption of light by different atoms and molecules in high resolution spectra of starlight, from which stellar temperatures can be estimated. c. the precise positions and relative motions of stars in the galaxy, from which galactic structure and overall rotation can be determined. d. the arrival times of photons from variable and pulsating stars, in order to determine accurately the pulsation or rotation periods of these stars. 32. A star in the lower left part of the Hertzsprung-Russell diagram, compared to a star in the middle of the diagram, is a. smaller. b. cooler. c. brighter. d. larger. 33. An eclipsing binary system is a. two mutually orbiting and gravitationally-bound stars that are close enough to be resolved when viewed from Earth. b. a star that is periodically eclipsed by the Moon. c. two stars that periodically eclipse each other, as seen from Earth. d. two stars in which spectral lines move back and forth periodically because of Doppler shift, indicating mutually orbiting stars. 34. The Hertzsprung-Russell diagram is a plot of a. apparent brightness against distance for stars near to the Sun. b. apparent brightness against intrinsic brightness of a group of stars. c. luminosity against mass of a group of stars. d. absolute magnitude (or intrinsic brightness) against temperature of a group of stars 35. The color index of a star, the difference between the apparent magnitudes B and V at two different colors, blue and visual, is directly related to which stellar property? a. surface temperature b. luminosity c. radius d. distance from Earth 36. The space between stars is known to contain a. variable amounts of gas but no dust, which only forms in planetary systems near stars. b. a perfect vacuum. c. dust and gas, both atomic and molecular. d. large quantities of dust that absorb light, but no gas, either atomic or molecular. 37. How do massive stars normally end their lives? a. They explode. b. They gradually shrink to the size of the Earth. c. We don't know, since their lifetimes are longer than the age of the universe. d. They collapse and become black holes. 38. The characteristics of an open cluster of stars are a. many thousand members, of different ages. b. a few hundred members, often very young and still embedded in the gas and dust from which they were formed. c. hundreds of thousands of members, all very old, and no or very little interstellar gas and dust. d. a few dozen members, the remnant of a globular cluster of stars from which most of the members have escaped. 39. Which part of the Hertzsprung-Russell diagram is occupied by protostars? a. to the right of the main sequence b. to the left of the main sequence c. a band running from upper left to lower right d. a band running from upper right to lower left 40. What causes the characteristic blue color of a reflection nebula? a. Scattering of starlight from dust grains in the nebula. b. Electrons dropping from n = 2 to n = 1 in hydrogen atoms. c. Electrons dropping from n = 3 to n = 2 in hydrogen atoms. d. Thermal (blackbody) radiation. 41. Which of the following objects is NOT an end-point of a star's evolutionary life? a. supernova b. red giant c. neutron star d. black hole 42. Which of the following important components does a planetary nebula contribute to the interstellar medium? a. Rotational motion from the original star, which serves to concentrate interstellar matter into new stars and planetary systems. b. New hydrogen nuclei, replenishing those that are lost when stars form. c. UV light that photo-ionizes hydrogen. This hydrogen, upon recombination, produces the red Balmer-a light by which we see interstellar emission nebulae. d. The nuclei of heavy elements, major components of planets such as our own. 43. Our Sun will end its life by becoming a. a white dwarf. b. a pulsar. c. a black hole. d. a molecular cloud. 44. From observations of supernova explosions in distant galaxies, it is predicted that there should be about 5 supernovae per century in our galaxy, whereas we have seen only about 1 every 300 years from Earth. Why is this? a. Most supernovae occur within the Milky Way, which can be seen only from the southern hemisphere where there have been very few observers until recently. b. Most supernovae occur in the galactic plane where interstellar dust will have hidden them from our view. c. The majority of stars in our galaxy are old, well beyond the supernova stages of evolution. d. The majority of supernovae produce no visible light, only radio and x-ray radiation, which we have only been able to observe for the past 3 decades. 45. After the material in the core of a massive star has been converted to iron by thermonuclear reactions, further energy can be released to heat the core ONLY by a. thermonuclear fusion of iron into heavier elements. b. the absorption of neutrinos. c. nuclear fission or splitting of nuclei. d. gravitational contraction. 46. Why are black holes named black holes? a. No light or any other electromagnetic radiation can escape from inside them. b. They emit a perfect blackbody spectrum. c. Their only spectral lines are in the radio and infrared. d. All of their electromagnetic radiation is gravitationally redshifted to the infrared, leaving no light in the optical region. 