Astronomy Test Questions 16-Life Essay Study Guide 16 - One way astronomers deduce that the Milky Way has a disklike shape is that they see... - ANSWERSthe great majority of stars in a band that encircles us. 16 - Select all that are correct. Most of t

16 - One way astronomers deduce that the Milky Way has a disklike shape is that they see... - ANSWERSthe great majority of stars in a band that encircles us. 16 - Select all that are correct. Most of the stars in the Milky Way... - ANSWERS-are not visible to the naked eye -have the same or less mass than the star. 16 - a young blue star moving along a circular orbit in the disk is a... - ANSWERSPop I Star 16 - Globular clusters have mainly ___ stars. - ANSWERSPop II 16 - Astronomers know that interstellar matter exists because (select all that apply)... - ANSWERS-they can see it in dark clouds and clouds that absorb light -the matter creates narrow absorption lines in the spectra of some stars, they can detect radio waves coming from atoms and molecules in the cold gas 16 - What kind of interstellar cloud generally has a bluish color? - ANSWERSReflection Nebula 16 - Astronomers think the Milky Way has spiral arms because (select all that are correct) - ANSWERS-radio maps show that gas clouds are distributed in the disk with a spiral pattern -young star clusters, HII regions, and associations outline spiral arms, -other galaxies that also have gas and dust have spiral arms 16 - The modified form of Kepler's third law allows astronomers to determine the Milky Way's... - ANSWERSmass 16 - Astronomers think there is a massive black hole at the center of the Galaxy because (select all that are correct)... - ANSWERS-other galaxies have massive black holes at their centers -they have plotted the orbits of stars and calculated a large, dark mass is present there 16 - Faint streams of stars in the Milky Way's halo are interpreted as evidence that... - ANSWERSthe Milky Way is stripping material from smaller dwarf galaxies 17 - A large galaxy contains mostly old (Pop II) stars spread smoothly throughout its volume, but it ahs little dust or gas. What type of galaxy is it most likely to bed? (Select all are possible, even though there is 1) - ANSWERSE A galaxy's spectrum has a redshift of 14,000 kilometers per second. If the Hubble constant is 70 kilometers per second per megaparsec, how far away from Earth is the galaxy? - ANSWERS200 megaparsecs 17 - Why might a galaxy a galaxy such as M31 (Andromeda) have a blueshift instead of a redshift? - ANSWERSThe effect of its orbital or local motion is bigger than the effect of the universe's expansion. 17 - Which of the following would be a profitable result of a collision between two galaxies? - ANSWERSFormation of a ring galaxy 17 - A spiral galaxy has a small bright central region, and its spectrum shows that it contains hot, rapidly moving gas. It is most likely a ___ galaxy. - ANSWERSSeyfert 17 - The Local Group (select all that are correct)... - ANSWERS-contains about 40 member galaxies -is one of the smaller galaxy clusters -is the galaxy cluster to which the Milky Way belongs 17 - The largest clusters probably contain many elliptical galaxies because... - ANSWERSgas is stripped out of galaxies during collisions 17 - Galaxy clusters often contain ___ as much mass in hot gas as in stars in their member galaxies... - ANSWERS10 17 - Most of the mass of a galaxy is contained in its... - ANSWERSdark matter halo 17 - The ratio of dark matter to visible matter in a typical elliptical or spiral galaxy is about... - ANSWERS10:1 18 - From what evidence do astronomers deduce that the Universe is expanding? - ANSWERSThey see a redshift in the spectral lines of distant galaxies. 18 - If Hubble's constant were half of the value we think it is, the Universe would be ___ as we think it is. - ANSWERS2x as old 18 - What is meant by the cosmic microwave background? - ANSWERSIt is radiation created in the early Universe 18 - Which of the following statements about the first few minutes of the Big Bang is true? - ANSWERSHydrogen fused into Helium 18 - For most of the time since the beginning of the Universe, conditions were... - ANSWERSnot very different from today. 18 - Which of the following are explained by a brief period of inflation? (Select all that apply) - ANSWERS-the high uniformity of the cosmic microwave background in multiple direction -the fact that the Universe appears flat 18 - If the density of the Universe were greater than the critical density ad the Universe contained no dark energy, then... - ANSWERSthe Universe would eventually collapse 18 - Dark energy (select all that apply)... - ANSWERS-is represented in cosmological equations by the cosmological constant -acts against gravity -causes space to expand ever faster -is distributed evenly through space 18 - Current measurements suggest the Universe is composed of about... - ANSWERS68% dark energy 27% dark matter 5% regular matter Evidence that life on earth is very ancient comes from... - ANSWERSfossil bacteria in rocks more than 3 billion years old The Miller-Urey experiment demonstrated that... - ANSWERSconditions on the early Earth were suitable for the creation of many of the complex organic molecules found in living things. High-mass stars probably do not harbor intelligent life because... - ANSWERStheir lives are too short for complex life to evolve. The Drake equation attempts to determine.... - ANSWERSthe number of technically advanced civilizations. Those who argue we are the only civilization in the Milky Way might support their argument by claiming that (select all that apply)... - ANSWERS-otherwise we should have been colonized by another more advanced civilization -otherwise we should be inundated by radio signals from other civilizations -just because life started early on Earth doesn't mean it is easy to start life-we might be an exception A planet on which life forms create an atmosphere that makes the planet more hospitable for life is an example of... - ANSWERSthe Gaia hypothesis According to the anthropic principle... - ANSWERSthe Universe could not differ radically from its present properties or we would not be here to observe it.