Astro Final (Sample Test) 2024-2025. Questions and Correct, Verified Answers. Graded A+, Exams of Astronomy

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Astro Final (Sample Test) 2024-2025.

Questions and Correct, Verified Answers.

Graded A+

1. If a planet is seeing its Moon in the New Phase right now, in what phase would the planet appear to be when viewed from its Moon? a) Third Quarter Planet b) Full Planet c) New Planet d) You can't see the planet from its Moon e) First Quarter Planet - ANSb) full planet
2. What is the reason for the seasons on Earth? a) Earth is cloest to the Sun in July, farthest from the Sun in January b) Earth is tilted with respect to the Sun by about 23.5 degrees c) Earth orbits the Sun more slowly in winter, faster in summer d) Earth rotates more slowly in winter, faster in summer e) Earth's Moon blocks more sunlight from reaching Earth in winter than in summer - ANSb) Earth is titled with respect to the sun by about 23.5 degrees
3. As compared to a cool star, a hotter star emits: a) shorter wavelength, lower frequency, redder color b) shorter wavelength, higher frequency, redder color c) shorter wavelength, lower frequency, bluer color d) shorter wavelength, higher frequency, bluer color e) longer wavelength, higher frequency, bluer color - ANSd) shorter wavelength, higher frequency, bluer color
4. At approximately what time does the third quarter Moon rise?

a) 9pm b) 6pm c) noon d) 6am e) midnight - ANSe) midnight

5. The electrons in a cloud of hydrogen gas are making the transition from excited states to the ground state. What does the spectrum of this cloud of gas look like? a) It will be completely black at all wavelengths. b) It will be bright at every wavelength, giving off some radio waves, some visible light, and X-rays. c) It will consist of a few bright emission lines at very specific wavelengths. d) It will be bright at most colors, but with some dark absorption lines at very specific wavelengths. e) It will be identical to the spectrum of the Sun. - ANSc) It will consist of a few bright emission lines at very specific wavelengths.
6. If Earth had its orbit changed so that at all points along its orbit it was always the same distance from the Sun (circular orbit), how would this affect the seasons on Earth? a) longer than they are now. b) reversed in order (winter, fall, summer, spring). c) the same as they are now. d) there would no longer be seasons. e) shorter than they are now. - ANSc) the same as they are now.
7. I detect a star giving off more ultraviolet light than green light. What property of the star can I estimate with this information? a) Its chemical composition b) Its temperature c) Its density d) Its age e) Its distance from Earth - ANSb) Its temperature

8. What do you expect the spectrum of an object that is 1,000,000 Kelvin to be like? a) It should give off less total light than the Sun. b) It should peak at violet wavelengths. c) It should peak at X-ray wavelengths. d) It should give off about 10 times more total light than the Sun. e) It should peak at radio wavelengths. - ANSc) It should peak at X-ray wavelengths.
9. What time of year is it dark all day (and night) at the South pole? a) never b) June c) December d) September e) March - ANSb) June
10. A planet with its rotation axis tilted by 40 degrees relative to its orbital plane around its star would: a) have dark all the time on the South pole during its winter b) have shorter days and nights than those of Earth c) have longer years than those of Earth d) have longer days and nights than those of Earth e) have dark all the time on the North pole during its summer - ANSa) have dark all the time on the South pole during its winter
11. The planets are seen in the Zodiac constellations because: a) they reach the zenith at noon during the fall equinox b) they orbit the Earth just like the Sun does c) they orbit the Sun in the same plane as the Earth does d) they reach the meridian at noon during the summer solstice e) they reach the zenith at noon during the summer solstice - ANSc) they orbit the Sun in the same place as the earth does
12. What makes a transition from a higher energy state to a lower energy state when a photon is emitted by an atom? a) electron

