Observations of Colliding Galaxies:
Snapshots in Time

Problem: Galaxy collisions take hundreds of millions or even billions of years to occur -- we can't watch a collision happen.

When we observe interacting galaxies we see fragmented, differing pieces of a larger evolutionary process.

(images courtesy John Hibbard, National Radio Astronomy Observatory)

We want to understand how these "snapshots" relate, and explore galaxy collisions in an evolutionary context.

• What happens when galaxies collide?
• How do interactions trigger starburst activity?
• Can mergers make elliptical galaxies?
• What about smaller accretion events?

Next: Computer Models of Colliding Galaxies