6. Which of the following are steps toward measuring thedistance to stars using spectroscopic parallax? a) Measure thestar’s spectral type and calculate the mass. b) Measure the star’sspectal type and the apparent brightness, i.e., the flux. c)Measure the star’s rotation period and the number of starspots. d)Measure the star’s orbital period if it is in a binary and use thatto estimate the spectral types of both stars. e) Measure the slightwobble in the star’s motion caused by planets orbiting thestar.

What single piece of information revolutionized ourunderstanding of “spiral nebulae”, such as the spiral nebula inAndromeda, to show that they are spiral galaxies full of stars? a)We measured their average temperature. b) We placed them on theHertzsprung-Russel diagram. c) We measured their distance. d) Wemeasured their parallax. e) We measured their orbital periods

2. Which statement about our Galaxy, the Milky Way, is true? a)The halo contains no O and B stars while the disk contains stars ofall spectral types. b) The halo contains only young stars while thedisk contains stars of all ages. c) The halo contains hundreds orperhaps thousands of “super-massive” black holes. d) Our Sun islocated a few light years from the center of our Galaxy. e) TheMilky Way is unique in having no smaller galaxies orbiting aroundit.