Amundsen-Scott South Pole Station experiences months of darkness. The sun dips below the horizon on March 21, after which follows several weeks of twilight before complete darkness results. Photo taken on June 25, 2009. (National Science Foundation/Jeremy Johnson)

Iraqis who have fled fighting between security forces and al-Qaida inspired militants in their hometown of Tal Afar arrive in a car at Germawa camp for displaced Iraqis, in a hot dusty plain in the largely-autonomous Kurdish area of Dahuk, 260 miles (430 kilometers) northwest of Baghdad Tuesday, June 17, 2014. (Photo by AP Photo)

An Israeli army officer gives explanations to journalists during an army organised tour in a tunnel said to be used by Palestinian militants for cross-border attacks, July 25, 2014. (Photo by Jack Guez/Reuters)

Model Karlie Kloss has her dress adjusted backstage prior to the Off-White ready to wear Fall-Winter 2019-2020 collection, that was presented in Paris, Thursday, February 28, 2019. (Photo by Thibault Camus/AP Photo)

A student from the General Yermolov Cadet School performs with models of swords during celebrations of Maslenitsa, or Pancake Week, a pagan holiday marking the end of winter, in southern city of Stavropol, Russia, March 6, 2019. (Photo by Eduard Korniyenko/Reuters)

Villagers play traditional games as they take part in a Chyrachka rite during the Shrovetide celebration in the village of Tonezh, some 280 km of Minsk, on March 10, 2019. Chyrachka is a kind of birds that live in this area. (Photo by Sergei Gapon/AFP Photo)

In this Saturday, April 13, 2019, file photo, Mariah Bell, center, of the U.S. reacts to her score with her teammates after performing her women's free program routine during the ISU World Team Trophy Figure Skating competition in Fukuoka, southwestern Japan. (Photo by Toru Hanai/AP Photo)

Camel racing made its debut in Paxford, Gloucestershire, England yesterday at a point-to-point event on April 22, 2019. Each of the four camels was sponsored by a local pub. (Photo by Paul Nicholls/The Times)