The Essential Cosmic Perspective Our Place in the Universe.docx

The Essential Cosmic Perspective Our Place in the Universe 1.1 Multiple Choice Questions 1) The farthest bright galaxies that modern telescopes are capable of seeing are up to A) 1 million light years away. B) 10 million light years away. C) 1 billion light years away. D) 10 billion light years away. E) 1 trillion light years away Answer: D 2) Suppose we imagine the Sun to be about the size of a grapefruit. How big an area would the orbits of the nine planets of the Solar System cover? A) the size of a typical dorm room B) the size of a typical campus building C) the size of a typical campus D) the size of a small city E) the size of a western state (e.g.,Colorado) Answer: C 3) Earth is made mostly of metals and rocks. Where did this material come from? A) It was produced in the Big Bang. B) It was created by chemical reactions in interstellar space. C) It was produced by nuclear fusion in stars. D) It was made by our Sun. E) It was made by nuclear fission of uranium and other radioactive materials. Answer: C 4) What is nuclear fusion? A) an explosion caused by putting together two volatile chemicals B) the process of splitting nuclei to produce energy C) the process of turning matter into pure energy D) the process of combining lightweight nuclei to make heavier nuclei E) a process that only occurs in bombs Answer: D 5) Which of the following statements does not use the term light-year in an appropriate way? A) It's about 4 light-years from here to Alpha Centauri. B) It will take me light-years to complete this homework assignment. C) A light-year is about 10 trillion kilometers. D) It will take the Voyager spacecraft about 20,000 years to travel just 1 light-year. E) The Milky Way Galaxy is about 100,000 light-years in diameter. Answer: B 6) Light takes approximately one second to travel from the Earth to the Moon. This means that the moon is approximately A) 1 astronomical unit from the Earth B) 1 light year from the Earth C) 3,000 kilometers from the Earth D) 300,000 kilometers from the Earth E) twice the distance from the Earth to the Sun Answer: C 7) One light-hour is the distance that light travels in an hour. How far is this, in kilometers? (Recall that the speed of light is 300,000 km/s.) A) 300,000 km B) 18 million km C) 100 million km D) 1.08 billion km E) 9.46 trillion km Answer: D 8) Suppose we look at a photograph of many galaxies. Assuming that all galaxies formed at the same time after the Big Bang, which galaxy appears to us as the youngest? A) The galaxy that is furthest from us. B) The galaxy that is closest to us. C) The galaxy that appears largest to us. D) The galaxy that appears bluest to us. E) All galaxies would appear to have the same age. Answer: A 9) Suppose we imagine the Sun to be about the size of a grapefruit. Which of the following describes the size and distance of Earth on the same scale? A) Earth is the size of a point about 1 meter away from the Sun. B) Earth is the size of a golf ball about 1 meter away from the Sun. C) Earth is the size of a point about 15 meters away from the Sun. D) Earth is the size of a golf ball about 15 meters away from the Sun. E) Earth is the size of a marble about 25 miles away from the Sun. Answer: C 10) Which of the following correctly describes the concept of galactic recycling? A) Stars near the center of the Milky Way are continually recycled to the outskirts of the disk by their orbital motion. B) Life is continuously being spread from star to star in the Milky Way. C) New stars are continuously being formed in the Milky Way out of gas that has been ejected from a previous generation of stars. D) New galaxies are continuously being formed out of gas ejected from a previous generation of galaxies. E) In the formation of a star, no matter is wasted as all excess material ends up recycled into planets. Answer: C 11) What is the Sun mainly made of? A) hydrogen and oxygen B) hydrogen and helium C) carbon and nitrogen D) oxygen and carbon E) nearly equal portions of all the elements Answer: B 12) Which of the following is smallest? A) size of a typical planet B) 1 light-second C) 1 AU D) size of a typical star Answer: A 13) Which of the following is largest? A) size of a typical galaxy B) size of Pluto's orbit C) distance to the nearest star (other than our Sun) D) 1 light-year Answer: A 14) On the 1-to-10-billion scale, about how far is it to the nearest stars besides the Sun? A) 4 kilometers B) 400 kilometers C) 1,000 kilometers D) 4,400 kilometers E) 10,000 kilometers Answer: D 15) Suppose we imagine the Sun to be about the size of a grapefruit. How far away are the nearest stars (the three stars of Alpha Centauri)? A) the length of a football field B) 2.5 miles C) 250 miles D) 2,500 miles E) 25,000 miles Answer: D 16) If we use 1 millimeter to represent 1 light-year, how large in diameter is