b) proton c) photon d) graviton e) neutron - ANSa) electron

13. Which of the following is FALSE? a) Light, radio, ultraviolet, and gamma rays are all forms of electromagnetic radiation. b) Emission spectra are characterized by narrow, bright lines of different colors. c) An absorption spectrum appears as a continuous spectrum interrupted by a series of dark lines. d) The energy of a photon is inversely proportional to the wavelength of the radiation. e) The wavelengths of the emission lines produced by an element are different from the wavelengths of an absorption line produced by the same element. - ANSe) The wavelengths of the emission lines produced by an element are different from the wavelengths of an absorption line produced by the same element.
14. One of the lines of Hydrogen has a wavelength of 121.6 nm. If a cloud of Hydrogen gas is moving TOWARDS us at 200km/s, what will we detect? a) An emission line in the cloud's spectrum with a wavelength shorter than 121.6 nm. b) An emission line in the cloud's spectrum with a wavelength longer than 121.6 nm. c) An emission line in the cloud's spectrum with a wavelength of exactly 121.6 nm. d) This cloud will not emit a spectrum at all. e) A continuous spectrum with an absorption line at exactly 121.6 nm. - ANSa) An emission line in the cloud's spectrum with a wavelength shorter than 121.6 nm.
15. Why does light come in different colors? a) differences in the wavelength b) it travels at different speeds c) warping of space it travels through d) differences in intensity of radiation e) bending of light in space - ANSa) differences in the wavelength

16. Say you are in the bottom of Happy Valley. How does the force of gravity compare to what it would be on top of Mount Nittany? a) two times less in Happy Valley than on Mount Nittany b) two times greater in Happy Valley than on Mount Nittany c) slightly greater in Happy Valley than on Mount Nittany d) exactly equal in Happy Valley and on Mount Nittany e) slightly less in Happy Valley than on Mount Nittany - ANSc) slightly greater in Happy Valley than on Mount Nittany
17. What kind of a telescope would have to be put in space to be effective? a) optical b) radio c) reflecting d) X-ray e) refracting - ANSd) X-ray
18. Dark lines in an absorption spectrum represent: a) particular energies of light coming from a distant object that are absorbed by material in between. b) flaws in the telescopes and spectroscopes that astronomers use to measure spectra. c) hotter regions in the object that is emitting the spectrum. d) regions where light travels more slowly and is not able to reach us. e) photons emitted when an electron jumps from a higher to a lower energy level. - ANSa) particular energies of light coming from a distant object that are absorbed by material in between.
19. If the mass of the Sun were cut in half, how would the force between the Sun and the Earth change? a) it would quadruple b) it would double c) it would remain unchanged d) it would decrease by a factor of four e) it would decrease by a factor of two - ANSe) it would decrease by a factor of two
20. In what way does a 30 meter telescope outperform a 10 meter telescope? a) The images of the 30 meter are 9 times brighter than those of a 10 meter.

b) The images of the 30 meter are 3 times brighter than those of a 10 meter. c) All objects observed by the 30 meter telescope will appear larger than those of the 10 meter. d) The 30 meter can observe light with a wavelength 3 times longer than that of the 10 meter. e) The images of the 30 meter are 1/3rd as large as those of a 10 meter. - ANSa) The images of the 30 meter are 9 times brighter than those of a 10 meter.

21. On a planet whose Moon is in the same orbital plane as the planet's orbit around its star, how often will solar eclipses occur? a) Twice every orbit of its moon (twice a month). b) Once every orbit of the planet around its Sun (its year). c) Twice every rotation of the planet (twice a day). d) Once every orbit of its moon (its month). e) Once every rotation of the planet (its day). - ANSd) Once every orbit of its moon (its month).
22. Say that our Moon was Full on May 1, 2007. When was the next First Quarter phase after that Full Moon? a) May 15 b) June 1 c) May 22 d) May 8 e) May 4 - ANSc) May 22
23. Why does a neon light appear red? a) It produces ultraviolet light, which to our eyes appears red. b) The atoms of neon have electrons that are primarily red. c) It gives off an emission spectrum with mostly red spectral lines. d) The metal filament inside is heated to 1000 Kelvin. e) The gas in the bulb absorbers every other color besides red. - ANSc) It gives off an emission spectrum with mostly red spectral lines.
24. Why don't we see the constellation Orion all year? a) As the Earth orbits the Sun, its nighttime side points to different constellations at different points along its orbit. b) It is frequently eclipsed by the Moon. c) When we are close to Orion it appears bright, but when we are far away it gets too faint to see.

d) Half the year it is visible in North America, and the other half in South America. e) It is not along the Ecliptic path and only the constellations of the Zodiac are visible all year round. - ANSa) As the Earth orbits the Sun, its nighttime side points to different constellations at different points along its orbit.

