The Immense Size of the Milky Way.

A recent study summarizes the various methods used to determine the mass of the Milky Way, including measuring the motion of stars, globular clusters, satellite galaxies, tidal plumes of dwarf galaxies, and stars leaving our galaxy. The team took a statistical average of these methods and determined the best value for the mass of our galaxy to be a trillion solar masses, give or take a few hundred billion solar masses.