The "Whirlpool Galaxy"

This beautifully composed image of the Whirlpool Galaxy combines fine detail in the spiral arms with the faint tails of light that show its small companion galaxy being gradually torn apart by the gravity of its giant neighbour.

This image was the overall winner in the Royal Observatory's contest for best astronomy photos of the year.  Another dozen photos are posted at Wired Science.

Image credit: Martin Pugh, winner for Deep Space and overall winner