the Milky Way Galaxy? A) 100 millimeters B) 100 meters C) 1 kilometer D) 100 kilometers E) 1 million millimeters Answer: B 17) Which of the following best describes the Milky Way Galaxy? A) a spiral galaxy with a disk about 100,000 light-years in diameter and containing between 100 billion and 1 trillion stars B) a spiral galaxy with a disk about a billion kilometers in diameter and containing between 100 million and 1 billion stars C) a spiral galaxy with a disk about 100,000 light-years in diameter and containing about 100,000 stars D) a spherically shaped collection of stars including our solar system and about a dozen other solar systems, stretching about 4 light-years in diameter E) a spherically shaped collection of about 1 million stars that is about 100 light-years in diameter Answer: A 18) How many galaxies are there in the observable universe? A) roughly (within a factor of 10) the same as the number of stars in our galaxy B) roughly a thousand times more than the number of stars in our galaxy C) about as many as the number of stars we see in the sky with our naked eyes D) about as many as the number of grains of sand on all the beaches on Earth E) infinity Answer: A 19) On the scale of the cosmic calendar, in which the history of the universe is compressed to 1 year, how long has human civilization (i.e., since ancient Egypt) existed? A) about half the year B) about a month C) a few hours D) a few seconds E) less than a millionth of a second Answer: D 20) On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did the dinosaurs become extinct? A) in late December B) in late November C) in late October D) in late September E) in late August Answer: A 21) On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did Kepler and Galileo first discover that we live on a planet in a solar system? A) 1 second ago B) 1 day ago C) 1 week ago D) December 25 E) December 30 Answer: A 22) Approximately how fast is a person located at the Earth's equator travelling due to the rotation of the Earth? A) 17,000 km/hr B) 1,700 km/hr C) 170 km/hr D) 17 km/hr E) not moving at all Answer: B 23) How long does it take our solar system to complete one orbit around the Milky Way Galaxy? A) 10 thousand years B) 230 thousand years C) 1 million years D) 100 million years E) 230 million years Answer: E 24) Which of the following statements about the Milky Way Galaxy is not true? A) It contains between 100 billion and 1 trillion stars. B) Our solar system is located very close to the center of the Milky Way Galaxy. C) The galaxy is about 100,000 light-years in diameter. D) One rotation of the galaxy takes about 200 million years. Answer: B 25) Which of the following correctly lists speeds from slowest to fastest? A) Earth's speed of revolution about the Sun, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of rotation on its axis, the speed of our solar system orbiting the center of the Milky Way Galaxy, the speeds of very distant galaxies relative to us B) Earth's speed of rotation on its axis, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of revolution about the Sun, the speed of our solar system orbiting the center of the Milky Way Galaxy, the speeds of very distant galaxies relative to us C) The speeds of very distant galaxies relative to us, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of rotation on its axis, Earth's speed of revolution about the Sun, the speed of our solar system orbiting the center of the Milky Way Galaxy D) The speed of our solar system orbiting the center of the Milky Way Galaxy, Earth's speed of revolution about the Sun, Earth's speed of rotation on its axis, the speeds of very distant galaxies relative to us, typical speeds of stars in the local solar neighborhood relative to us E) Earth's speed of revolution about the Sun, Earth's speed of rotation on its axis, the speed of our solar system orbiting the center of the Milky Way Galaxy, typical speeds of stars in the local solar neighborhood relative to us, the speeds of very distant galaxies relative to us Answer: B 26) Most of the mass in the Milky Way Galaxy is located A) in the halo (above/below the disk). B) within the disk. C) in the stars in the spiral arms. D) in the gas and dust. E) in the central bulge of the galaxy. Answer: A 27) The distribution of the mass of the Milky Way Galaxy is determined by A) counting the number of stars. B) determining the amount of gas and dust. C) studying how stars are distributed in the Milky Way. D) studying the rotation of the galaxy. E) weighing various parts of the Milky Way. Answer: D 28) From the fact that virtually every galaxy is moving away from us and more distant galaxies are moving away from us at a faster rate than closer ones, we conclude that A) the Milky Way Galaxy is expanding. B) we are located at the center of the universe. C) the farthest galaxies will eventually be moving faster than the speed