Merit Prize Winner: “A Well Earned Rest in the Sahara”. This photo of Moussa Macher, our Tuareg guide, was taken at the summit of Tin-Merzouga, the largest dune (or erg) in the Tadrat region of the Sahara desert in southern Algeria. Moussa rested while waiting for us to finish our 45-minute struggle to the top. It only took ten minutes of rolling, running, and jumping to get back down. The Tadrat is part of the Tassili N'Ajjer National Park World Heritage area, famous for its red sand and engravings and rock paintings of cattle, elephants, giraffes, and rhinos that lived there when the climate was milder. Photo location: Summit of Tin-Merzouga, Tadrat, Tassili N'Ajjer National Park, Algeria. (Photo and caption by Evan Cole/National Geographic Photo Contest)

Internationally acclaimed German three-dimensional artist Manfred Stader adds finishing touches to his artwork in Cape Town, South Africa on 21 November 2010. Stader created this masterpiece to celebrate the opening of Speedo's first dedicated concept store in Africa. (Photo by Foto24/Gallo Images/Getty Images)

Photographer Vincent Jansen travels throughout Europe, visiting beautiful abandoned places. He explores churches, factories, sanatoriums, mortuaries, villas and theaters, all quietly waiting for renovation or demolition. His photos show a unique perspective on what is happening behind the “no trespassing” signs: where nature is slowly gaining ground and the desolation, loneliness and decay leave their stunning traces. Photo: This piano was located in one of many rooms of a huge chateau in Poland. (Photo by Vincent Jansen)

Taking it all in at Trolltunga, a piece of rock which juts horizontally out of a mountain, 700 metres above lake Ringedalsvatnet in Norway. (Photo by Sam Rogers/GuardianWitness)

“Winter shapes, Moscow river”. Moscow river at this part is never covered by ice. When the temperature is very low it's possible to see a strong fog. Morning light and pipes of the oli factory creates a fantastic landscape. Photo location: Moscow, Russia. (Photo and caption by Sergey Rumyantsev/National Geographic Photo Contest)

“Catch of the Decade”. Can you guess what happened next? Photo location: Katmai National Park, Alaska, USA. (Photo and caption by Aaron Baggenstos/National Geographic Photo Contest)

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.

“Leopard Hunting a Stork”. “One-shot capture. I watched the leopard stalking the stork, I only had time to focus at 400mm, no time to change to high speed, I watched the stork, and as soon as it flapped its wings, I shot one shot”. (Photo by Paul Rifkin/National Geographic Travel Photographer of the Year Contest)