Dhruva Aliman does a back somersault as he dismounts from a slackline on the beach at Santa Monica, California on October 19, 2014. Slackline is a balance sport where a line of webbing is adjusted at different levels of tension between two anchor points and participants (called slackers) perform tricks and stunts including somersaults. (Photo by Mark Ralston/AFP Photo)

A zoo performer smiles as he puts his head between the jaws of a crocodile during a performance for tourists at the Sriracha Tiger Zoo, in Chonburi province, east of Bangkok,Thailand, June 7, 2016. (Photo by Chaiwat Subprasom/Reuters)

A Guarani Mbya man smokes a pipe next to a cut tree as he occupies land as a protest against real estate developer Tenda which plans to build apartment buildings here, next to his indigenous community's land in Sao Paulo, Brazil, Thursday, February 6, 2020. In response to an injunction filed by the builder, a judge has authorized the eviction of the indigenous protesters from the builder's property. (Photo by Andre Penner/AP Photo)

A British Army Rolls Royce armoured car outside the Royal Ulster Constabulary police station on York Street in Belfast following riots after an Orange Order parade. (Photo by Fox Photos/Getty Images). 20th June 1935

Breath at sunset, captures a sea turtle at a dive site called Black Rock. Kāʻanapali, Hawaiʻi, August 2013. (Photo by Christopher Doherty/Smithsonian.com)

A girl takes pictures after opening ceremony at Shanghai Disney Resort in Shanghai, China, June 16, 2016. (Photo by Aly Song/Reuters)

2014 Underwater Photography Photo Contest winners, Wide angle marine life category, 3rd place. (Photo by Valda Fraser/UnderwaterPhotography.com)

The Royal Observatory just announced its Astronomy Photographer Of The Year 2013 winners. Australian photographer Mark Gee was chosen among a thousand amateur and professional photographers around the globe to win the top title. His work is part of an exhibition of the winning photographers, which opened on Sept. 19 at the Royal Observatory Greenwich. The Royal Observatory shared with us the winners and notable mentions of the competition. Their descriptions of the prizewinners can be found below the images.