Explanation:
Will our Milky Way Galaxy collide one day with its larger neighbor, the Andromeda Galaxy?
Most likely, yes.
Careful plotting of slight displacements of M31's stars relative to background galaxies on recent
Hubble Space Telescope images indicate that the center of M31 could be on a direct
collision course with the center of our home galaxy.
Still, the errors in sideways velocity appear sufficiently large to admit a
good chance that the central parts of the two galaxies will miss, slightly, but will become
close enough for their outer halos to become
gravitationally entangled.
Once that happens, the two galaxies will become bound,
dance around, and
eventually merge to
become one large
elliptical galaxy --
over the next few billion years.
Pictured above is an artist's illustration of the sky of a world in the distant future when the central parts of each galaxy begin to destroy each other.
The exact future of our Milky Way and the entire surrounding
Local Group of Galaxies
is likely to remain an active topic of research for years to come.
Partial Lunar Eclipse Galleries:
Today's Lunar Eclipse and a
Collection of Past APOD Lunar Eclipse Images