History enthusiasts dressed as soldiers fight during the re-enactment of Napoleon's famous battle of Austerlitz near the southern Moravian town of Slavkov u Brna November 29, 2014. Hundreds of history enthusiasts took part in the re-enactment of the battle to mark its 209th anniversary. (Photo by David W. Cerny/Reuters)

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)

Buildings in Nogales, Mexico (R) are separated by a border fence from Nogales, Arizona, United Sates, October 9, 2016. Building a wall along the U.S.- Mexico border has been a contentious subject in this year's U.S. presidential election. In parts of California and Arizona, a wall already exists. It runs across rocky deserts, flowing sand dunes and miles of agricultural land. (Photo by Mike Blake/Reuters)

Football Soccer, Russia vs Wales, EURO 2016, Group B, Stadium de Toulouse, Toulouse, France on June 20, 2016. A Russian fan cheers before the match. (Photo by Sergio Perez/Reuters)

A supporter of the team of Ukraine cheers prior to the Euro 2016 Group C soccer match between Ukraine and Poland at the Velodrome stadium in Marseille, France, Tuesday, June 21, 2016. (Photo by Thanassis Stavrakis/AP Photo)

Skiers and snowboarders in swimwear during the Grelka Fest-2019 Festival at the Sheregesh ski resort, Kemerovo Region, Russia on April 13, 2019. (Photo by Kirill Kukhmar/TASS)