Q: From our perspective in the Milky Way, we see the Andromeda Galaxy almost — but not quite — edge on. At what angle do the inhabitants of Andromeda see our galaxy?
Ralph Johnson
West Long Branch, New Jersey
A: The inclination angle of a galaxy is defined as the orientation of its stellar disk relative to the line of sight of an observer. A galaxy with an inclination angle of 90° is viewed edge-on, whereas a galaxy with an inclination angle of 0° is viewed face-on. Andr