1 A) A spiral-shaped region of nebulosity. B) A pale band of light scattered with stars that stretches across the sky. C) A uniform scattering of stars throughout the sky. D) The Milky Way is not visible from Earth without a telescope. 2 A) 25 light years. B) 25,000 km C) 100,000 light years. D) 10 million light years 3 A) 1 million solar masses B) 1 billion solar masses. C) 1011 solar masses. D) 1020 solar masses. 4 A) Open star clusters. B) Globular star clusters. C) Interstellar gas clouds. D) Spiral arms. 5 A) They are old. B) They are frequently blue. C) They are high heavy element content. D) They are found in the disk. 6 A) we can see it in dark clouds and clouds that absorb light. B) the matter creates narrow absorption lines in the spectra of some stars. C) we can detect radio waves coming from atoms and molecules in the cold gas. D) All of the above. 7 A) We can observe the tiny particles with the Hubble Space Telescope. B) Dust emits x-rays. C) Dust obscures and reddens starlight. D) Interstellar matter is composed only of hydrogen gas. 8 A) Emission nebulas give off their own light; reflection nebulas reflect the light of nearby stars. B) Generally, emission nebulas appear red, and reflection nebulas look blue. C) In emission nebulas, gas atoms emit light; in reflection nebulas, dust particles reflect light. D) All of the above. 9 A) A part of the region of the Solar System where it is too dangerous to send spacecraft. B) A quadrant of the Galaxy where no galaxies exist. C) A part of the sky in which astronomers cannot observe due to bright emission from interstellar dust. D) The region of the sky where no galaxies are seen due to obscuring dust in the Milky Way. 10 A) HII regions B) globular clusters C) Pop II stars D) alien tattoos 11 A) observing magnetic fields in the Solar System. B) using radar. C) sending unmanned space missions to the center of the galaxy. D) observing its gravitational attraction on matter in and near it. 12 A) Theory predicts that there should be more black holes than we've so far detected. B) The galaxy's gravity seems too big for the mass astronomers can see. C) Due to its large size, the light from stars on the other side of the Milky Way has not reached us yet. D) Astronomers have detected neutrinos from unseen sources. 13 A) a region 10,000 light years across containing no stars B) a 10,000 solar mass star whose luminosity is 100 million solar luminosities C) a black hole the mass of a few million Suns D) a sphere of ice 1 million miles in diameter 14 A) It is a way of describing the formation of galactic spiral arms. B) It is a model who puts on a show at astronomy meetings. C) It is a description of how light propagates. D) It is a theory of the origin of the Universe.
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