of light. D) the universe is expanding. E) the universe is shrinking. Answer: D 29) By studying distant galaxies in the 1920s, Hubble made the following important discovery that led us to conclude that the universe is expanding. A) All galaxies contain billions of stars, and all galaxies have spiral shapes. B) All galaxies were born at the same time, and all will die at the same time. C) All galaxies outside the Local Group are moving away from us, and the farther away they are, the faster they're going. D) All galaxies outside the Local Group are orbiting the Local Group. E) All galaxies outside the Local Group are moving away from us, and all are moving away at nearly the same speed. Answer: C 30) Imagine that we put a raisin cake into the oven, with each raisin separated from the others by 1 cm. An hour later, we take it out and the distances between raisins are 3 cm. If you lived in one of the raisins and watched the other raisins as the cake expanded, which of the following would you conclude? A) All raisins would be moving away from you at the same speed. B) More distant raisins would be moving away from you faster. C) More distant raisins would be moving away from you more slowly. D) It depends: If you lived in a raisin near the left side of the cake, you'd see other raisins moving away from you, but they'd be coming toward you if you lived in a raisin near the right side of the cake. Answer: B 1.2 True/False Questions 1) Our solar system is located in the center of the Milky Way Galaxy. Answer: FALSE 2) The solar system contains about 100 billion stars. Answer: FALSE 3) A typical supercluster contains no more than about 10,000 stars. Answer: FALSE 4) One light year is about 10 trillion kilometers. Answer: TRUE 5) In the grapefruit model of the solar system, it would take a few minutes to walk from the Sun to Pluto. Answer: TRUE 6) The observable universe is the same size today as it was a few billion years ago. Answer: FALSE 7) The Milky Way is moving further away from most other galaxies in the Universe. Answer: TRUE 8) No galaxies existed before the Big Bang. Answer: TRUE 9) Voyager 2 should reach the nearest stars (besides the Sun) in about 500 years. Answer: FALSE 10) Earth is always precisely 1 AU from the Sun. Answer: FALSE 1.3 Process of Science Questions 1) Light Travel Time: Because of the finite speed of light, we see more distant objects as they were in the past. For example, we see the star Alpha Centauri as it was 4.4 years ago, and the Andromeda Galaxy as it was 2.5 million years ago. Astronomers are often asked how we know that these objects still exist when we look at them in the night sky? How would you try to answer this question? Answer: Will vary. 2) The Observable Universe: How does the age of the universe (estimated at 14 billion years) introduce the concept of the "observable universe?" Suppose you feel, as do many astronomers, that the universe is much larger than the observable universe. Do you think there is any way to obtain direct evidence for this larger universe? Answer: Will vary. 3) A Life Calendar: Make a "life calendar" for hypothetical person. Assume that this person lived 80 years and represent the 80 year period as a single calendar year in which he or she was born on January 1st and died on December 31st. Estimate the calendar dates on which this person reached various life milestones. For example, when did he or she take their first step? Speak their first word? Start elementary school? Finish high school? When did he or she retire? Does your life calendar for this particular person give any insight into human lives in general? Answer: Will vary. 1.4 Short Answer Questions 1) The speed of light is 300,000 km/s. How far is a light-year? Be sure to show all work clearly on your calculation. Answer: 1 light-year = (speed of light) × (1 yr) = = 9,460,000,000,000 km 2) Briefly explain what we mean by the statement "The farther away we look in distance, the further back we look in time." Answer: It means that when we look at a distant object, we see it as it was some time in the past, rather than as it is now. This is because the light we see has taken time to travel from the object to us. 3) Starting from the Big Bang, briefly explain how our solar system came to contain the chemical elements necessary to make Earth and living organisms. Answer: The Big Bang produced hydrogen and helium. Over time, stars have converted about 2 percent of this material into heavier elements, including all the elements of which we and Earth are made. Stars expel this material through winds and explosions, and the galaxy recycles it into new generations of stars. When a new star system forms, it therefore contains the ingredients needed to make planets and living organisms. 