25. From Earth, in which type of constellation might you find the planet Saturn? a) Only in a constellation near the South polar axis of Earth b) Only in a Zodiac constellation c) Only in the same constellation as the Moon. d) Only in a constellation near the North polar axis of Earth e) Only in the same constellation as the Sun. - ANSb) Only in a Zodiac constellation
26. What is the main constituent of the atmosphere of Venus? a) helium b) hydrogen c) oxygen d) carbon dioxide e) nitrogen - ANSd) carbon dioxide
27. The escape velocity needed for an atom in the atmosphere of a planet to escape the gravitational pull of the planet is smaller if: a) the radius of the planet is smaller b) the planet is farther from the Sun c) the mass of the atom is larger d) the temperature of the gas in the atmosphere is lower e) the mass of the planet is smaller - ANSe) the mass of the planet is smaller
28. The planets of the solar system were formed: a) by the collapse of a single higher mass star into a black hole

b) by a near collision between the Sun and a nearby star c) as condensations/accretions of hot gases ejected from the Sun d) by the accumulation of many comets e) as individual condensation/accretion centers in a rotating solar nebula - ANSe) as individual condensation/accretion centers in a rotating solar nebula

29. Which of the following is true about Neptune? a) Its atmospheric composition and rings are most like Saturn's. b) Its atmospheric composition is most like Saturn's, but its rings are more like those of Uranus and Jupiter. c) Its atmospheric composition is most like Uranus and its rings are like those of Uranus and Jupiter. d) Its atmospheric composition and its rings are most like Jupiter's. e) It is more like the Earth than it is like any of the other giant planets. - ANSc) Its atmospheric composition is most like Uranus and its rings are like those of Uranus and Jupiter.
30. The Oort Cloud is thought to be: a) The cloud of gas and dust from which our solar system formed. b) A cloud of asteroids moving between the orbits of Mars and Jupiter. c) A cloud of debris that occasionally encounters the Earth, causing a meteor shower. d) A spherical cloud of comets surrounding the solar system. e) A planetary nebula surrounding the second nearest star to the solar system. - ANSd) A spherical cloud of comets surrounding the solar system.
31. Venus is visible to us: a) only during its new phase. b) only near sunrise or sunset. c) only in the summer. d) only in the winter. e) only during the several hours around midnight. - ANSb) only near sunrise or sunset.

32. Planet A has an orbit with a semi-major axis of 3 Astronomical Units. Planet B has an orbit with a semi-major axis of 12 Astronomical Units. How does the orbital period compare between the two planets? Use P squared = a cubed to estimate. a) Planet B has an orbital period 64 times longer than Planet A. b) Planet B has an orbital period 4 times shorter than Planet A. c) Planet B has an orbital period 4 times longer than Planet A. d) Planet B has an orbital period 8 times longer than Planet A. e) Planet B has an orbital period 64 times shorter than Planet A. - ANSd) Planet B has an orbital period 8 times longer than Planet A.
33. How would an inflated landing module bounce if it were dropped onto the surface of Earth from the same altitude as it was on Mars? a) It would bounce higher sometimes and lower sometimes on the surface of Mars. b) It would not bounce at all. c) It would bounce higher and slower than it did on the surface of Mars. d) It would bounce lower and fewer times than it did on the surface of Mars. e) It would bounce higher and more times than it did on the surface of Mars. - ANSd) It would bounce lower and fewer times than it did on the surface of Mars.
34. How does Pluto's mass compare with that of Earth's Moon? a) The Moon is roughly 7 times more massive than Pluto. b) Pluto is roughly 7 times more massive that the Moon. c) They both have the same mass. d) Pluto's mass is roughly 1/20th the mass of the Moon. e) The Moon's mass is roughly 1/20th the mass of Pluto. - ANSa) The Moon is roughly 7 times more massive than Pluto.
35. How was Earth's Moon formed, according to the currently most-accepted theory? a) It formed from the collapsing protoplanetary disk at the same time as Earth. b) It was a passing body captured by Earth's gravity. c) It formed from debris produced by the collision of a Mars-sized object with the Earth.

d) A gigantic volcano on Earth threw out the material that became the Moon. e) No one really knows. - ANSc) It formed from debris produced by the collision of a Mars-sized object with the Earth.

