The Cartwheel Galaxy is part of galaxy group about 500 million light years away in the constellation Sculptor. The galaxy displays an impressive ring-like structure 100,000 light years across, illuminated by young blue super giants. This shape is the result of the gravitational disruption caused by a small intruder galaxy passing directly through the larger large one, compressing the interstellar gas and dust, and causing a wave of star formation to move out from the impact point like a ripple across the surface of a pond.
High resolution radio observations reveals a trail of neutral hydrogen leading to the small galaxy in the top middle of the image, which is therefore assumed to be the intruder.

OPTICS: 10" Newtonian f/5.2
MOUNT:Losmandy G11 equatorial
CAMERA: Philips ToUCam Pro SC1 webcam
FILTERS: None
EXPOSURE: 27/10: 38 x 120s, 22/11: 35 x 180s
DATE/TIME: 27/10/2005 12:53 UTC, 22/11/2005 10:17 UTC
LOCATION: My backyard observatory in west Auckland, New Zealand