Name Date Period 30 GALAXIES AND THE UNIVERSE SECTION 30.1 The Milky Way Galaxy In your textbook, read about discovering the Milky Way. (20 points) For each item in Column A, write the letter of the matching item in Column B. Column A 1. Stars in the giant branch of the H-R diagram that pulsate in brightness because of the expansion and contraction of their layers 2. Stars that have periods of pulsations between 1.5 hours and 1.2 days, and on average, have the same luminosity 165 points Column B a. Cepheid variables b. luminosity c. RR Lyrae variables d. Sagittarius e. variable stars 3. Stars with pulsation periods between 1 day and more than 100 days 4. By measuring a star s period of pulsation, astronomers can determine this 5. Direction of the center of the Milky Way is toward this constellation In your textbook, read about the shape of the Milky Way. For each statement below, write correct or not correct. If the statement is not correct, use proofreading marks to make it correct. 6. Radio waves are used to map the Milky Way because they can penetrate the interstellar gas and dust without being scattered or absorbed. 7. Measurements of star luminosity at different distances provide a hint of the Milky Way s spiral arms. 8. Around the Milky Way s nuclear bulge and disk is the halo, where the globular clusters are located. 9. Five major spiral arms and a few minor arms were identified in the Milky Way.. 10. The Sun is located in the Milky Way s minor arm Orion at a distance of 26,000 ly from the galactic center. 11. In its 5-billion-year life, the Sun has orbited the galaxy approximately 100 times. In your textbook, read about the mass of the Milky Way. Use each of the terms below just once to complete the passage. 2.6 million 100 billion dark matter galaxy stellar remnants halo supermassive black hole The mass located within the circle of the Sun s orbit through the galaxy is about (12) times the mass of the Sun. Because the Sun is of average mass, astronomers have concluded there are about 100 billion stars within the disk of the (13). Astronomers have found evidence that much more mass exists in the outer galaxy. Evidence indicates that as much as 90 percent of the galaxy s mass is contained in the (14). This mass is not observed in the form of normal stars, and astronomers hypothesize that some of this unseen matter is in the form of dim (15), such as white dwarfs, neutron stars, and black holes. The remainder of this mass, usually called (16), is a mystery. Studies of the motion of stars that orbit close to Sagittarius A indicate that this area has about (17) times the mass of the Sun, but is smaller than our solar system. Astronomers believe that Sagittarius A is a (18) that glows brightly because of the hot gas surrounding it and spiraling into it. In your textbook, read about the formation and evolution of the Milky Way and maintaining spiral arms. 19. What two theories explain how the spiral arms are maintained? What two theories explain how the spiral arms are maintained? Page 1
Name Date Period SECTION 30.2 Other Galaxies in the Universe In your textbook, read about discovering other galaxies. (8 points) Circle the letter of the choice that best completes the statement or answers the question. 1. The question about other objects existing in the sky was answered by Edwin Hubble in 1924. What did he discover in the Great Nebula in the Andromeda constellation? a. Cepheid variable stars c. RR Lyrae variables b. a supernova d. a black hole 2. Disklike galaxies with spiral arms are divided into which of the following two subclasses? a. normal spirals and flat spirals c. flat spirals and barred spirals b. normal spirals and barred spirals d. loose spirals and flat spirals 3. Galaxies that are not flattened into disks and do not have spiral arms are called a. dwarf galaxies. c. elliptical galaxies. b. barred elliptical galaxies. d. nebular galaxies. 4. Galaxies that do not fit into the spiral or elliptical classifications are called a. dwarf galaxies. c. barred galaxies. b. Hubble galaxies. d. irregular galaxies. In your textbook, read about the expanding universe, active galaxies, and quasars. For each item, write the word from the box Hubble constant _ 5. Feature in the spectra quasars of galaxies that indicates that radio galaxies they are moving away from redshift Earth _ 6. _ 7. _ 8. About 70 km per second per megaparsec Extremely bright galaxies that are often giant elliptical galaxies emitting as much or more energy in radio wavelengths than in wavelengths of visible light Starlike objects with emission lines in their spectra SECTION 28.1 Solar System Overview In your textbook, read about collapsing interstellar clouds and Sun and planet formation. For each item, write the word from the box _ 1. Gas and dust from which stars and planets form _ 2. Force that pulls matter together _ 3. Solid bodies hundreds of kilometers in diameter that merged to form the planets _ 4. Believed to be the first large planet to develop _ 5. Main element in early interstellar clouds _ 6. Lacking in satellites because of proximity to the Sun Sequence the events of a collapsing interstellar cloud. The cloud becomes denser at the center. Rotation slows and the cloud flattens The cloud spins faster and faster. The cloud becomes a rotating disk. The collapse of the cloud begins to accelerate. 25 points inner planets hydrogen planetesimals gravity interstellar cloud Jupiter Describe the nebular theory of solar system formation and the evidence supporting it. (6 points) Page 2
Name Date Period In your textbook, read about the Big Bang model. Answers each question. 14. Name the three possible outcomes for the universe. SECTION 30.3 Cosmology (30 points) In your textbook, read about models of the universe. Use each of the terms below just once to complete the passage. The study of the universe, including its current nature, its origin, and its evolution is called (1). The fact that the universe is (2) _ implies that it had a beginning. The theory that the universe began as a point and has been expanding ever since is called the lower (3) theory. The (4) expanding of the universe determines the outcome Wilkinson Microwave Anistropy Probe cosmic background radiation of the Big Bang. In a(n) (5) universe the expansion will never stop. In a(n) (6) universe the expansion stops and becomes a contraction. According to the more accepted theory, the Big Bang Theory, if the universe began in a highly (7) state, it would have been very hot, and the high temperatures would have filled it with (8). As the universe expanded and cooled, the radiation would have been shifted to (9) energies and longer wavelengths. In 1965, scientists discovered a persistent (10) in their radio antenna. The noise was caused