36. Why does Mars have seasons? a) Mars has an atmosphere which deteriorates and regenerates on a yearly cycle. 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 orbit is circular. e) Its axis is tilted relative to its orbital plane. - ANSe) Its axis is tilted relative to its orbital plane.
37. Which planet is able to retain the largest (by radius and by volume) atmosphere? a) Mars b) Jupiter c) Earth d) Venus e) Mercury - ANSb) Jupiter
38. The process of formation of the Solar System a) involved the Sun forming from the collapse of a large planet. b) began about 10 million years ago. c) led to the formation of the most massive planets closest to the Sun and the least massive farthest away. d) involved a spinning cloud of gas that remained spherical until after the planets and Sun formed. e) took only a small fraction of the age of the Solar System. - ANSe) took only a small fraction of the age of the Solar System.
39. Which is smallest? a) Saturn's moon Encledus b) Saturn's moon Titan c) Mercury d) Earth

e) Jupiter's moon Ganymede - ANSa) Saturn's moon Encledus

40. Which of the following is typical of a Terrestrial planet? a) evidence for volcanic activity b) a hydrogen-rich composition c) an average density much less than that of rock d) the presence many moons e) an orbit outside the asteroid belt - ANSa) evidence for volcanic activity
41. What are the most abundant gases in Jupiter's atmosphere? a) methane and ammonia b) methane and hydrogen c) hydrogen and ammonia d) hydrogen and helium e) water vapor and ozone - ANSd) hydrogen and helium
42. Which has the lowest average density? a) Mercury b) Venus c) Uranus d) Mars e) the Moon - ANSc) Uranus
43. Which of these planets has rings? a) Jupiter b) Pluto c) Venus d) Mars e) Mercury - ANSa) Jupiter
44. Which fact about Mars is NOT true? a) There are giant volcanoes on Mars, larger than any on Earth. b) There was once water on the surface of Mars. c) The Viking spacecraft landed on Mars in 1976. d) It is always colder than freezing on Mars surface. e) Mars has a thicker atmosphere than Earth does. - ANSe) Mars has a thicker atmosphere than Earth does.

45. Mars has a mass that is 1/10th the mass of the Earth and a radius that is 1/2 the radius of Earth. Compare the force of gravity on Mar's surface to that on the surface of Earth using the proportional relationship F is proportional to M/R a) Gravity on Mars is 10 times stronger than on Earth. b) Gravity on Mars is 1/10th as strong as on Earth. c) Gravity on Mars is 4/10ths as strong as on Earth. d) Gravity on Mars is 4 times stronger than on Earth. e) Gravity on Mars is equal to gravity on Earth. - ANSc) Gravity on Mars is 4/10ths as strong as on Earth.
46. The Sun is at one focus of the elliptical orbit of the Earth around the Sun. What is at the other focus? a) Nothing. b) The Earth. c) Mars. d) The Moon. e) Jupiter. - ANSa) Nothing.
47. Which of the following are the jovian planets? a) Jupiter, Saturn, Uranus, Neptune b) Earth, Mars, Jupiter, Saturn c) Uranus, Neptune, and Pluto d) Mercury, Jupiter, and Saturn e) Mercury, Venus, Earth, Mars - ANSa) Jupiter, Saturn, Uranus, Neptune
48. Which of the following statements is TRUE? a) Jupiter's solid surface lies just below the cloud layers visible from Earth. b) The Great Red Spot is a dust storm near the South polar cap of Mars. c) There is no evidence to suggest that either Jupiter or Saturn has a rocky core. d) Neither Uranus or Neptune have ring systems. e) The planet Uranus is blue-green and virtually featureless. - ANSe) The planet Uranus is blue-green and virtually featureless.
49. The surface of Venus is hotter than the surface of Mercury because: a) Venus is smaller than Mercury so it does not require so much energy to heat it.

b) of the volcanic activity that occurs on Venus. c) Mercury's atmosphere prevents radiation from penetrating through to its surface. d) Venus is closer to the Sun than Mercury. e) Venus is more massive and is able to retain a thick atmosphere. - ANSe) Venus is more massive and is able to retain a thick atmosphere.

