Ring Galaxy AM 0644-741
from Hubble
From NASA’s Astronomy Picture of the Day
How could a galaxy
become shaped like a ring?
The rim of the blue
galaxy pictured on
the right is an immense ring-like structure 150,000 light years in
diameter composed of newly formed, extremely bright, massive stars.
That galaxy, AM 0644-741, is
known as a ring galaxy and
was caused by an immense galaxy collision.
When galaxies collide, they pass
through each other -- their individual stars rarely come into contact. The ring-like shape is the
result of the gravitational
disruption caused by an entire small
intruder galaxy passing through a large one.
When this happens,
interstellar gas and dust become
condensed, causing a wave of star
formation to move out from the impact point like a ripple across the
surface of a pond. The intruder galaxy is just outside of the frame taken by
the Hubble Space
Telescope.
This featured
image was taken to commemorate
the anniversary of Hubble's launch in
1990. Ring galaxy AM
0644-741 lies about 300 million light years away.
