A pilot looks up from a U.S. F-22 Raptor fighter as it prepares to refuel in mid-air with a KC-135 refuelling plane over European airspace during a flight to Britain from Mihail Kogalniceanu air base in Romania April 25, 2016. (Photo by Toby Melville/Reuters)

Jolon Clinton, 15, (L), and her sister, Halcy, 17, take photos of a fissure near their home on the outskirts of Pahoa during ongoing eruptions of the Kilauea Volcano in Hawaii, U.S., May 14, 2018. (Photo by Terray Sylvester/Reuters)

A novice monk holds a book during an inauguration ceremony at Jogye temple in Seoul, May 11, 2015. Ten children on Monday were given the opportunity to experience life as Buddhist monks by staying at the temple until Buddha's birthday in two weeks. The writing on the book reads, “Novice Monk Prayer”. (Photo by Thomas Peter/Reuters)

A woman looks at head of bluefin tuna on display in front of a store at Tsukiji fish market in Tokyo, Monday, February 19, 2018. The large bluefin are particularly valuable in Japan, where they are considered a premium sushi and sashimi fish. A single fish sold for more than $1.75 million at an auction in Japan in 2013. (Photo by Koji Sasahara/AP Photo)

This picture taken on January 3, 2019 shows a Vietnamese woman collecting incense sticks in a courtyard in the village of Quang Phu Cau on the outskirts of Hanoi. In Vietnam's “incense village”, hundreds of workers are hard at work dying, drying and whittling down bamboo bark to make the fragrant sticks ahead of the busy lunar new year holiday. (Photo by Manan Vatsyayana/AFP Photo)

Servicewomen march during a rehearsal for the Independence Day military parade in central Kiev, Ukraine on August 20, 2018. (Photo by Gleb Garanich/Reuters)

A South China Tiger cub meets public at Guangzhou Zoo on June 22, 2017 in Guangzhou, Guangdong Province of China. Guangzhou Zoo boasts of the successful breeding of South China Tiger cub after 15 years. (Photo by VCG/VCG via Getty Images)

Star Wars fan Mike Deguzman practices with a toy lightsaber after purchasing some new toys that went on sale at midnight in advance of the film “Star Wars: The Force Awakens” in Times Square in the Manhattan borough of New York, September 4, 2015. (Photo by Carlo Allegri/Reuters)