North Korean leader Kim Jong Un, his wife Ri Sol Ju and Song Tao, head of the International Department of Communist Party of China (CPC) Central Committee, applaud with ballet dancers in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang April 17, 2018. (Photo by Reuters/KCNA)

Hwang Bo-young (L), a North Korean defector who was a member of the North Korean National female ice hockey team, prepares for practice with South Korean teammates on March 13, 2006 in Seoul, South Korea. Young, 27-years-old, became a captain of the South Korean National Female Ice Hockey Team. (Photo by Chung Sung-Jun/Getty Images)

A tourist takes photos of an Aurora Borealis display (Northern Lights) over the Bals-Fiord north of the Arctic Circle, near the village of Mestervik late September 30, 2014. (Photo by Yannis Behrakis/Reuters)

The sun rises over the north sea as The Couple by artist Sean Henery sits just of the coast at Newbiggin-by-the-Sea, England, Wednesday October 8, 2014. (Photo by Owen Humphreys/AP Photo/PA Wire)

Northern lights (Aurora borealis) glow brightly over an Inupiaq fish camp along the arctic coast in North Slope, Alaska. (Photo by Steven Kazlowski/Barcroft Media)

Glamorous strongwoman Joan Rhodes exercises her strength whilst tackling housework in her flat in Hampstead, north London, March 1958. (Photo by Ken Harding/BIPs). P.S. All pictures are presented in high resolution.

Dilwyn Green, from North Wales, holds his 7 month old Gold Silkie Bantam which won a 1st prize in its breed at the Poultry Club's 2011 National Show on November 19, 2011 in Stoneleigh, England. (Photo by Oli Scarff/Getty Images)

A South Korean military vehicle drives past barricades at the military check point, near the Demilitarized zone (DMZ) separating South and North Korea on December 20, 2011 in Paju, South Korea. (Photo by Chung Sung-Jun/Getty Images)