Exam 3 Spring 2000 Practice Test 1

Many of these questions will appear in their original form, as given here, but most will not. You are forewarned not to simply memorize the answers.

1) How does the interstellar medium obscure our view of most of the galaxy? 2) Harlow Shapley concluded that the Sun was not in the center of the Milky Way Galaxy by 3) Where are most heavy elements made? 4) What produces the 21-cm line that we use to map out the Milky Way Galaxy? 5) Compared with our Sun, most stars in the halo are 6) What kinds of objects lie in the halo of our galaxy? 7) What kinds of objects lie in the disk of our galaxy? 8) Compared with stars in the disk, orbits of stars in the halo 9) Why do we believe 90% of the mass of the Milky Way is in the form of dark matter? 10) Which constellation lies in the direction toward the galactic center? 11) How do we learn about what is going on in the center of our own galaxy (the Milky Way)? 12) What evidence supports the theory that there is a black hole at the center of our galaxy? 13) Suppose that we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest? 14) Which of the following types of galaxies are most spherical in shape? 15) Which of the following types of galaxies are reddest in color? 16) Which types of galaxies have a clearly defined disk component? 17) The disk component of a spiral galaxy includes which of the following parts? 18) What is the major difference between an elliptical galaxy and a spiral galaxy? 19) Most large galaxies in the universe are 20) Which of the following types of galaxies are most commonly found in large clusters? 21) Why are Cepheid variables important? 22) What is a standard candle? 23) How was Edwin Hubble able to use his discovery of a Cepheid in Andromeda to prove that the "spiral nebulae" were actually entire galaxies? 24) What is Hubble's law? 25) What is the primary practical difficulty that limits the use of Hubble's law for measuring distances? 26) What is the most accurate way to determine the distance to a nearby star? 27) What is the most accurate way to determine the distance to a nearby galaxy? 28) Dr. X believes that the Hubble constant is 55 km/s/Mpc. Dr. Y believes it is 80 km/s/Mpc. Which statement below automatically follows? 29) Dr. Smith believes that the Hubble constant is 70 km/s/Mpc. Dr. Jones believes it is 50 km/s/Mpc. Which statement below automatically follows? 30) Recall that Hubble's law is written v = Hod, where v is the recession velocity of a galaxy located a distance d away from us, and Ho is Hubble's constant. Suppose Ho = 70 km/s/Mpc. How fast would a galaxy located 500 megaparsecs distant be receding from us? 31) How do observations of distant galaxies help us learn about galaxy evolution? 32) What is a quasar? 33) The most active galactic nuclei are usually found at large distances from us; relatively few nearby galaxies have active galactic nuclei. What does this imply? 34) Why should galaxy collisions have been more common in the past than they are today? 35) What evidence supports the idea that a collision between two spiral galaxies might lead to the creation of a single elliptical galaxy? 36) Which of the following is not a piece of evidence supporting the conclusion that active galactic nuclei are powered by accretion disks around massive black holes? 37) How is the energy that powers radio galaxies, quasars, and other active galactic nuclei produced? 38) What evidence suggests that the Milky Way contains dark matter? 39) Gravitational lensing occurs when 40) Why isn't space expanding within systems such as our solar system or the Milky Way? 41) What are peculiar velocities? 42) Which of the following has your "address" in the correct order? 43) What do we mean when we say that the universe is expanding? 44) The Earth is made mostly of metals and rocks. Where did this material come from? 45) Why does Carl Sagan say that we are star stuff? 46) How are galaxies important to our existence? 47) Suppose we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest? 48) The age of the universe is 49) Which of the following statements does not use the term light-year in an appropriate way? 50) About where is our solar system located within the Milky Way Galaxy? 51) 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? 52) 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 53) By studying distant galaxies in the 1920s, Hubble made the following important discovery that led us to conclude that the universe is expanding: 54) 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? 1) B 2) C 3) A 4) A 5) E 6) A 7) E 8) A 9) D 10) C 11) B 12) B 13) D 14) D 15) C 16) E 17) B 18) B 19) D 20) C 21) D 22) B 23) D 24) B 25) A 26) E 27) D 28) A 29) A 30) C 31) E 32) A 33) B 34) A 35) E 36) B 37) D 38) D 39) D 40) D 41) B 42) E 43) D 44) B 45) C 46) E 47) B 48) E 49) A 50) A 51) D 52) D 53) B 54) D