Two young boys kneel on stools on either side of a round table as one uses a match to this the other's cigarette, November 12, 1928. (Photo by FPG/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)

An athlete dressed as a clown jumps into the Mediterranean sea as he takes part in the Copa Nadal in the Spanish port of Barcelona in Barcelona, Spain, Sunday, December 25, 2016. The Copa Nadal (Christmas Cup) is a traditional swimming competition that takes place in Barcelona every December 25th, where participants swim 200 meters in the open sea in the port of Barcelona. (Photo by Manu Fernandez/AP Photo)

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)

An Indian girl smiles under a water splash at a water park as the temperatures reached 38 degree Celsius in Calcutta, eastern India, 12 June 2016. The summer or pre-monsoon season lasts from March to July in eastern India with the highest day temperatures ranging from 38 to 45 degrees Celsius. (Photo by Piyal Adhikary/EPA)

Hundreds of people pack the Canaveral national seashore's Playalinda Beach as a United Launch Alliance Atlas V rocket, carrying a U.S. Navy communications satellite, lifts off from Complex 41 at the Cape Canaveral Air Force Station, Friday, June 24, 2016, in Cape Canaveral, Fla. The satellite is designed to significantly improve ground communications for U.S. forces on the move. (Photo by Craig Rubadoux/Florida Today via AP Photo)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

A love story with two log choppers. “In 1993, I was working on a project about life in the Olomouc region of Czechoslovakia. One day, I came to the village of Dlouhá Loučka-Křivá and went into a courtyard where I saw two old people, a husband and wife, sawing firewood for winter. They were working quietly, concentrating. I watched them fetch a beam from a wrecked barn, but they didn’t discuss how they planned to carry it to the saw. The woman faced one way, the man the other. When they realised, the woman eventually turned and followed her husband. The picture I took is the picture of many relationships – when each partner wants something different, but they have to come to an agreement, pull together eventually”. (Photo by Jindrich Streit)