A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

A citizen rides in smog on December 20, 2016 in Jinan, Shandong Province of China. Air quality index (AQI) readings exceeded 400 and some schools have suspended classes in Jinan. (Photo by VCG/VCG via Getty Images)

A labourer pulls a cart loaded with sacks of spices at a wholesale spice and chemical market in the old quarters of Delhi, India, December 19, 2016. Picture taken December 19, 2016. (Photo by Adnan Abidi/Reuters)

ESA astronaut Tim Peake posted this stunning image on his social media channels, commenting: “Station passed through magnificent aurora Australis last night”. Tim is set to return to Earth on 18 June 2016, bringing his six-month Principia mission to the ISS to an end. During his stay he performed more than 30 scientific experiments for ESA and taking part in numerous others from ESA's international partners. ESA and the UK Space Agency have partnered to develop many exciting educational activities around the Principia mission, aimed at sparking the interest of young children in science and space. (Photo by Tim Peake/ESA/NASA)

Guillermo Rodriguez and Sports Illustrated Swimsuit Issue cover model Kate Upton arrive at Club SI Swimsuit hosted by the Pure Nightclub at Caesars Palace at the Pure Nightclub at Caesars Palace on February 16, 2012 in Las Vegas, Nevada. (Photo by Michael Loccisano/Getty Images for Sports Illustrated)

Joaldunaks return in a trailer to their town at the end of Carnival between of the Pyrenees villages of Ituren and Zubieta, northern Spain, Monday, February 1, 2016. In one of the most ancient carnivals in Europe, dating from before the Roman empire, companies of Joaldunak (cowbells) made up of residents of two towns, Ituren and Zubieta, parade the streets costumed in sandals, lace petticoats, sheepskins around the waist and shoulders, coloured neckerchiefs, conical caps with ribbons and a hyssop of horsehair in their right hands and cowbells hung across their lower back. (Photo by Alvaro Barrientos/AP Photo)

An Israeli soldier prays in front of a tank at a military staging area near the border with the Gaza Strip, in this July 24, 2014 file photo. Israel's long-running struggle to balance modern standards with Jewish tradition has come to a head in the military, where new orders curtailing beards among soldiers have met protests from some rabbis. (Photo by Nir Elias/Reuters)

People cross the street in central Pyongyang, North Korea May 4, 2016. (Photo by Damir Sagolj/Reuters)