Team Strong Silvers member Ngai Hin Kwok, 66, works out as teammate Ng Siu Chi, 57, watches at a stadium in Singapore March 15, 2015. Team Strong Silvers, is a group of senior citizens who train in calisthenics. The trio trains individually at least three times a week, and meets up for joint calisthenics at least twice a month. (Photo by Edgar Su/Reuters)

A Nepalese vetinary and technical team release a rhino after it is relocated in Chitwan National Park some of 250 Kilometer South of Kathmandu on April 4, 2017. Conservationists on April 3 captured a rare one-horned rhinoceros in Nepal as part of an attempt to increase the number of the vulnerable animals, which are prized by wildlife poachers. Five rhinos – one male and four female – will be released into a national park in Nepal's far west over the coming week in the hope of establishing a new breeding group. (Photo by Prakash Mathema/AFP Photo)

South Korean rescue members wearing chemical protective suits walk past a monster character (R) during an anti-terror drill as part of a disaster management exercise at the COEX shopping and exhibition center in Seoul on May 20, 2016. South Korea is holding its 2016 Safe Korea anti-disaster exercise this week against terrorist threats and natural disasters. (Photo by Jung Yeon-Je/AFP Photo)

Some of the best entries so far in the 2016 Insight Astronomy Photographer of the Year competition. There are two weeks left to enter, and the winners will be announced in September. Here: Aurora over Laksvatn Fjord, Laksvatn, Norway. The aurora borealis dances in the skies over the town of Laksvatn, with the Milky Way to the left. The image is a single shot with no compositing, only post-processing to bring out the aurora, and some colour corrections. The photographer Matt Walford said: “I love the way the northern lights look like they are just wistfully dancing over the fjord, framed by the mountains on either side”. (Photo by Matt Walford/National Maritime Museum)

A Chinese exhibitor checks lighting products at a booth during the China Import and Export Fair, also known as Canton Fair, in the southern Chinese city of Guangzhou October 15, 2015. Around two thirds of exporters at China's largest trade fair expect the slowdown in their markets to persist for at least six months, a Reuters poll has found, with the country expected to announce its slowest economic growth in decades early next week. (Photo by Bobby Yip/Reuters)

A Shiite fighter from the Hashed al-Shaabi (Popular Mobilisation) patrols in the village of Ayn Nasir, south of Mosul, on October 29, 2016, after recapturing it from Islamic State group jihadists in an ongoing operation to retake the city of Mosul. Iraqi paramilitary forces launched an operation to cut the Islamic State group's supply lines between its Mosul bastion and neighbouring Syria, opening a new front in the nearly two-week-old offensive. (Photo by Ahmad Al-Rubaye/AFP Photo)

Competitors perform at the World Irish Dance Championship on April 13, 2014 in London, England. The 44th World Irish Dance Championship is currently running at London's Hilton London Metropole hotel, and will host approximately 5,000 dancers competing in solo, Ceili, modern figure choreography and dance drama categories during the week long event. (Photo by Dan Kitwood/Getty Images)

Cassandra Cantu shields her 7-week-old puppy Kamala from the snow as she walks with friends in the Bear Creek Dog Park in Colorado Springs, Colo., Sunday, May 11, 2014. A spring storm that has brought over a foot of snow to parts of Colorado, Wyoming and Nebraska and thunderstorms and tornadoes to the Midwest was slowing down travelers and left some without power Monday morning. (Photo by Mark Reis/AP Photo/The Gazette)