A three-month-old Sumatran tiger cub named “Bandar” shows his displeasure after being dunked in the tiger exhibit moat for a swim reliability test at the National Zoo in Washington, on November 6, 2013. All cubs born at the zoo must take a swim test before being allowed to roam in the exhibit. Bandar passed his test. (Photo by Manuel Balce Ceneta/Associated Press)

An Indian girl dressed in traditional attire reacts to camera as she watches a cultural performance during Lohri festival in Jammu, India, Monday, January 13, 2014. Lohri is a celebration of the winter solstice observed by Hindus and Sikhs in northern India. (Photo by Channi Anand/AP Photo)

Britain's skip Eve Muirhead, right, embraces Anna Sloan after defeating Switzerland to win the women's curling bronze medal at the 2014 Winter Olympics, Thursday, February 20, 2014, in Sochi, Russia. (Photo by Robert F. Bukaty/AP Photo)

Kevin and Merith Starren have their picture taken by Merith's brother Mark Ernst (R) and nephew Logan Ernst (L) in front of a 50-foot snowman named “Granddaddy” in Gilman, Minnesota, March 6, 2014. (Photo by Eric Miller/Reuters)

North Korean leader Kim Jong Un (3rd R) and wife Ri Sol Ju (4th L) enjoy an art performance given by the Chongbong Band to mark the 70th anniversary of the founding of the Workers' Party of Korea (WPK) in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on October 19, 2015. (Photo by Reuters/KCNA)

Women dressed in traditional Chinese costumes wait perform in celebration of the Chinese New Year at the Nankinmachi square, China Town on February 8, 2016 in Kobe, Japan. In Nankinmachi, the district known as Kobe Chinatown, tourists enjoyed Chinese food, lion dance and the parade organized to celebrate the Lunar New Year. (Photo by Buddhika Weerasinghe/Getty Images)

The Solar Impulse 2 airplane, flown by test pilot Markus Scherdel, flies off the coast of Oahu during a test flight from Kalaealoa Airfield in Kapolei, Hawaii, March 3, 2016. The solar-powered plane is ready to continue its revolutionary voyage around the world. After the craft was grounded in Hawaii last July due to overheated batteries, it was repaired and upgraded, and a recent initial test flight proved successful. (Photo by Eugene Tanner/Reuters)

Musher Justin Savidis' dogs wait in the truck before the restart of the Iditarod Trail Sled Dog Race in Willow, Alaska March 6, 2016. Mushers and dog sled teams from around the world embark on the first leg of Alaska's grueling Iditarod Trail Sled Dog Race, starting a nearly 1,000-mile (1,609 km) journey through the state's unforgiving wilderness. (Photo by Nathaniel Wilder/Reuters)