4) Briefly explain why an expanding universe implies a beginning (called a Big Bang). Answer: The fact that the universe is expanding means the average distance between galaxies is growing, which implies that this average distance was smaller in the past. Extrapolating back in time, there must have been a time when the distance between galaxies (or their precursors) was zero, which must be the beginning of the universe. 5) Consider the following statement, and explain whether or not it is sensible: NASA hopes to build a new telescope that will allow us to see 100 million light-years into the past. Answer: Not sensible: uses light-years as a time. 6) Consider the following statement, and explain whether or not it is sensible: NASA hopes to build a new telescope that will allow us to see some galaxies as they appeared 8 billion years ago. Answer: Sensible: By looking to a distance of 8 billion light-years, we can see objects as they looked 8 billion years ago. 7) Consider the following statement, and explain whether or not it is sensible: The universe is between 10 and 16 billion light-years old. Answer: This statement does not make sense because it uses the term light-year as a time, rather than as a distance. 8) Consider the following statement, and explain whether or not it is sensible: It will take me light-years to complete this homework assignment. Answer: This statement does not make sense because it uses the term light-year as a time, rather than as a distance. 9) Consider the following statement, and explain whether or not it is sensible: Someday we may build spaceships capable of traveling at a speed of 1 light-second per hour. Answer: This statement is fine. A light-second is 300,000 kilometers, so it simply says that we'll someday build spaceships that can travel at a speed of 300,000 km/hr. 10) Briefly explain how the Sun generates energy. Answer: The Sun generates energy through nuclear fusion in its core, converting hydrogen into helium. This process releases energy because a small amount of the mass of the hydrogen is converted to energy. 11) Imagine that you could drive your car in space. Assume that you can drive at a constant speed of 100 kilometers per hour. Suppose you started driving from the Sun. How long would it take, in years, to reach Earth? Answer: t = = 1.5 million hours = 171 years It would take about 171 years to drive from the Sun to Earth. 12) Explain why it is so difficult to see planets around other stars. Answer: Planets are very faint compared to the stars they orbit. Moreover, they are very close to their parent star compared to the distance between stars. On the 1-to-10 billion scale, where the Sun is the size of a grapefruit and Earth is a pinhead about 15 meters way, the nearest star is several thousand kilometers away. Together, this makes it extremely difficult to distinguish the faint light of a planet from the star it orbits. (Nevertheless, massive Jupiter-like planets have been indirectly detected orbiting around nearby stars.) 13) Based on the idea of "spaceship Earth," write one or two paragraphs explaining why it is not the case that we are "just sitting here." Answer: Far from just sitting still, we on Earth are moving relative to the Sun, planets, stars, and even other galaxies. The rotation of Earth causes the most noticeable changes in the sky. This motion around Earth's axis causes the Sun and stars to appear to rise and set, producing what we call a "day." The revolution of Earth about the Sun produces the monthly changes of the constellations, the seasonal weather changes due to Earth's tilt, and the parallax of some stars. The precession of Earth's axis, a very slow movement that has a period of 26,000 years, causes the movement of the North Star, and the changing position of the equinoxes and solstices. The motion of the Sun relative to the stars in the local solar neighborhood is at an extremely fast speed, although barely noticeable. Over time, this movement causes the patterns of the stars in the sky to change. The rotation of the galaxy means that the entire solar system is also orbiting the center of the Milky Way. This also produces motions of stars and clouds of gas. The expansion of the universe, the fact that the space between most galaxies is increasing with time, means that almost all galaxies outside the Local Group are moving away from us, with the more distant ones moving away faster. All of these motions, although not felt by us on Earth, are observed by watching the sky and prove that we are not "just sitting here." 14) Consider the following statement, and explain whether or not it is sensible: Earth is always precisely 1 AU from the Sun. Answer: Not sensible: One AU is the average distance between Earth and the Sun. 1.5 Questions Based on MasteringAstronomy Tutorials 1) Light travels at 300,000 km/sec. About how far does light travel in 10 years? A) About 10 light-years B) About 3,000,000 kilometers C) About 30 million seconds D) About 30,000 kilometers E) About 10 trillion