Explanation:
On the right, surrounded by blue spiral arms, is spiral galaxy
M81.
On the left, marked by red gas and dust clouds, is irregular galaxy
M82.
This stunning vista shows these two mammoth galaxies locked in
gravitational combat, as they have been for the past billion years.
The gravity from each galaxy
dramatically affects the
other during each hundred million-year pass.
Last go-round, M82's gravity likely raised
density waves rippling around
M81,
resulting in the richness of
M81's
spiral arms.
But M81 left
M82 with
violent star forming regions and
colliding gas clouds so energetic the galaxy
glows
in X-rays.
In a few billion years only one galaxy
will remain.
