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1 | | What are the three main types of galaxies? |
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2 | | How do the basic galaxy types differ in shape, stellar content, and interstellar matter? |
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3 | | Why is it not surprising that elliptical galaxies contain only old stars? |
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4 | | Which of the basic galaxy types has the smallest proportion of Pop I stars? |
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5 | | What happens to the stars when two galaxies collide? |
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6 | | Why are galaxy collisions of interest? |
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7 | | How do astronomers measure the distance to nearby galaxies? |
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8 | | What is the Hubble law? |
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9 | | Why are astronomers uncertain about the value of the Hubble constant? |
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10 | | How do astronomers measure the mass of a galaxy? |
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11 | | What is meant by dark matter? |
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12 | | What are the three main types of active galaxies? |
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13 | | Make a sketch of a radio galaxy illustrating its structure and where its radio emission comes from. Why do astronomers call these objects “radio” galaxies? |
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14 | | What process generates the radio emission in radio galaxies? |
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15 | | What is a Seyfert galaxy? |
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16 | | What is a quasar? |
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17 | | Why do some astronomers think that quasars are very distant? |
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18 | | How is it known that active galaxies have small core regions? |
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19 | | What mechanism has been suggested to power active galaxies? |
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20 | | How might a large black hole form in a galaxy’s core? |
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21 | | What is a gravitational lens? |
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22 | | What are some differences between rich and poor clusters? |
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23 | | What is the Local Group? |
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24 | | What is the Local Supercluster? |
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25 | | What is a void? |
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