kilometers Answer: A 2) In a ten-billion to one scale model, the Sun and the Earth are about the size of A) a grape and a grain of sand. B) a basketball and a grape. C) a grapefruit and a grain of sand. D) a grapefruit and a grape. Answer: C 3) Jupiter is about 5 AU from the Sun. In a ten billion to one scale model, Jupiter is A) less than one meter from the Sun. B) about 75 meters from the Sun. C) about 15 meters from the Sun. D) about a kilometer from the Sun. Answer: B 4) Our textbook discusses the cosmic calendar, a model of the history of the universe scaled to a single year. The length of time represented by one month on this cosmic calendar is therefore: A) about one million years. B) about ten million years. C) about 1000 years. D) about one billion years. E) about ten billion years. Answer: D 5) Place the following items in order of actual physical size, from smallest to largest. A) Planets and stars are about the same size, solar system, galaxy. B) Planet, star, solar system, galaxy C) Star, planet, galaxy, solar system D) Planet, star, galaxy, solar system E) Star, planet, solar system, galaxy Answer: B 6) Rank the following 4 items by how long it takes for light to reach us from these objects, from shortest to longest. A) Sun, Pluto, the Andromeda Galaxy, center of the Milky Way B) The Andromeda Galaxy, the center of the Milky Way, Pluto, Sun C) Pluto, Sun, the Andromeda Galaxy, center of the Milky Way D) Pluto, Sun, center of Milky Way, the Andromeda Galaxy E) Sun, Pluto, center of the Milky Way, the Andromeda Galaxy Answer: E 7) Rank the following 3 items from nearest to farthest. Hint: the Orion Nebula is a cloud of gas in which young stars are being born within the Milky Way, about 1500 light-years away. A) Star in the center of the Milky Way, Orion Nebula, Alpha Centauri B) Star in the center of the Milky Way, Alpha Centauri, Orion Nebula C) Alpha Centauri, Orion Nebula, star in the center of the Milky Way Answer: C 8) One of the most fundamental discoveries about the Universe has been that it is expanding. "The universe is expanding" means A) our estimate for the size of the universe has increased over the last century. B) galaxies are growing with time. C) the cosmological horizon is growing with time. D) distances between most galaxies are getting larger. Answer: D 9) One of the main reasons the Hubble Space Telescope was built and launched was to measure how fast the universe is expanding. If the expansion turns out to be faster than we thought, our estimate for the age of the universe will be: A) unaffected. B) younger (less time between now and the Big Bang). C) older (more time between now and the Big Bang). Answer: B 10) Wendy measures a recession velocity for two distant galaxies, well outside our Local Group of galaxies. Galaxy A has a recession velocity of 35,000 km/s and Galaxy B has a recession velocity of 70,000 km/s. What can she say about the distances to those galaxies? A) She can't say anything about the distances to Galaxy A or B. B) Galaxy A is twice as far as Galaxy B. C) Galaxy A is four times as far as Galaxy B. D) Galaxy B is four times as far as Galaxy A. E) Galaxy B is twice as far as Galaxy A. Answer: E 11) You have taken a picture of a galaxy 1 billion light years away. That picture shows: A) a galaxy that is 1 billion years old. B) a galaxy that is 13 billion years old. C) a galaxy as it was 1 billion years ago. D) a galaxy that is 1 billion light years old. Answer: C 12) According to current scientific estimates, when did the Big Bang occur? A) About 10 billion years ago B) About 4.5 billion years ago C) About 14 billion years ago D) About 20 billion years ago E) About 65 million years ago Answer: C 13) How do scientists estimate how old the universe is? A) They look up the answer in a book. B) They measure the abundances of radioactive elements in meteorites, and use their half-lives to calculate the age. C) They measure how fast the Sun is losing energy, and how much energy it has to lose. D) They make a guess: no one really knows how old the universe is. E) They measure the speeds and distances of galaxies, and calculate the time it took for them to travel that distance. Answer: E 14) Which statements correctly locate the formation of the Earth and the appearance of the first humans on the cosmic calendar, which compresses the 14-billion year history of the universe into one "year," where "now" is exactly midnight, Dec 31? A) Earth forms in early September, life begins in November, and humans appear on Dec 15. B) Earth forms in January, life begins in September, and humans appear in October. C) Earth forms in early September, life begins in late September, humans appear a few hours before midnight, Dec 31. D) Earth forms in January, life begins in April, and humans appear in early December. Answer: C 15) Which object has aged the most since it emitted the light we see today? A) A