Galaxies with Rings

Galaxies with Rings
(a) A composite image of the Cartwheel Galaxy. This ring-shaped assemblage 500 million ly from Earth is likely the result of one galaxy,
probably the blue-white one below it at the eight o’clock position, having passed through the middle of the larger one.
Astronomers suspect that the passage created a circular density wave in the Cartwheel that stimulated a burst of star formation,
creating many bright blue and white stars. Ultraviolet is in blue, visible light in green, infrared in red, and X ray in violet