Mary McHugh mourns her slain fiance Sgt. James Regan at “Section 60” of the Arlington National Cemetery May 27, 2007. Regan, a US Army Ranger, was killed by an IED explosion in Iraq. (Photo by John Moore/Getty Images)

Police dog handlers wait outside the Loftus Road stadium after FA Cup Fourth Round between Queens Park Rangers and Chelsea on January 28, 2012 in London, England. Security has been stepped up after QPR player Anton Ferdinand recieved a package containing a bullet. (Photo by Dan Kitwood/Getty Images)

Members of the media film as a ranger performs a post mortem on the carcass of a rhino after it was killed for its horn by poachers at the Kruger national park in Mpumalanga province August 27, 2014. Rhino poachers in South Africa now risk giving themselves away when they shoot thanks to a high-tech, gunfire-detection system being piloted in the country's flagship Kruger National Park. The stakes are high, for rhinos are being slain in escalating numbers for their prized horns, alarming both conservationists and the government since wildlife in South Africa is an important tourist draw. (Photo by Siphiwe Sibeko/Reuters)

Kenya Wildlife Service (KWS) rangers load a tranquilized elephant onto a truck during a translocation exercise to Ithumba Camp in Tsavo East National Park, in Solio Ranch in Nyeri County, Kenya, February 21, 2018. Wildlife officials in Kenya kicked off a relocation operation for 30 elephants, fitting monitoring collars on the tranquilized animals before using cranes to swing them, inverted with bound feet and scything tusks, onto flatbed trucks. (Photo by Thomas Mukoya/Reuters)

Orphaned baby rhinos seen on August 28, 2014 in Lewa Wildlife Conservancy, Ngare Ndare Forest, Kenya. Lewa Wildlife Conservancy in Kenya is hand-raising three orphaned baby rhinos; Nicky, Hope and Kilifi. Baby rhino Hope was rescued by rangers when the poachers killed his mother – now he is been taken care off 24 hours-a-day at Lewa Wildlife Conservancy. The wildlife reserve hit the headlines when Prince William proposed to Kate Middleton there in 2010. Rhinos around the world are becoming extinct as a result of the brutal poaching fuelled by an illegal international market for their horns. (Photo by Luca Ghidoni/Barcroft Media)

Aurorae category runner-up: Lone Tree under a Scandinavian Aurora by Tom Archer (UK). The photographer decided to explore the area around the hotel on a very crisp -35C evening in Finnish Lapland. When he found this tree, he decided to wait for the misty conditions to change and could not believe his luck when the sky cleared and the aurora came out in the perfect spot. Archer spent about an hour photographing it before his camera started to lock up because of the harsh conditions, but by then he was happy to call it a night. (Photo by Tom Archer/2020 Astronomy Photographer of the Year)

A runner in fancy dress participates in the Virgin London Marathon 2013 on April 21, 2013 in London, England. (Photo by Tom Dulat/Getty Images)

American free climber Dean Potter walks on a 41-meter-long and two-centimeter-wide slackline over Enshi Grand Canyon at an altitude of 1,800m on April 22, 2012 in Enshi, Hubei Province of China. Potter successfully finished the lone slackline walk in about three minutes without taking any protective measures. (Photo by ChinaFotoPress/ChinaFotoPress)