50. What fraction of the solar system's mass is in the Sun? a) About 50% b) About 99% c) About 10% d) Less than 1% e) About 75% - ANSb) About 99%
51. How do astronomers measure the temperature of stars? a) The inverse square law is used. b) Temperature is determined from the radius of the star that is measured by radar. c) By looking at which absorption lines are present in the star's spectrum. d) The rate of change of the color of the star is measured. e) By comparing the star's absolute and apparent brightness. - ANSc) By looking at which absorption lines are present in the star's spectrum.
52. How do we determine the age of a star cluster? a) by identifying the type of stars that have just turned off the main sequence b) spectroscopic parallax c) by determining the spectral types of the faintest stars in the cluster d) radioactive dating e) by comparing the ages of white dwarfs and red giants - ANSa) by identifying the type of stars that have just turned off the main sequence
53. A hypothetical star has a parallax of 0.05 arcseconds. How far away is it? a) 50 parsecs b) 10 parsecs c) 5 parsecs d) 0.05 parsecs e) 20 parsecs - ANSe) 20 parsecs
54. A 10 solar mass star: a) will eventually develop an Iron core

b) can never produce a supernova c) will end its life as a white dwarf d) will live longer than the Sun on the Main Sequence e) can never become a neutron star - ANSa) will eventually develop an Iron core

55. A star that is twice the mass of our Sun would have a habitable zone that: a) includes Mars but not the Earth b) includes Venus but not the Earth c) includes Neptune only d) includes both Venus and the Earth e) includes Mercury only - ANSa) includes Mars but not the Earth
56. The largest fraction of nearby stars (e.g. within 100 light years) are: a) neutron stars b) Sun-like stars c) blue Main Sequence stars d) red dwarfs e) blue supergiants - ANSd) red dwarfs
57. What happens when a planet passes in front of its star (i.e. between the star and us)? a) The star increases in brightness and the star moves away from us b) The star increases in brightness and the star moves towards us c) The star decreases in brightness and the star moves towards us d) The star does not change in brightness or move relative to us e) The star decreases in brightness and the star moves away from us - ANSc) The star decreases in brightness and the star moves towards us
58. A 16 solar mass main sequence star is at a smaller distance than a 1 solar mass main sequence star. Which star appears brighter?

a) cannot tell with the information given b) stars are approximately the same brightness c) the 16 solar mass main sequence star d) depends on the phase of the Moon e) the 1 solar mass main sequence star - ANSc) the 16 solar mass main sequence star

59. The event horizon of a black hole is: a) the distance at which a star is torn apart by tidal forces b) the minimum distance from which light can escape c) the distance at which a human body is torn apart by tidal forces d) the distance from which we can see inside the black hole e) the point of infinite density. - ANSb) the minimum distance from which light can escape
60. A cold, irregularly shaped region in the interstellar medium that diminishes or completely obscures the light from background stars is called a/an: a) irregular galaxy b) dark dust cloud c) emission nebula d) reflection nebula e) planetary nebula - ANSb) dark dust cloud
61. In nuclear fusion, energy is produced because: a) Hydrogen is not stable. b) gravity leads to collapse. c) the mass of the reacting chemicals is larger than that of the products. d) positrons are produced. e) of the energetic impact of collisions. - ANSc) the mass of the reacting chemicals is larger than that of the products.
62. Is the Milky Way Galaxy currently participating in Galactic cannibalism, and if so what is it devouring?

a) The Milky Way is not participating in Galactic cannibalism at this time, but did billions of years ago. b) It is currently pulling apart and "eating" the Sagittarius Dwarf Galaxy. c) The Milky Way has never participated in Galactic cannibalism at any time. d) It is presently in the final stages of merger with the Andromeda Galaxy. e) It is eating the globular star clusters that are in a spherical distribution in its halo. - ANSb) It is currently pulling apart and "eating" the Sagittarius Dwarf Galaxy.

