For a long time, scientists thought that galaxies were quiet, stable citizens of the universe.
On the contrary, however, many galaxies engage in great, even violent, activity.
Seyfert galaxies, for instance, emit 100 times the electromagnetic waves of ordinary galaxies.
Active galaxies are known to collide and produce massive nuclear explosions, sending jet streams of matter stemming from their centers.
When two galaxies get too close to each other in their orbits, the larger galaxy, or cannibal galaxy, will frequently consume the smaller.
Evidence of this cannibalism is seen in the form of a large galaxy exhibiting more than one nucleus.
The nuclei are left over from the devoured galaxy.
A galaxy named Abell 407, for instance, has nine nuclei from galaxies it has swallowed.