Answer Happy

ASTRONOMY
Multiple Choice Portion 1. The color that a galaxy appears in an image could depend on ... a. how far away the galaxy is. b. what type of stars make up the galaxy. c. how much dust the galaxy has in it or in front of it. d. how fast the galaxy is moving away from us. all of the above e. a. c. 2. Which of the following is FALSE about dust in space? Dust scatters red light more easily than blue light. b. Dust can be detected via infrared emission. Dust was originally discovered in our Galaxy by comparing the properties of "open" star clusters at different distances. d. Dust is generally associated with gas and star formation. e. Dust can obscure the optical light from objects behind it. 3. A gravitational lens ... a. causes the light of background objects to bend around it. b. makes it possible to measure the total mass of the object doing the lensing. c. is a direct consequence of the Theory of General Relativity. d. can create arcs of light on the sky. all of the above e. 4. Which of the following is FALSE about 21-сm line emission? a. It results from the spin-flip transition of the electron in the hydrogen atom. b. It can be emitted from cold (T~100 K) gas. It arises from atomic hydrogen (HI) gas. d. It arises from an electron dropping from energy level n=2 to n=1. e. It can propagate long distances through a galaxy. c. a. 5. Which of the following is FALSE about the cosmic microwave background radiation? On average, it is a blackbody with an effective temperature of about 2.7 K. b. It has small temperature fluctuations of angular size ~1 deg on the sky. It is the relic of a hotter phase of the Universe. d. We detect it from the time when radiation fell out of equilibrium with matter. Its power spectrum suggests that the universe has positive (non-zero) curvature. c. e.