47. What is the likely final fate of a star whose mass is 15 solar masses after it has finished its nuclear burning phases? a. It will immediately split into two and become a binary star system. b. It will condense to the point where it is composed completely of neutrons, the degeneracy of which will prevent further shrinkage. c. The degeneracy of the electrons within the star will prevent collapse below the diameter of a white dwarf. d. It will collapse and become a black hole. 48. Light traveling away from the surface of a neutron star becomes strongly redshifted. What name is given to this effect? a. gravitational redshift b. cosmological redshift c. Doppler shift d. Zeeman effect 49. What is a singularity? a. a point of infinite density b. any point at the Schwarzschild radius of a black hole c. a tunnel into another universe d. a particle-antiparticle pair 50. If you were to enter the event horizon of a black hole, a. you could avoid the singularity by going into orbit around it, but you could never move outward again from any particular orbit. b. there would be nothing you could do to prevent yourself from falling directly into the singularity at the center. c. you could, with a powerful rocket, move outward within the black hole (thereby avoiding the singularity until your fuel ran out), but you could never escape back out through the event horizon. d. you could escape again provided the black hole is spinning. 51. The Milky Way Galaxy a. is unique in the universe in showing definite spiral structure. b. is one of many billions of galaxies in the universe. c. contains the whole universe; everything observable is within its volume. d. is one of only a few spiral galaxies, most other galaxies in the universe are amorphous collections of stars shaped like ellipsoids. 52. Cepheid variable stars are invaluable in astronomy because of the close relationship between a. the peak wavelength of their spectrum and their surface temperatures. b. the red shift of their spectrum and their distance from the Sun. c. their apparent magnitude and their pulsation period. d. their luminosity, or absolute magnitude, and their pulsation period. 53. What is it that makes the study of the structure of our own Galaxy more difficult than that of much more distant spiral galaxies? a. Most of our Galaxy is hidden behind dense gas and dust clouds in the galactic plane. b. Our star is within the Galaxy and its motion confuses the interpretation of the motion of other parts of the Galaxy. c. Our galaxy is too close, such that photographs or images cannot be taken of the whole Galaxy at any one time. d. The galactic center is visible only from the southern hemisphere where, until recently, no major telescopes were available for the study of galactic structure. 54. Galaxies throughout the universe appear to be distributed a. uniformly throughout space. b. in groups and surfaces surrounding vast voids, much like the surfaces of giant bubbles. c. around a single point in space, the presumed location of the original Big Bang which created the universe. d. mostly in a single spherical shell surrounding a void in space, presumed to have been caused by a vast explosion at the time of the Big Bang. 55. Cepheid-stars are useful to astronomers as indicators of a. distance, particularly to nearby galaxies. b. the existence of black holes. c. stars with very high speed motion. d. white dwarf star behavior. 56. The factor that misled Herschel into concluding that the stars of the Milky Way were distributed with the Sun at the center of the Galaxy was a. that most of the "stars" that he measured were in fact distant galaxies distributed uniformly around the Sun. b. interstellar dust, which obscured the more distant stars and thereby localized his observations. c. gravitational bending of light by the mass of the Galaxy, distorting the relative positions of the stars. d. hot hydrogen gas in the Galaxy, its emission hiding the more distant stars. 57. Where in space would you look for a globular cluster? a. In the asteroid belt. b. In the Milky Way disk, moving in a circular orbit around the galactic center. c. Only in elliptical galaxies, since they are composed of old stars and do not exist in young systems like spiral galaxies. d. In the Milky Way galactic halo, orbiting the galactic center in a long elliptical orbit around the galactic center. 58. The major advantages of the 21 cm radio emission from hydrogen gas for investigating the spiral structure of our galaxy are a. that radio waves easily penetrate the Milky Way dust and gas and it is a very narrow line emission, thus its Doppler shift can be used to measure gas motions. b. that this emission can easily penetrate the Milky Way gas and dust and comes only from hot gas, and hence can be used to map the distribution of hot hydrogen gas. c. that it is relatively easily absorbed by hydrogen gas in the Milky Way, so that measurements are not confused by emission of this radiation from other galaxies beyond the Milky Way. It originates only from cold hydrogen gas, and can be used to map this important component. d. that Doppler shift of this narrow-wavelength line emission is caused by the temperature of the hot hydrogen gas and therefore can be used to measure the distribution and temperature of this important component of the Milky Way. 59. The time taken for the Sun to orbit the galactic center once in its motion in the Galaxy is a. 28,000 years. b. 2.3 million years. c. about a half million years. d. 230 million years. 60. The center of our Milky Way Galaxy can be observed most easily at which of the following electromagnetic wavelengths? a. high-energy gamma rays b. visible light c. infrared and radio waves d. ultraviolet radiation 61. What is the basic shape of a spiral galaxy? a. A round, flat disk with long lanes of stars that curve outwards from a round, nuclear region of uniform brightness. b. A round, flat disk with long lanes of stars that curve outwards right from the center of the galaxy. c. A round, thin disk of uniform brightness with its edges bent up and down into a spiral shape. d. Approximately spherical with long lanes of dark dust clouds curving through it in a spiral pattern. 62. The typical diameter of a spiral galaxy is about a. 1 light-year. b. 100 light-years. c. 107 light-years. d. 105 light-years. 