How do we detect mass that is not visible?
Matter orbiting the outer parts of galaxies shows there is mass not included in the stars
- See motion by “blue” and “red” shifts of spectral lines
How can we find Mass of the Galaxy? (Exercise)
Work of Vera Rubin (Student of George Gamov) in the 1960’s
Concludes there must be a “halo” of mass. What is it??
Object orbiting a galaxy – moving toward us