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 September 27, 2017 file photo, girls walk past a wall riddled with bullet holes from shootings between rival drug traffickers, at the Rocinha slum, in Rio de Janeiro, Brazil. Violence is on the rise in Rio's slums after several years of decline, and the killings of kids have shocked even residents long inured to deaths from gangs and police. (Photo by Silvia Izquierdo/AP Photo)

In this September 14, 2017 photo, young women pose for a photo inside their squatter building that used to house the Brazilian Institute of Geography and Statistics (IBGE) in the Mangueira slum of Rio de Janeiro, Brazil. Many lower-middle class Brazilians who gained ground during the boom years have since slid back closer to the poverty line. (Photo by Felipe Dana/AP Photo)

North Korean cheerleaders arrive at a rest stop, or service station, as their bus convoy carrying a 280- member delegation on its way to the 2018 Pyeongchang winter Olympic games, makes its way past Gapyeong on February 7, 2018 More than 200 young North Korean women arrived in South Korea to root for athletes from both sides of the peninsula at the Winter Olympics. (Photo by Ed Jones/AFP Photo)

A young woman flashes the victory sign in front of a bonfire as Turkish Kurds gather during Newroz celebrations for the new year in Diyarbakir, southeastern Turkey, on March 21, 2018. Newroz (also known as Nawroz or Nowruz) is an ancient Persian festival, which is also celebrated by Kurdish people, marking the first day of spring, which falls on March 21. (Photo by Ilyas Akengin/AFP Photo)

A 180 degrees rotated photograph shows the shadows of Polina (L), a six-year-old Belarusian first grade school girl, and her father, cast on the street while on their way to Polina's first day of school, which marks the traditional start of the academic year, in Minsk, Belarus, 02 September 2019. The start of a new academic year in Belarus, officially called Day of Knowledge, is a festive day for all school and university students in the country. (Photo by Tatyana Zenkovich/EPA/EFE)

Two young dancers take pictures while waiting for the start of the Koenji Awa-Odori dance festival, in the Koenji neighborhood of Tokyo. Saturday, August 24, 2019, Started in the 1950s, the Koenji Awa-Odori has grown to be one of Tokyo's largest and most popular summer festivals an estimated 10,000 dancers participating in the dance festival. Hundreds of thousands of spectators gather in the neighborhood to watch the two-day summer spectacle. The event is held on the last weekend of August each year. (Photo by Jae C. Hong/AP Photo)

A young female demonstrator is arrested by police during clashes in the Causeway Bay area of Hong Kong, China on October 6, 2019. Hundreds of thousands of protesters marched through the city's streets in defiance of the new “no-mask” law, which was introduced two days ago as demonstrations roll into a 14th week. (Photo by Rick Findler/EPA/EFE/Rex Features/Shutterstock)