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)

In this third of seven sequential photos, Elian Gonzalez is held in a closet by Donato Dalrymple, one of the two men who rescued the boy from the ocean, right, as government officials search the home of Lazaro Gonzalez for the young boy, early morning, April 22, 2000, in Miami, Florida. Armed federal agents seized Elian Gonzalez from the home of his Miami relatives before dawn, firing tear gas into an angry crowd as they left the scene with the weeping 6-year-old boy. This photo won the Prize in 2001. (Photo by Alan Diaz/AP Photo)

This picture taken on February 23, 2014 shows participants wearing dresses running half-naked in the annual 3.5 km Undie Run held in the Olympic Forest Park smog-covered Beijing. Some 200 participants took part in this event, many of them with gas masks, as dangerous smog blighted swathes of northern China in recent days. (Photo by AFP Photo/STR)

In this November 27, 2019 photo, Wadlande Pierre, right, talks on her mobile phone as she helps her mother, Vanlancia Julien, center, at their fruit and vegetable stand on a sidewalk in Delmas, a district of in Port-au-Prince, Haiti. Pierre, 23, said she temporarily moved in with her aunt in the southwest town of Les Cayes to escape the violent protests in Port-au-Prince. However, she had to move back to the capital because there was no gas, power or water in Les Cayes, and food was becoming scarce. (Photo by Dieu Nalio Chery/AP Photo)

Unnati, 6 years old, at home with his sister Ishika, 4 years old, in the Mahamai Ka Bagh neighborhood. Unnati was born to parents contaminated by a carcinogenic and mutagenic water supply. This year marks the 31st anniversary of the 1984 Union Carbide gas tragedy that killed thousands of citizens of Bhopal within 72 hours and has gone on to claim thousands more as a result of the polluted environment. (Photo by Giles Clarke/Getty Images)

Palestinian protesters take cover amid clashes with Israeli security forces during a raid in the old city of Nablus, in the occupied West Bank, on May 9, 2023. The Israeli army said its troops had entered Nablus in the northern West Bank, with residents telling AFP they heard explosions during the raid. The Palestinian Red Crescent Society said its medics treated 145 injuries in Nablus, the majority from tear gas inhalation while a dozen people were shot with live fire. (Photo by Jaafar Ashtiyeh/AFP Photo)

An injured supporter of Kenyan opposition leader Raila Odinga receives assistance in Nairobi, Kenya on November 17, 2017. Kenyan police have used tear gas and water cannons to disperse supporters of opposition leader Raila Odinga who are trying to gather near the country's main airport and Uhuru park to welcome him back from an overseas trip. (Photo by Baz Ratner/Reuters)

Buddy Mae Walker (R), 4, looks at herself in the mirror while trying on a child respirator provided by the non-profit TeamRaccoonPDX on October 6, 2020 in Portland, Oregon. We told them their grandparents sent them space suits to keep them safe, Jessica Walker said of the respirators, which the family sought out after police used tear gas near their residential street. (Photo by Nathan Howard/Getty Images)