by weak radiation called the (11) It appeared to come from all directions in space and corresponded to an emitting object having a temperature of about (12), which is close to the temperature predicted by the Big Bang theory. An orbiting observatory called the (13), launched in 2001, mapped the radiation in detail. open closed 2.725 K compressed cosmology background noise radiation density Big Bang 15. Describe the premise of the rate of expansion that these three possible outcomes for the universe are based on? 16. Evidence suggests that the universe contains a great amount of 17. The universe began as a point and has been expanding ever since is called the 18. When the rate of expansion of the universe is known, it is possible to calculate the 19. Based on the best value for H that has been calculated, the age of the universe is hypothesized to be about 20. Illustrate a star moving away from you and another star moving toward you. Show how waves are shortened and elongated. Label redshift and blueshift. Page 3
Name Date Period GALAXIES AND THE UNIVERSE Reviewing Vocabulary (35 points) For each item in Column A, write the letter of the matching item in Column B. 1. Study of the universe Column A 2. Core of a galaxy in which highly energetic objects or activities are located 3. Gigantic formation of clusters of galaxies hundreds of millions of light-years in size 4. A value of approximately 70 kilometers per second per megaparsec Column B a. closed universe b. cosmology c. Big Bang theory d. cosmic background radiation e. open universe f. Hubble constant g. active galactic nucleus h. superclusters 5. States that the universe began as a point and has been expanding ever since 6. Proposes that the universe will never stop expanding 7. Persistent noise discovered in 1965 that is caused by weak radiation from all directions in space 8. Model that says the universe will stop expanding and begin to contract 9. Describe the big bang theory and the two important pieces of evidence that supports this theory. Understanding Main Ideas In the space at the left, write correct if the statement is correct; if the statement is not correct, change the italicized word or phrase to make it correct. 1. The Milky Way is a spiral galaxy. 2. Studies provide evidence that there is a great amount of unseen matter called dark matter composed of dim stellar remnants that have no mass. 3. Edwin Hubble measured the redshifts and distances of many galaxies and found that the redshift of a galaxy depends on its distance from Earth. 4. Cosmic background radiation provides information about conditions now in the expansion of the universe. 5. One way to estimate the fate of the universe is to measure how much acceleration has occurred in its expansion. 6. A key goal of the Fermilab is to gather data that would help to pinpoint the value for H, the Hubble constant. 7. Heavy elements found on Earth are formed in stars. 8. Our sun produces Helium by fusion of Lithium atoms. 9. According to the redshift of spectral analysis starlight, all of the galaxies are moving toward each other. 10. The fact that there are elements larger than Iron on Earth provides evidence that a Supernova once happened in this section of the Universe billions of years ago. 11. Radioactive decay suggests that the earth and solar system are 4.6 billion years old. Page 4
Name Date Period Applying Scientific Methods Answer the following questions. (15 points) 1. What is a black hole? 2. In the chart, what unit of measurement is used to show black hole mass? 3. What do each of the three columns in the chart show? 4. What is the mass of the largest black hole on the chart? What is the mass of the smallest? 5. According to the article, what did astronomers once believe about black holes? Black Holes: One Size Does Not Fit All Astronomers are concluding that monstrous black holes were not born that big, as once believed, but instead grew on a diet of gas and stars controlled by their host galaxies in the beginning years of the universe. An initial look at 30 galaxies indicates that black holes do not precede a galaxy s birth, but instead evolve with the galaxy by trapping an amazingly exact percentage (0.2) of the mass of the stars and gas in a galaxy. Black holes in the centers of giant galaxies some more than one billion solar masses had enough infalling gas to once blaze as quasars. The final mass of a black hole is not primordial, but instead is determined during the galaxy formation process. This shows that there is a close relationship between the black hole mass and the stars that comprise an elliptical galaxy or central bulge stars of a spiral galaxy. In most cases, the black holes not only bulked up through the accretion of gas, but also through mergers of galaxies in which pairs of black holes combined. The Hubble Space Telescope precisely measures the speed of gas and stars around a black hole. This measurement provides clues for the existence of a black hole. Astronomers determine the mass of each black hole by measuring the motion of stars swirling around it. The closer a star is to the black hole, the faster is its velocity. 6. What have astronomers learned from the more than 30 black holes they now study? 7. Other than accruing gas and stars, how else can black holes increase in size? 8. How does the Hubble Space Telescope measure black holes if black holes cannot be seen? Page 5
Life Cycle of Stars Big Bang Theory Created by Puzzlemaker at DiscoveryEducation.com Down 1. expansion of the universe stops and begins to contract back to original point of origin 2. when C is fused and energy production ends expels outer layers 3. Unknown component that makes up about 23% of all matter in the universe 4. expansion of the universe slows to a halt, but never contracts 6. star that is fusing H into He 9. stable final stage of a star made of C 11. extremely dense final stage of a star 17. used as evidence for the Big Bang Theory 18. expansion of the universe never stops 20 points Across 5. study of the universe, its nature, origin, and evolution 7. spinning neutron star that pulsates a pattern of light 8. an explosion that blows away the outer portion of a star fusing together the heavier elements 9. probe launched by NASA to map cosmic background radiation 10. massive star that fuses elements up to Ni into layers Across 12. cloud of interstellar gas and dust which collapses on itself as a result of gravity 13. end result of massive star with so much pressure pulling on gravity that light cannot escape 14. star that has burned all H into He and now begins fusing He into larger elements 15. theory that the universe began as a point and has been expanding ever since 16. hot condensed center where fusion may begin Name Date Period Page 6