Sgr A is believed to be the center of the Milky Way galaxy because I. It lies in the general ...

Sgr A is believed to be the center of the Milky Way galaxy because I. It lies in the general direction of the center of the galaxy based on observations of globular clusters in the plane of the Milky Way. II. Long wavelength dust penetrating images show it to be a region crowded with stars III. Orbits of stars around it indicate a mass several million times that of the Sun within a volume a few light hours in size IV. Radio observations show it is a concentrated source at the center of swirling clouds of gas
 
  a. I & II only
  b. II & III only
  c. I & IV only
  d. II & IV only
  e. All of I, II, III, & IV

Question 2

Helioseismology is the study of the differential rotation and magnetic field of the sun.
 
  Indicate whether the statement is true or false

Question 3

Radio maps of the spiral arms of our galaxy
 
  a. reveal that our galaxy is a grand design spiral.
  b. map the location of Hot O and B stars by the radio radiation they emit.
  c. reveal that the spiral arms are winding up and growing closer together.
  d. reveal that the sun is currently located in the center of a spiral arm.
  e. map the location of dense neutral hydrogen clouds.