63. Fill in the blank in the following chemical reaction that occurs in the Sun: Deuterium+ proton = ?? + energy: a) hydrogen- b) helium- c) deuterium- d) carbon- e) helium-4 - ANSb) helium-
64. What happens when you drop a clock into a black hole? a) The clock appears to be advancing at its normal rate both from the point of view of an outside observer and from the point of view of an observer falling with the clock. b) The clock appears to be advancing slowly from the point of view of an outside observer, but normally for an observer falling with the clock. c) The clock appears to be advancing rapidly both from the point of view of an outside observer and from the point of view of an observer falling with the clock. d) The clock appears to be advancing rapidly from the point of view of an outside observer, but normally for an observer falling with the clock. e) The clock appears to be advancing slowly both from the point of view of an outside observer and from the point of view of an observer falling with the clock. - ANSb) The clock appears to be advancing slowly from the point of view of an outside observer, but normally for an observer falling with the clock.
65. In which part of the Sun are gamma rays produced? a) corona b) core

c) chromosphere d) convection zone e) photosphere - ANSb) core

66. Which is the longest time? a) the time it takes for a photon to pass through the radiative zone of the Sun b) the time it takes a photon to pass through the corona of the Sun c) one hour d) the time it takes a photon to pass from the photosphere of the Sun to the Earth e) the time it take light to traverse the convective zone of the Sun - ANSa) the time it takes for a photon to pass through the radiative zone of the Sun
67. Which star is the closest if all have the same apparent brightness? a) a main sequence star with a luminosity 100 times that of the Sun b) a temperature 6000 K main sequence star c) a temperature 10000 K main sequence star d) white dwarf e) a red giant - ANSd) white dwarf
68. If two stars are the same temperature, how can one be more luminous than the other? a) It can have a larger reaction rate in the core. b) It can be a different spectral type. c) It can have stronger magnetic fields. d) It can be closer. e) It can have a larger radius. - ANSe) It can have a larger radius.
69. A planetary nebula: a) is the ejected envelope of a low to intermediate mass star b) is what stars and planets are made of

c) contains a black hole at the center d) lasts very long in the life of every star e) is a fuzzy planet - ANSa) is the ejected envelope of a low to intermediate mass star

70. A supernova can occur when: a) a massive star is on the Main Sequence b) the center of a 1 solar mass star stops burning Hydrogen in its core c) material from a companion star falls onto a white dwarf d) material from a red supergiant falls into a black hole e) a low mass star is on the Main Sequence - ANSc) material from a companion star falls onto a white dwarf
71. Which of the following is TRUE? a) The Eagle nebula is an example of a planetary nebula. b) A brown dwarf is a case where the temperature of a protostar did not grow enough to burn Hydrogen. c) Bok globules are very luminous regions in the interstellar medium. d) All Messier objects are actually comets. e) A supernova explosion occurs just before a massive star forms. - ANSb) A brown dwarf is a case where the temperature of a protostar did not grow enough to burn Hydrogen.
72. The stars in the halo of our galaxy are: a) never in globular clusters. b) in a very flat distribution. c) older and redder than those in the disk. d) not affected by reddening and extinction. e) older and bluer than those in the disk. - ANSc) older and redder than those in the disk.
73. How can we see through the dusty plane of the Milky Way disk in order to study star formation? a) Use the radial velocity technique. b) Look at visible radiation from space with the Hubble Space Telescope.

c) Use an optical telescope from the ground with a higher angular resolution. d) Look at infrared radiation with the Spitzer Space Telescope. e) Obtain a rotation curve using the gas in the Milky Way disk. - ANSd) Look at infrared radiation with the Spitzer Space Telescope.

74. Which of the following is FALSE? a) A star with spectral type of B is sometimes hotter than a star with spectral type A, and sometimes colder. b) The lifetimes of stars range from a few million years for the most massive to much more than 14 billion years for less massive stars. c) Parallax can be used to measure the distances to the nearest stars. d) The H-R diagram can be used to find the luminosity of a main sequence star, given its spectral type. e) Transits and radar represent the bottom rung of the distance ladder. - ANSa) A star with spectral type of B is sometimes hotter than a star with spectral type A, and sometimes colder.
75. What element is only produced in a supernova explosion? a) oxygen b) carbon c) hydrogen d) gold e) iron - ANSd) gold
76. Which is true about cold dark matter? a) Cold dark matter interacts strongly with ordinary baryonic matter via the strong force. b) Cold dark matter particles travel faster than the speed of light. c) Cold dark matter particles travel more slowly than hot dark matter particles. d) Cold dark matter exists only within planets and stars but not in other parts of galaxies or intergalactic space. e) Cold dark matter emits X-rays, but no other forms of radiation. - ANSc) Cold dark matter particles travel more slowly than hot dark matter particles.
77. Which source is the most luminous (or would be, if all its energy were output in visible light)? a) The Sun.

b) A quasar. c) A nuclear power plant. d) A gamma-ray burst. e) A supernova. - ANSd) A gamma-ray burst.

