Our World Started With a Collision
Even though a dwarf galaxy clear across the Milky Way looks to be a mouse, it may have once been a bear that slashed through the Milky Way and created the galaxy’s spiral arms. What does all this mean?
Astronomer Curtis Struck thinks the Sagittarius Dwarf Elliptical Galaxy collided with the Milky Way, creating the galaxy’s spiral arms, its central bar structure and the flaring at its outer disk. Along the way, the dwarf galaxy’s stars were scattered and the galaxy shrunk to an object that’s so small and unimpressive it’s hard to see. Maybe the evolution of our Milky Way galaxy did include collisions and wasn’t as peaceful as astronomers had thought.