These two galaxies are at the heart of the Virgo Cluster,
about 50 million light years from earth. 4438 (on the right)
seems to have had its structure seriously challenged by
something. One theory is that it has absorbed a smaller galaxy,
which is not yet completely assimilated. A more common theory is
that 100 million years ago, these two galaxies got too close to
one another; the gravity from 4436 stretched out material from
4438, which hasn't yet managed to pull itself back together.

Image data:
Camera: DSI-Color
Exposure: 1 minute x 70
Telescope: 10" Schmidt-Newtonian