78. Which force holds the quarks together within a proton? a) Gravity, through exchange of gravitons. b) Proton/neutron mutual attraction forces. c) The 'strong' force, through exchange of gluons. d) Electromagnetic, through exchange of photons. e) The 'weak' force, through nuclear decay. - ANSc) The 'strong' force, through exchange of gluons.
79. Which is a reason that we know dark energy is a major component of the universe? a) The universe would not be 2.7 degrees Kelvin today without dark energy. b) The gravity due to regular matter in the universe would have started it contracting again by now without dark energy. c) Supernovae would not occur without dark energy. d) Dark energy is needed in order that light can escape from supermassive black holes. e) The universe is flat and regular matter doesn't contribute enough energy density. - ANSe) The universe is flat and regular matter doesn't contribute enough energy density.
80. When examining a spectrum of a particular galaxy, an astronomer notices that the spectral lines are shifted toward shorter wavelengths. What does this mean? a) the element Helium is present in that galaxy b) the galaxy is moving away from us c) the galaxy is very likely to be one of the nearest galaxies to the Milky Way d) the entire Universe is contracting e) the galaxy is rotating very rapidly - ANSc) the galaxy is very likely to be one of the nearest galaxies to the Milky Way

81. Why can't we see back the whole way to the Big Bang? a) Radiation is blueshifted out of the visible range. b) It would take too long for light to travel that far. c) Our telescopes could never be powerful enough. d) The radiation scatters off matter frequently so the Universe is opaque. e) Not enough photons were produced. - ANSd) The radiation scatters off matter frequently so the Universe is opaque.
82. Which is the smallest? a) The distance from the Sun to the center of the Milky Way Galaxy b) The distance from the Sun to the Andromeda Galaxy c) The Solar System. d) The distance from the Sun to the Virgo cluster of galaxies e) The distance from the Sun to its nearest neighboring star - ANSc) The Solar System.
83. Which one of the following is TRUE? a) Irregular galaxies rarely have star formation taking place in them. b) Galaxy collisions destroy most of the stars in the galaxies involved. c) Most elliptical galaxies contain only young stars. d) Most galaxies appear to be approaching the Milky Way Galaxy. e) There is a supermassive black hole in the center of the Milky Way Galaxy - ANSe) There is a supermassive black hole in the center of the Milky Way Galaxy
84. What type of boson is responsible for the electromagnetic force? a) gluon b) photon c) electron d) graviton e) W boson - ANSb) photon
85. An up quark has charge +2/3, a down quark has charge -1/3, and a strange quark has charge -1/3. The Sigma0 particle is formed by a combination of two down quarks and one strange quark. What is its charge? a) -1 b) +1/3

c) 1 d) 0 e) -1/3 - ANSa) -1

86. Which of the following is TRUE? a) It is possible for galaxies that are very distant to actually move through space at a speed several times the speed of light. b) A redshift occurs when a photon loses energy and slows down as it moves through space. c) We see distant galaxies as they were billions or even tens of billions of years ago. d) We measure a redshift for roughly half of the galaxies that we observe, and for the others we measure a blueshift. e) The center of the universe is located at a point about 200 Mpc from us in the center of a cluster of galaxies. - ANSc) We see distant galaxies as they were billions or even tens of billions of years ago.
87. Among these choices, which is the first thing that happens in the history of the universe? a) formation of nuclei of helium b) binding of electrons to nuclei c) first stars form d) universe becomes transparent e) first supernova explosions occur - ANSa) formation of nuclei of helium
88. Which of the following statements is definitely FALSE? a) String theory suggests that extra dimensions may exist beyond our three known spatial dimensions and time. b) There is an absence of space beyond the boundaries of our observable universe. c) There is a theory of quantum mechanics in which new universes split from ours at every random event. d) New universes may break off from ours as it expands. e) Universes with the largest number of black holes are favored in the theory of natural

selection of universes. - ANSb) There is an absence of space beyond the boundaries of our observable universe.

