Pedestrians and traffic cross Tower Bridge as viewed through a glass viewing platform on the high-level Walkways during a preview to launch the new viewing experience at the Tower Bridge Exhibition centre in London on November 10, 2014. The new glass flooring at the Tower Bridge Exhibition 42 metres above the river Thames will allow visitors to gaze down on the bridge and river and allow them to experience the bridge opening from above. (Photo by Andrew Cowie/AFP Photo)

Yalena Leuliette, 7, of Greenbelt, Md., throws seeds from a cattail plant up in the air as she plays while visiting the Kenilworth Aquatic Gardens in northeast Washington, on Sunday, August 9, 2015. Leuliette visits the public garden with her parents a few times a year. (Photo by Jacquelyn Martin/AP Photo)

This picture taken on December 31, 2017 shows an Indian sadhu preparing food at a camp at Sangam, ahead of the Magh Mela festival, in Allahabad. The Magh Mela, which is known as a mini-Kumbh Mela, is scheduled to start January 2 and continue until February 13 with auspicious bathing dates throughout the 45 day period. (Photo by Sanjay Kanojia/AFP Photo)

Inspired by traditional Indian travelling photography studios, Arthur Crestani photographed the inhabitants of Gurgaon, a city built almost entirely by private companies. Arthur Crestani’s “Bad City Dreams” contrasts the glossy ideal sold by developers with urban reality. Here: Luxury Living Bhiwadi: “Sky Club on 18th Floor”. (Photo by Arthur Crestani/The Guardian)

A fledgling solar system containing deep within it enough water vapor to fill all the oceans on Earth five times, located in our Milky Way galaxy about 1,000 light years from Earth in the constellation Perseus. (Photo by Reuters/NASA/JPL-Caltech)

A baby Black-crowned Night Heron squawks in its incubator while being cared for at City Wildlife rescue and rehabilitation center in Washington, DC on May 31, 2017. The heron is one of several that have been brought to CW by the staff at The National Zoo over the past few years. (Photo Linda Davidson/The Washington Post)

Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

In this third of seven sequential photos, Elian Gonzalez is held in a closet by Donato Dalrymple, one of the two men who rescued the boy from the ocean, right, as government officials search the home of Lazaro Gonzalez for the young boy, early morning, April 22, 2000, in Miami, Florida. Armed federal agents seized Elian Gonzalez from the home of his Miami relatives before dawn, firing tear gas into an angry crowd as they left the scene with the weeping 6-year-old boy. This photo won the Prize in 2001. (Photo by Alan Diaz/AP Photo)