An Anti-Balaka fighter, member of a militia opposed to the Seleka rebel group, puts a knife to his throat showing what he would do to any Seleka, on the outskirts of the Boy-Rabe neighborhood in Bangui on December 14, 2013. France raised alarm on December 13 over worsening violence in the Central African Republic, as UN chief Ban Ki-moon urged warring Christians and Muslims to stop the bloodshed that has left more than 600 dead in the past week. (Photo by Ivan Lieman/AFP Photo)

This undated photo provided by NOAA in May 2018 shows aurora australis near the South Pole Atmospheric Research Observatory in Antarctica. When a hole in the ozone formed over Antarctica, countries around the world in 1987 agreed to phase out several types of ozone-depleting chemicals called chlorofluorocarbons (CFCs). Production was banned, emissions fell and the hole shriveled. But according to a study released on Wednesday, May 16, 2018, scientists say since 2013, there’s more of a banned CFC going into the atmosphere. (Photo by Patrick Cullis/NOAA via AP Photo)

The images were taken off the coast of Tonga in the South Pacific. Photographer Grant Thomas said: “Through my images I aim to show off the amazing life we have on our planet in hope of inspiring more people to experience it for themselves and, most importantly, care for it”. (Photo by Grant Thomas/Caters News Agency)

A combination photo shows the faces of various attendees of New York Comic Con in Manhattan, New York, October 8, 2015. The event draws thousands of costumed fans, panels of pop culture luminaries and features a sprawling floor of vendors in a space equivalent to more than three football fields at the Jacob Javits Convention Center on Manhattan's West side. (Photo by Andrew Kelly/Reuters)

This July 2014 image provided by the Bureau of Land Management shows the interior of the Natural Trap Cave in north-central Wyoming. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Scientists have resumed digging for the first time in more than 30 years. (Photo by AP Photo/Bureau of Land Management)

These romantic sepia shots show lovers enjoying quiet, unguarded moments together – but the subjects are not besotted couples; they are fearsome big cats. Freelance snapper Goran Anastasovski has devoted more than 10 years of his life to photographing big cats and other animals. The 46-year-old from Macedonia aims to emphasize their human qualities in his photographs. (Photo by Goran Anastasovski/Caters News)

These beautiful images aim to show the more artistic side of Hawaii’s recent volcano eruption, highlighting the sheer power of Mother Nature and the act of creating new land. Photographer CJ Kale’s breathtaking works show the molten lava in its incredible vibrancy, whether it’s bursting from the ground in fireworks fashion or pouring into surrounding waters, causing steam to rise. (Photo by CJ Kale/Caters News Agency)

A belly dancer performs in a talent show in early morning ceremonies for Groundhog Day on February 2, 2018 in Punxsutawney, Pennsylvania. Punxsutawney Phil, the weather-forecasting groundhog, emerged from his burrow in Pennsylvania on Friday, saw his shadow and predicted six more weeks of winter, despite his rival Staten Island Chuck in New York predicting an early spring. (Photo by Brett Carlsen/Getty Images)