While imaging the Andromeda Galaxy, the Spitzer Space Telescope uncoverd a never-before-seen hole, the result of a collision with a nearby dwarf galaxy, in the Andromeda Galaxy.

While imaging the Andromeda Galaxy, the Spitzer Space Telescope uncoverd a never-before-seen hole, the result of a collision with a nearby dwarf galaxy, in the Andromeda Galaxy.
Understanding our Galaxy through GAIA Mission with @einionyn & @georgeseabroke. More at #365DaysOfAstro
Nowadays, outer part of our Galaxy spins faster. But back in the early Universe it would have rotated much more slowly.