A weeping South Vietnamese mother and her three children are shown on the deck of this amphibious command ship being plucked out of Saigon by U.S. Marine helicopters in Vietnam, April 29, 1975. (Photo by AP Photo)

Singer Taylor Swift poses at the 2016 iHeartRadio Music Awards in Inglewood, California, April 3, 2016. (Photo by Danny Moloshok/Reuters)

Farmer Zhang Xianping rides his pig "Big Precious" during an interview with the media, in Zhangjiakou, Hebei province, China, November 2, 2015. Zhang, a pig breeder, instead of killing it, decided to keep the two-year-old "Big Precious" as pet when its weight reached 600 kg, according to local media. (Photo by Reuters/China Daily)

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)

In this photo made Thursday, April 11, 2013, Soviet Jewish World War Two veteran Boris Ginsburg poses for a portrait at his house in the southern Israeli city of Ashdod. Ginsburg, born in Belorussia, was kept by a German garrison in the Lenin ghetto since 1941 until its destruction by partisan units in September 1942. In 1942 he joined the partisans for two years and in 1944 he joined the Red Army as a combat soldier and fought till the and of the war. Ginsubrg demobilized in 1947 and immigrated to Israel in 2001. About 500,000 Soviet Jews served in the Red Army during World War Two, and the majority of those still alive today live in Israel. (Photo by Oded Balilty/AP Photo)

A man flies a kite on the Bund while buildings of Pudong's Lujiazui financial district stand across the Huangpu River as the sun rises in Shanghai, China, on Friday, October 2, 2015. (Photo by Qilai Shen/Bloomberg)

People walk along Beachy Head, close to Eastbourne on the south coast of England on April 12, 2020, as life in Britain continues over the Easter break, during the nationwide lockdown to combat the novel coronavirus pandemic. Britain's Prime Minister Boris Johnson was making “very good progress” on Saturday in his recovery in hospital from coronavirus, officials said, as the country's deaths toll from the disease approached the grim milestone of 10,000. (Photo by Ben Stansall/AFP Photo)

Medical workers wearing protective gear to protect against coronavirus infection, carry a patient at infectious diseases hospital where patients with coronavirus are treated in St.Petersburg, Russia, Wednesday, June 3, 2020. (Photo by Dmitri Lovetsky/AP Photo)