Mil Mi-8 combat helicopter flies over Moscow, Russia on May 7, 2019 during the dress rehearsal of a Victory Day air show marking the 74th anniversary of the victory over Nazi Germany in the 1941-1945 Great Patriotic War, the Eastern Front of World War II. (Photo by Sergei Savostyanov/TASS)

In this photo taken on Sunday, March 10, 2019, a little girl laughs during a ritual marking the upcoming Clean Monday, the beginning of the Great Lent, 40 days ahead of Orthodox Easter, on the hills surrounding the village of Poplaca, in central Romania's Transylvania region. Romanian villagers burn piles of used tires then spin them in the Transylvanian hills in a ritual they believe will ward off evil spirits as they begin a period of 40 days of abstention, when Orthodox Christians cut out meat, fish, eggs, and dairy. (Photo by Vadim Ghirda/AP Photo)

The Aurora Borealis (Northern Lights) is seen in the sky in Ivalo of Lapland, Finland on September 27, 2019. (Photo by Alexander Kuznetsov/Reuters)

Wellcome trust employee Zoe Middleton poses behind an artwork entitled “My Soul” by Katharine Dowson, which consists of a laser etched lead chrystal glass formation in the shape of a brain, and was created using the artists own MRI Scan, at Wellcome Collection on March 27, 2012 in London, England. (Photo by Dan Kitwood/Getty Images)

These Arab recruits line up in a barracks square in the British Mandate of Palestine, on December 28, 1940, for their first drill under a British solider. Some 6,000 Palestinian Arabs signed up with the British Army during the course of World War II. (AP Photo)

An employee in a bookshop adjusts packaged cigarettes which have to be sold in identical olive-brown packets bearing the same typeface and largely covered with graphic health warnings, with the same style of writing so the only identifier of a brand will be the name on the packet, in Sydney on December 1, 2012. A new world-first law forcing tobacco companies to sell cigarettes in identical packets came into effect Saturday in Australia in an effort to strip any glamour from smoking and prevent young people from taking up the habit. (Photo by William West/AFP Photo)

Lady Gaga performs at Staples Center on August 11, 2010 in Los Angeles, California. (Photo by Jason Merritt/Getty Images)

Castro's soldiers at Playa de Giron, Cuba, after thwarting the ill-fated US backed 'Bay of Pigs' invasion. (Photo by Graf/Getty Images). April, 1961