Some of this years best images of the heavens include colliding galaxies, open star clusters, and frozen waterfalls beneath a twinkling night sky. All these photos are winners in the Royal Observatory Greenwichs annual Astronomy Photographer of the Year competition.

The competition is in its fourth year and growing, with a record 800 entrants submitting their cosmic photography. Winners were announced on Sept. 19 in four main categories Deep Space, Our Solar System, Earth and Space, and Young Astronomy Photographer of the Year and three special awards were also handed out.

The overall number one prize and top spot for the Deep Space category went to Martin Pugh for his amazing shot (above) of the Whirlpool Galaxy, which shows two galaxies colliding. Pugh also won in 2009 for his picture of the Horsehead nebula.

Other incredible images showed auroras, the Milky Way, and, particularly popular this year, the Transit of Venus. Being the last transit for 105 years, the event was highly photographed and the subject for two winners: Chris Warren, who won the Our Solar System category, and Paul Haese, who was ranked "highly commended" in the same group.

Here we take a look at all the winners, runners up, and highly commended images. If youd like to see the photos in person, they will be exhibited for free from now until Feb. 2013 at the Royal Observatory.

The following captions are courtesy of the Royal Observatory Greenwich.

Above:

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. A closer look shows even more distant galaxies visible in the background.

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

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Royal Observatory Picks Best Astronomy Photos of the Year