63. Which one of the following statements does NOT correctly describe a typical elliptical galaxy? a. They have a central bulge and a disk, but no spiral arms. b. They have a smooth light distribution with various degrees of flattening from a circular shape. c. They contain primarily low-mass stars. d. They cover the entire range of masses from the smallest to the biggest galaxies in the universe. 64. How are galaxies spread through the universe? a. They are grouped into clusters that in turn are grouped into clusters of clusters (superclusters). b. They are grouped into clusters that are spread more-or-less evenly throughout the universe. c. Galaxies are spread more-or-less evenly throughout the universe. d. Galaxies are densest near the Milky Way Galaxy and become less and less numerous the further we look out into the universe. 65. What would happen if the Andromeda galaxy (a spiral about the same size as ours) collided with our own Milky Way Galaxy? a. The two galaxies would pass through each other, with the stars sailing past each other unharmed but the interstellar gas and dust clouds would collide. b. The two galaxies would shatter or even explode, essentially destroying their stars and any life forms that there may have been (including us). c. All of the gas and dust clouds and a great many of the stars would collide with each other, stopping both galaxies and creating a galactic merger. d. The two galaxies would pass through each other almost unchanged, with essentially no interactions at all. 66. The observed characteristics of a quasar are a. starlike image, extremely blue-shifted spectrum, often an intense radio emitter. b. starlike image, spectrum highly red-shifted, often an intense radio emitter. c. diffuse circular image, no red shift of the spectrum, often a very bright radio source. d. starlike image, with a highly variable Doppler spectrum that shifts from red to blue, and often a very bright radio source. 67. Quasars all appear to be a. moving towards us at high speeds, as high as 90% of the speed of light. b. moving across our line of sight at very high speeds, as seen from time-lapse photographs. c. moving away from us at very high speeds, at up to 90% of the speed of light. d. extremely massive objects in our galaxy, their intense surface gravity having red-shifted their spectra. 68. The highest recession velocities that have recently been detected for quasars is a. about one-quarter of the speed of light. b. almost half the speed of light. c. 70-80% of the speed of light. d. more than 90% of the speed of light. 69. Which observations of the radiation from quasars indicate that they are physically very small objects compared to galaxies? a. The very high redshift of their light. b. The rapid fluctuations in output, often in less than one day. c. Their starlike appearance on photographs, showing no structure. d. Their emission mostly being in the infrared and radio range. 70. What appears to be the central energy-generating system or "engine" that is producing prodigious amounts of energy in the centers of galaxies, active galaxies and quasars? a. There is no central "engine" in these sources. Their high gravity has focused radiation from many sources beyond them by gravitational lensing and they thus appear to be very bright. b. A supermassive black hole, where matter is compressed upon falling into the hole and heated to extremely high temperatures. c. A very rapidly rotating core of matter, where friction between it and the surrounding matter causes tremendous heat and energy output. d. A steady series of supernova explosions, the late evolutionary stages of massive stars. 71. Which scientist discovered that the equations he had derived predicted an expanding universe, then modified his equations to eliminate this expansion? a. Albert Einstein b. Edwin Hubble c. Stephen Hawking d. Isaac Newton 72. In relation to the universe, what does "isotropy" mean? a. The expansion is the same in all directions. b. The speed of expansion is the same at all distances. c. The speed of expansion at any given distance is the same at all times. d. The universe is the same everywhere, neither expanding nor contracting. 73. Where are we? a. Somewhere in an expanding universe, but not in any special part of it. b. At the exact center of an expanding universe, as shown by the universal expansion away from us in all directions. c. Near the edge of an expanding universe, as shown by the microwave radiation coming to us from the edge. d. Near, although probably not right at, the center of the universe, as shown by the fact that the edge is so far away. 74. Which one of the following statements is a correct description of the expansion of the universe? a. Spacetime is something real, with galaxies inside it; as spacetime expands, the galaxies (or superclusters of galaxies) are carried along by the expansion. b. Space is a vacuum, which is really nothing at all; the galaxies (or superclusters of galaxies) are hurtling outwards through this nothingness. c. Space is a vacuum, but the vacuum has real properties; as galaxies (or superclusters of galaxies) hurtle outwards, the expansion is gradually slowing down by the resistance of space to the passage of the galaxies. d. Spacetime is static, but exerts an outwards pressure on the galaxies in it; this pressure is accelerating the galaxies (or superclusters of galaxies) outwards through spacetime and away from each other. 75. Which single observation is perhaps the strongest argument against the steady-state model of the universe, and for the Big Bang model? a. The universe is bathed in a sea of microwaves coming from the edge of the visible universe. b. We have not observed matter being created from nothing in the space around us. c. The universe is expanding. d. The number of supporters of the steady-state model is less than the number of supporters of the Big Bang model.