A six-year-old acrobat performs on the opening of a tourist festival in Bozhou, Anhui province, China May 3, 2015. (Photo by Reuters/China Daily)

A Thai policeman patrols around a bar area in central Bangkok, Thailand, August 19, 2015. Thai police on Wednesday issued an arrest warrant for an individual they described as a “foreign man”, in connection with a bomb blast in Bangkok that killed 20 people, including many foreigners. (Photo by Kerek Wongsa/Reuters)

A man from Dinka tribe holds his AK-47 rifle in front of cows in a Dinka cattle herders camp near Rumbek, capital of the Lakes State in central South Sudan December 14, 2013. (Photo by Goran Tomasevic/Reuters)

Nuns react at the arrival of Pope Francis at the St. Mary's school to attend a meeting of clergy and religious in Nairobi, Kenya, 26 November 2015. Pope Francis is on a six days visit that will take him to Kenya, Uganda and the Repulic of Central Africa from 25 to 30 November. (Photo by Daniel Dal Zennaro/EPA)

The ruins of a castle stand above the town of Rocca Calascio, close to Santo Stefano di Sessanio in the province of L'Aquila in Abruzzo, inside the national park of the Gran Sasso e Monti della Laga, Italy, September 7, 2016. (Photo by Siegfried Modola/Reuters)

“El rio mas bonito del Mundo”, the most beautiful river of the world, the “River of five colors”, the “Rainbow River”, or even the “Escaped from Paradise”, are the shimmering appellations that Colombians give to Cano Cristales, a small stream located in the heart of the Macarena National Park, 150 km (93 miles) south of Bogota. Photo: A waterfall is seen at the end of the rainy season, in August, when the water level finally decreases, in the Cano Cristales RIver in the Sierra de la Macarena in Colombia. It has become covered with a bright pink endemic aquatic plant, Macarenia Clavigera. (Photo by Olivier Grunewald)

Protesters shield themselves as police beat them with sticks during a violent demonstration near the India Gate against a gang rape and brutal beating of a 23-year-old student on a bus last week, in New Delhi, India, December 23, 2012. The attack last Sunday has sparked days of protests across the country. (Photo by Kevin Frayer/Associated Press)

“Just hanging out”. As full autumn hits the valley of Hallingdal in Norway, this bear chills out in a tree which seems to barely cover its weight. Photo location: Flå, Hallingdal, Norway. (Photo and caption by Jorgen Tharaldsen/National Geographic Photo Contest)