Huge pack of starlings in the sky of the Negev, Israel, on January 21, 2013. Birds are turned in evening twilight before settling to sleep. (Photo by Eliyahu Hershkovitz)

A lighting bolt flashes in the sky as U.S. Army M1A1 Abram tanks roll through the desert December 9, 2002 near the Iraqi border in Kuwait. (Photo by Joe Raedle/Getty Images)

The rising sun illuminates the sky above the spires of a church in Vienna, Austria, November 17, 2015. (Photo by Heinz-Peter Bader/Reuters)

A Virgin Atlantic passenger plane flies in the sky with the moon seen in the background, in London, Britain January 19, 2016. (Photo by Toby Melville/Reuters)

A girl jumps to touch cherry blossoms in full bloom in Fussa, outskirts Tokyo, Japan, 05 April 2014. Temperatures being very constant made blossoms to keep full bloom for holiday makers. (Photo by Kimimasa Mayama/EPA)

Members of a Star Wars fan club wear costumes of movie characters as they join a midnight premiere of the new Star Wars movie “Star Wars: The Force Awakens” at a cinema in Stuttgart, Germany, late 16 December 2015 night. Numerous fans of the science fiction movie series were gathering to attend one of the midnight premiere screenings all over Germany of the latest movie of the epic series – “Star Wars: The Force Awakens”. (Photo by Nikolai Huland/EPA)

Six month- old baby elephant “Clear Sky” is kept afloat with the help of a harness during a hydrotherapy session at a local veterinary clinic in Chonburi Province on January 5, 2017. After losing part of her left foot in a snare in Thailand, baby elephant 'Clear Sky' is now learning to walk again – in water. (Photo by Roberto Schmidt/AFP Photo)

Shooting star by Tony Wu, US/Japan. Winner, underwater. The electrifying reproductive dance of a giant sea star. As the surrounding water filled with sperm and eggs from spawning sea stars, Wu faced several challenges. Stuck in a small, enclosed bay with only a macro lens for photographing small subjects, he backed up to squeeze the undulating sea star into his field of view. The dancing posture of spawning sea stars rising and swaying may help release eggs and sperm, or may help sweep the eggs and sperm into the currents where they fertilise together in the water. Kinko Bay, Japan. (Photo by Tony Wu/Wildlife Photographer of the Year)