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Write true if the statement is true or false if the statement is false. _____ 1. There are billions of galaxies in the universe. _____ 6. Dwarf galaxies are often found near larger galaxies. _____ 2. A star cluster may contain one or more galaxies. _____ 7. Some galaxies contain over a trillion stars. _____ 3. Open star clusters contain more stars than globular star clusters. _____ 8. Our solar system is within one of the spiral arms of our galaxy. _____ 4. Galaxies are divided into types based on size. _____ 9. Our solar system orbits the central disk of our galaxy. _____ 5. Spiral galaxies are generally older than elliptical galaxies. _____ 10. From Earth, our galaxy looks like a giant spiral. Read this passage based on the text and answer the questions that follow. Types of Galaxies The biggest groups of stars in the universe are called galaxies. They may have a few million to more than a trillion stars. With the unaided eye, every star you can see is part of our own galaxy, the Milky Way Galaxy. All the other galaxies in the universe are extremely far away. The closest galaxy to our own, the Andromeda Galaxy, is 2.5 million light-years away. Galaxies are divided into three types according to their shape. The types are spiral, elliptical, and irregular galaxies. A spiral galaxy is a rotating disk of stars and dust. At the center of the disk is a dense bulge of matter. Several arms spiral out from the center. A spiral galaxy has a lot of gas and dust and many young stars. An elliptical galaxy is oval in shape. The smallest elliptical galaxies are called dwarf elliptical galaxies. Giant elliptical galaxies can contain over a trillion stars. Stars in elliptical galaxies are mainly old stars. Most elliptical galaxies contain very little gas and dust because the material has already formed into stars. An irregular galaxy is neither spiral nor elliptical. Most irregular galaxies have been deformed. This can occur either by the pull of a larger galaxy or by a collision with another galaxy. Questions 1. What are galaxies, and how do they range in size? 2. Contrast spiral and elliptical galaxies. 3. What are irregular galaxies, and how do they come about? Circle the letter of the correct choice. 1. Types of star clusters include a. open clusters. 5. Galaxies that do not have a clearly defined shape are called b. spiral clusters. a. deformed galaxies. c. elliptical clusters. b. irregular galaxies. d. all of the above c. dwarf galaxies. 2. Elliptical galaxies contain a. a lot of gas and dust. b. mainly young stars. c. mostly red or yellow stars. d. two of the above 3. Types of galaxies include a. spiral galaxies. b. cluster galaxies. d. open galaxies. 6. Scientists estimate that the Milky Way Galaxy contains about a. 40,000 stars. b. 400,000 stars. c. 40 million stars. d. 400 billion stars. 7. Some astronomers think that at the center of our galaxy there is a c. circular galaxies. a. neutron star. d. globular galaxies. b. supernova. 4. The stars in an open cluster are mostly a. old stars. c. red supergiant. d. black hole. b. young stars. c. reddish stars. d. two of the above Match each definition with the correct term. Definitions _____ 1. type of galaxy that is a rotating disk of stars and dust _____ 6. star cluster containing up to tens of thousands of stars _____ 2. star cluster containing up to a few thousand stars _____ 7. type of galaxy that is neither spiral nor elliptical in shape Terms _____ 3. type of galaxy that is oval in shape a. elliptical galaxy e. spiral galaxy _____ 4. group of stars that is smaller than a galaxy b. globular cluster f. star cluster c. irregular galaxy g. galaxy _____ 5. very large group of stars that are held together by gravity d. open cluster Fill in the blank with the appropriate term. 1. The stars in an open cluster are young stars that all formed from the same __________. 2. Every star you can see from Earth with the unaided eye is part of the __________ Galaxy. 3. Our own galaxy is the type of galaxy called a(n) __________ galaxy. 4. The major galaxy closest to our own is the __________ Galaxy. 5. A spiral galaxy has a rotating disk of stars and dust with several __________ projecting out from the center. 6. Most __________ galaxies have been deformed by gravity or a collision with another galaxy. 7. Globular clusters have a definite __________ shape. Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences. Describe our own galaxy, and explain why it looks different to us than all other galaxies?