This is the amazing moment a heroic hippo saved a gnu from certain death. After being bitten by a crocodile, the large antelope is seen being dragged slowly under the water. But in a miraculous turn of events, a nearby hippo is seen making its way across the water to help the animal in its hour of need. Photo: One of the biggest hippos protects the gnu as it makes its way back to the shoreline, guarding it from any further attacks. (Photo by Vadim Onishchenko/Caters News)

These Northern Lights “rainbows” have turned the sky greener than the Earth below. Vitaly Istomin, 26, spent several nights in freezing conditions under the stars in northern Russia’s Khibiny Mountains to capture the aurora’s “rainbows”. (Photo by Vitaly Istomin/Caters News Agency)

Samburu women of the Lorubai traditional dance group are seen wearing traditional beaded necklaces during a Peace Marathon for pastoralist communities at the Archers post in Isiolo, Kenya on April 26, 2018. The aim of the event is to bring the warring pastoralist communities of Samburu, Turkana, Borana and others together, and end the rivalry due to scarcity of pasture and water in the region. The peace marathon is organized by Kenya's Northern Rangeland Trust. (Photo by Simon Maina/AFP Photo)

The sun rises between Sgurr nan Gillean and Knight’s Peak, Black Cuillin, Isle of Skye. (Photo by Adrian Trendall/Mountain Photo of the Year)

Christ the Redeemer is seen from the Vista Chinesa (Chinese View) during sunrise in Rio de Janeiro, Brazil, May 4, 2016. Rio de Janeiro is a marvel and a mess all at once. When it hosts the first ever Olympics in South America, starting Aug. 5, visitors will see a city whose stunning topography – stark, verdant mountains loom over packed and playful beaches – competes only with the drama of daily life here. (Photo by Ricardo Moraes/Reuters)

Chinese artist Kong Ning poses in a costume symbolizing a butterfly, which is decorated with 365 masks on its wings to represent the number of days in a year, during her performance art at the Badaling section of the Great Wall on the outskirts of Beijing January 1, 2015. Kong, whose works include themes related to China's air pollution problem, named her new performance art “Hua Die” (transforming into a butterfly) and performed it on the first day of the new year as she hopes that China has clean air for this year. (Photo by Kim Kyung-Hoon/Reuters)

A christmas teddy bear is wheeled along on a trolley at the Steiff stuffed toy factory on November 23, 2012 in Giengen an der Brenz, Germany. Founded by seamstress Margarethe Steiff in 1880, Steiff has been making stuffed teddy bears since the early 20th century ever since her nephew Richard Steiff exhibited the first commercially produced teddy bear in Europe in 1903. Teddy bears are among the most popular children's toys and the company is hoping for a strong Christmas season. (Photo by Thomas Niedermueller)

An anti-government protester shouts at a police officer in downtown Caracas, Venezuela, Wednesday, May 10, 2017. Opponents of President Nicolas Maduro will attempt to march to the Supreme Court to protest its decision to gut the opposition-controlled congress of its powers, a ruling that was quickly rescinded under a barrage of international criticism but that set off weeks of political unrest that have left some three dozens killed. (Photo by Fernando Llano/AP Photo)