The competition, which is run by the Royal Observatory Greenwich in association with BBC Sky at Night Magazine, is now in its sixth year and has received over 2,500 entries. Photo: Centre of the Heart Nebula by Ivan Eder (Hungary). Situated 7500 light years away in the “W”-shaped constellation of Cassiopeia, the Heart Nebula is a vast region of glowing gas, energized by a cluster of young stars at its centre. The image depicts the central region, where dust clouds are being eroded and moulded into rugged shapes by the searing cosmic radiation. (Photo by Ivan Eder)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

“Body blading (also known as buggy rollin') is an extreme sport that involves descending down a slope while wearing a flexible aerodynamic plastic roller suit that has wheels on the feet, knees, torso, and arms. This suit was created by Jean-Yves Blondeau, and he is one of the premier body bladers. Body blading is similar to roller blading, and in fact a body blader often starts out using the rollers on their feet in the same fashion as roller blades in order to gain initial speed, but then the rider generally assumes a position laying on the stomach facing down the hill. A body blader is capable of reaching very high speeds. Maneuverability is achieved by moving the body into various positions to change direction”. – Wikipedia

Photo: French designer Jean-Yves Blondeau demonstrates his “Buggy Rollin” suit during a performance on August 16, 2007 in Beijing, China. Blondeau is able to roll along in any position and can achieve high speeds wearing the suit. (Photo by China Photos/Getty Images)

It’s a classic tale of dictatorship gone wrong and the fight for freedom. Like in any good battle, there’s fire, albeit from firecrackers, but the ammunition in this one is – flour. It takes place in a Hemingway-esque Spanish village. The battle of “Enfarinats” in celebration of the Els Enfarinats festival, rages on on December 28, 2012 in Ibi, Spain. Citizens of Ibi annually celebrate the festival with a fight using flour, eggs and firecrackers. The battle takes place between two groups, a group of married men called “Els Enfarinats” who take the control of the village for one day pronouncing a number of ridiculous laws and fining the citizens that infringe them and a group called “La Oposicio” who try to restore order. At the end of the day the money collected from the fines is donated to charitable causes in the village. The festival has been celebrated since 1981 after the town of Ibi recovered the tradition but the origins remain unknown.

Photo: A Reveller smokes during the battle of “Enfarinats”, a flour fight in celebration of the Els Enfarinats festival. (Photo by David Ramos)

“A fter the former Soviet Union conducted its first nuclear test in August 1949, the US reevaluated its postwar defense policies. With the US monopoly on atomic weapons broken, military and political leaders chose to diversify the American stockpile by developing thermonuclear and tactical nuclear weapons. One of the more interesting concepts to come out of this period was atomic artillery, which was successfully tested at the Nevada Proving Grounds (now the Nevada Test Site) in May 1953”. – Alan Carr. Photo: Atomic Annie at work during the Upshot-Knothole test series, 1953. (Photo by Los Alamos National Laboratory/US Army)

Astronomer, space scientist and meteorologist Andrea Opitz, senior research associate of the Space Physics and Space Technology Department of Hungarian Academy of Sciences (MTA) Wigner Research Centre for Physics (2R) wears a space suit during a cosmology exhibition in Budapest, Hungary, 03 March 2016. The photo series was created to mark the International Women's Day (IWD), which was marked for the first time in 1911 and is celebrated on 08 March since 1913. (Photo by Bea Kallos/EPA)

An aerial view of a livestock enclosure of the Himba people, in October, 2014, in the Namib Desert, Namibia. A photographer has captured a bird's eye view of the stunning Namib Desert from a paraglider. Theo Allofs travels the world taking stunning pictures of untouched landscapes from a unique perspective. Soaring 300 metres above ground, Theo shot the yellow sand dunes, dry red river beds and remote townships in Namibia. (Photo by Theo Allofs/Barcroft Media)

Mount Sinabung is seen during an eruption from Surbakti village in Karo, North Sumatra, Indonesia, April 20, 2015. The local government is preparing the relocation of residents from three of the villages that were destroyed. (Photo by Tibta Pangin/Getty Images/Anadolu Agency)