A different chemical composition 35. Io Europa Ganymede Callisto 36. The following are True of False. Shapley found the distance to the center of the galaxy by studying the distance to open clusters. True False 38.
Spiral tracers tend to be old luminous stars.
True False 39. When a large galaxy collides with a small galaxy, the smaller galaxy may be pulled apart by tidal forces. True False 40. True False 41. The rapid fluctuations of quasars show that the objects must be very small.