Astronomers claim that the Milky Way is not as massive as we thought, especially when compared to our neighbor galaxy, Andromeda
Various methods that astronomers have used in the past to weigh galaxies have shown the Milky Way to be the heaviest member of our Local Group.
The Local Group is your home (broadly speaking of course). It is a collection of 35+ diverse galaxies that are gravitationally bound to each other. The standouts of this group (in terms of mass and beauty) are the Andromeda Galaxy and our very own Milky way.