89. What do quasars look like? a) Fuzzy, extended patches of light. b) Large concentrations of dark matter. c) Individual stars in the Milky Way. d) Glowing gas clouds. e) Planetary nebulae - ANSc) Individual stars in the Milky Way.
90. Does the existence of quasars imply that radiation can escape a black hole? a) No, the emission of radiation occurs before material falls in through the event horizon. b) Yes, the laws of physics break down so that material travels faster than the speed of light near quasars. c) Yes, radiation can escape because the mass of a photon is zero. d) Quasars have nothing to do with black holes. e) Quasars do not produce radiation of any sort, so there is no contradiction. - ANSa) No, the emission of radiation occurs before material falls in through the event horizon.
91. Which of the following makes a meson? a) a photon and a graviton b) an up quark and an anti-down quark c) three up quarks d) a charm quark and a strange quark e) two down quarks and an anti-up quark - ANSb) an up quark and an anti-down quark
92. What property of dark matter leads to it keeping galaxy clusters together? a) It produces gravity due to its mass. b) It contains a cosmological constant.

c) It produces the electromagnetic force due to its charge. d) It carries the strong force. e) It has high adhesion so galaxies stick to it. - ANSa) It produces gravity due to its mass.

93. What did the Wilkinson Microwave Anisotropy Probe (WMAP) measure? a) differences in the temperature of radiation coming from the Big Bang from different directions b) the existence of a particle emitted through negative gravity c) the epoch of the formation of the first stars d) the existence of low mass dark matter particles e) the presence of supermassive black holes in the centers of nearly all galaxies - ANSa) differences in the temperature of radiation coming from the Big Bang from different directions
94. What fraction of the energy density of the universe consists of dark matter? a) 75 percent b) 1 percent c) 99 percent d) 21 percent e) 4 percent - ANSd) 21 percent
95. Compared to spiral galaxies, elliptical galaxies have... a) ...less gas, more dust, and more new star formation. b) ...more gas, more dust, and less new star formation. c) ...more gas, more dust, and more new star formation. d) ...less gas, less dust, and less new star formation. e) ...less gas, less dust, and more new star formation. - ANSd) ...less gas, less dust, and less new star formation.
96. What happens to the planets in a galaxy when that galaxy collides with another galaxy? a) They are pulled out of their orbits by the tidal forces of the intruding galaxy. b) Smaller stars collide with each other, forming more massive stars which swallow the planets.

c) Nothing, because the spaces between stellar systems in a galaxy is much larger than their size. d) They accrete a whole lot of new matter and become stars themselves. e) They ignite completely and explode violently. - ANSc) Nothing, because the spaces between stellar systems in a galaxy is much larger than their size.

97. If extra dimensions do exist, why wouldn't we see obvious evidence for them in everyday life? a) because they affect only the strength of the strong force and not of any other forces b) They are the same as the dimensions that we do perceive. c) They will only be present in the distant future. d) They were only present at the time of inflation and before. e) They would be quite small and hard to detect. - ANSe) They would be quite small and hard to detect.
98. How do astronomers measure the mass of a supermassive black hole? a) by comparing its apparent magnitude to its absolute brightness b) by comparing its X-ray luminosity to its radio luminosity c) using the formula E = mc2 d) by measuring the speed at which stars move in its vicinity e) by measuring its parallax - ANSd) by measuring the speed at which stars move in its vicinity
99. What produces the afterglow of a gamma-ray burst? a) Collisions between planets and stars. b) Repeated explosions of the central star. c) Gradual escape of particles from a central black hole. d) X-rays travel more slowly through space than other types of radiation so they produce an afterglow. e) Collision of expanding stellar material with gas and dust in the interstellar medium. - ANSe) Collision of expanding stellar material with gas and dust in the interstellar medium.
100. What produces the afterglow of a gamma-ray burst? a) Gradual escape of particles from a central black hole. b) X-rays travel more slowly through space than other types of radiation so they produce