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)

A man carrying butchered dogs drives past a pet dog at a dog meat market in Yulin, Guangxi Autonomous Region, June 21, 2015. (Photo by Kim Kyung-Hoon/Reuters)

They say a picture is worth a thousand words, and these striking images of 2017 are no exception. The photo highlights include incredible snapshots of the natural world as well as some awesome animal and human encounters. The vibrant gallery also shows thrill-seekers pushing themselves to the limit with breathtaking stunts captured in perfect clarity. The pictures have been taken by a host of photographers from around the world. Here: The two lion cubs singing their hearts out at Antelope park in Zimbabwe. (Photo by David Jenkins/Caters News Agency)

The tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away from Earth in the southern constellation Carina. (Photo by Reuters/NASA)

A Puffing Billy steam train hauled by locomotive 14A crosses the Monbulk Creek trestle after leaving Belgrave station near Melbourne, October 20, 2014. While the discovery of steam power 200 years ago powered the Industrial Revolution, the world long ago shunted most steam trains onto the sidings of history. (Photo by Jason Reed/Reuters)

A man sits on the window of a burning building before falling from it, in central Lahore May 9, 2013. Fire erupted on the seventh floor of the LDA plaza in Lahore and quickly spread to higher floors leaving many people trapped inside the building. At least three people fell from the high floors trying to avoid fire that engulfed the building, local media reports. (Photo by Damir Sagolj/Reuters)

An undated archive picture shows a dog pulling a Belgian machine gun at an unknown location in northern France. A Viscount in the Armoured Cavalry Branch of the French Army left behind a collection of hundreds of glass plates taken during World War One (WWI) that have never before been published. The images, by an unknown photographer, show the daily life of soldiers in the trenches, destruction of towns and military leaders. The year 2014 marks the 100th anniversary of the start of WWI. (Photo by Collection Odette Carrez/Reuters)