star near the center of the Milky Way B) A star in the Andromeda Galaxy C) The Sun D) Pluto Answer: B 1.6 MasteringAstronomy Reading Quiz 1) Which of the following is not a general difference between a planet and a star? A) Planets are smaller than stars. B) Planets are dimmer than stars. C) All planets are made of rock and all stars are made of gas. D) Planets orbit stars, while stars orbit the center of the galaxy. Answer: C 2) Our solar system consists of ________. A) the Sun and all the objects that orbit it B) the Sun and the planets, and nothing else C) a few hundred billion stars, bound together by gravity D) the Sun and several nearby stars, as well as the planets and other objects that orbit these stars Answer: A 3) A typical galaxy is a ________. A) collection of a few hundred million to a trillion or more stars, bound together by gravity B) large, glowing ball of gas powered by nuclear energy C) nearby object orbiting a planet D) relatively small, icy object orbiting a star E) system consisting of one or a few stars orbited by planets, moons, and smaller objects Answer: A 4) Which of the following best describes what we mean by the universe? A) The sum total of all matter and energy. B) A vast collection of stars that number as many as the grains of sand on all the beaches on Earth. C) All the galaxies in all the superclusters. D) The universe is another name for our Milky Way Galaxy. Answer: A 5) What do astronomers mean by the Big Bang? A) The event that marked the beginning of the expansion of the universe B) A gigantic explosion that blew all the galaxies in the universe to smithereens C) The explosion of a massive star at the end of its life D) The event that marked the birth of our solar system Answer: A 6) What do we mean when we say that the universe is expanding? A) Everything in the universe is gradually growing in size. B) Within galaxies, average distances between star systems are increasing with time. C) The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing. D) Average distances between galaxies are increasing with time. Answer: D 7) Based on observations of the universal expansion, the age of the universe is about ________. A) 14,000 years B) 14 million years C) 14 billion years D) 14 trillion years Answer: C 8) A television advertisement claiming that a product is light-years ahead of its time does not make sense because ________. A) it doesn't specify the number of light-years B) it uses "light-years" to talk about time, but a light-year is a unit of distance C) a light-year is an astronomically large unit, so a product could not possibly be so advanced D) light-years can only be used to talk about light Answer: B 9) The term observable universe refers to ________. A) that portion of the universe that we have so far photographed through telescopes B) the portion of the universe that can be seen by the naked eye C) the portion of the universe that is not hidden from view by, for example, being below the horizon D) that portion of the universe that we can see in principle, given the current age of the universe Answer: D 10) On a scale in which the distance from Earth to the Sun is about 15 meters, the distance from Earth to the Moon is ________. A) small enough to fit within your hand B) about 1 meter C) about 5 meters D) about 30 meters Answer: A 11) On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun? A) 100 meters B) About the distance across 50 football fields C) About the distance across the state of Delaware D) About the distance across the United States Answer: D 12) The number of stars in the Milky Way Galaxy is approximately ________. A) a few hundred B) a few hundred thousand C) a few hundred billion D) a few hundred million Answer: C 13) An astronomical unit (AU) is ________. A) any very large unit, such as a light-year B) the average distance between Earth and the Sun C) the current distance between Earth and the Sun D) the average distance between any planet and the Sun Answer: B 14) What is the ecliptic plane? A) The plane of Earth's orbit around the Sun B) The plane of Earth's equator C) The plane of the Sun's equator D) The plane of the Milky Way Galaxy Answer: A 15) How long does it take the Earth to complete one orbit around the Sun? A) One year B) One day C) One month D) One week E) The time it takes Earth to orbit the Sun changes significantly from one orbit to the next. Answer: A 1.7 MasteringAstronomy Concept Quiz 1) Which of the following has your "cosmic address" in the correct order? A) You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe B) You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe C) You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe D) You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe E) You, Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe Answer: B 2) Using the ideas discussed in your textbook, in what sense are we "star stuff"? A) The overall chemical composition of our bodies is about the same as that of stars. B) Movie stars and other people are all made of the same stuff, so we all have the potential to be famous. C) Nearly every atom from which we are made was once inside of a star. D) We could not survive without light from our star, the Sun. Answer: C 3) How are galaxies important to our existence? A) Without galaxies, there could not have been a Big Bang. B) Without galaxies, the universe could not be expanding. C) Deep in their centers, galaxies created the elements from which we are made. D) Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist. Answer: D 4) When we look at an object that is 1,000 light-years away we see it ________. A) as it was 1,000 years ago B) as it was 1,000 light-years ago C) as it is right now, but it appears 1,000 times dimmer D) looking just the same as our ancestors would have seen it 1,000 years ago Answer: A 5) Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case ________. A) Galaxy 1 must be twice as big as Galaxy 2 B) we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2 C) we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2 D) Galaxy 2 must be twice as old as Galaxy 1 Answer: B 6) Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like? A) The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart. B) The planets are all much smaller than the Sun and are spread out evenly over a distance about the length of a large classroom. C) The planets are all much smaller than the Sun. Four planets are located within a few centimeters of the Sun, and four planets are located at distances ranging up to about a meter. D) The planets range in size from about the size of a marble to the size of a baseball. They are spread out over a region about the size of a football field. Answer: A 7) If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy? A) Several days B) Several weeks C) Several years D) Several thousand years Answer: D 8) The total number of stars in the observable universe is about ________. A) 100 billion B) the same as the number of grains of sand in a school sandbox C) the same as the number of grains of sand on all the beaches on Earth D) the same as the number of atoms that make up the Earth Answer: C 9) Where is our solar system located within the Milky Way Galaxy? A) Very near the center of the galaxy B) At the far edge of the galaxy's visible disk C) Roughly halfway between the center and the edge of the visible disk of the galaxy D) In the halo of the galaxy Answer: C 10) If we imagine the history of the universe compressed into one year, dinosaurs became extinct ________. A) about 6 months ago B) about 3 weeks ago C) yesterday morning D) about an hour ago Answer: C 11) Relative to the age of the universe, how old is our solar system? A) It is about 1% as old as the universe. B) It is between about 5% and 10% as old as the universe. C) It is about one-third the age of the universe. D) It is nearly the same age as the universe. Answer: C 12) How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects? A) Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth. B) Earth's rotation carries most people around the axis at about the speed of a commercial jet, and Earth's orbit carries us around the Sun at about the speed of a military jet. C) Earth's rotation carries most people around the axis at about the speed of a car on the freeway, and Earth's orbit carries us around the Sun at about the speed of a commercial jet. D) Earth's rotation carries most people around the axis at about the speed at which the Space Shuttle orbits Earth, and Earth's orbit carries us around the Sun at nearly the speed of light. Answer: A 13) Why do the patterns of the stars in our sky look the same from year to year? A) Because the stars in the constellations are so far away B) Because the stars in the constellations are not moving C) Because the stars in the constellations all move at the same speeds and in the same directions, so they don't change their relative positions D) Because the stars in the constellations move so slowly?typically about the speed of a snail?that their motions are not noticeable Answer: A 14) Astronomers infer that the universe is expanding because distant galaxies all appear to ________. A) be growing in size B) be moving away from us, with more distant ones moving faster C) be made mostly of dark matter D) rotate rapidly Answer: B 15) Which statement about motion in the universe is not true? A) The mysterious dark matter is the fastest-moving material in the universe. B) Some stars in the Milky Way Galaxy are moving toward us and others are moving away from us. C) Except for a few nearby galaxies, all other galaxies are moving away from us. D) Your speed of rotation around Earth's axis is faster if you live near the equator than if you live near the North Pole. Answer: A