This image of PGC 10922, an example of a lenticular galaxy — a galaxy type that lies on the border between ellipticals & spirals. Seen face-on, this image shows the disc & tightly-wound spiral structures of dark dust encircling the bright centre of the galaxy. There is also a remarkable outer halo of faint wide arcs or shells extending outwards. These are likely to have been formed by a gravitational encounter or even a merger with another galaxy.
A beautiful new image of two colliding galaxies has been released by NASA's Great Observatories. The Antennae galaxies, located about 62 million light-years from Earth, are shown in this composite image from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold and brown), and the Spitzer Space Telescope (red).
NGC 474 is an elliptical galaxy in the constellation Pisces. This large galaxy is known to possess tidal tails, although their origins remain unknown. These tidal tails may be related to debris left over from absorbing numerous small galaxies in the past billion years. Or the shells may be like ripples in a pond, where the ongoing collision with the spiral galaxy just above NGC 474 is causing density waves to ripple though it.