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)

Models promote a condom brand at the first Shenzhen s*x Culture Festival on September 21, 2007 in Shenzhen of Guangdong Province, China. The festival aims to increase awareness about reproductive health and popularise s*x education. (Photo by China Photos/Getty Images)

A young woman looks at her smartphone sitting in front of a mannequin use to keep social distancing at a Chinese cuisine restaurant in Tokyo, Japan, 27 July 2020. Japan's total number of COVID-19 cases crossed the 30,000 line showing the new coronavirus pandemic is spreading across the country and not only in Tokyo and Osaka megalopolis. (Photo by Franck Robichon/EPA/EFE)

English actress Diana Rigg as “Emma Peel” is tied to a railway track as a miniature train advances on her in a scene from the television series “The Avengers” in 1968. Rigg died at her home in London on 10 September 2020, at the age of 82. (Photo by Popperfoto via Getty Images/Getty Images)

In this April 14, 2014 file photo, Hamamatou Harouna, 10, who lost the use of her legs to polio, crawls to the restroom on the grounds of the Catholic Church where she and hundreds of others found refuge after fleeing violence in her village, in Carnot, Central African Republic. Health authorities on Tuesday, August 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (Photo by Jerome Delay/AP Photo/File)

Rajesh Babu, a police officer, wearing a helmet depicting coronavirus, requests a commuter to stay at home during a 21-day nationwide lockdown to limit the spreading of coronavirus disease (COVID-19), in Chennai, India, March 28, 2020. (Photo by P. Ravikumar/Reuters)

A fireworks display decorates the night sky to celebrate the New Year, as crowds of people look on, at Kim Il Sung Square in Pyongyang, North Korea, early Friday, January 1, 2021. (Photo by Jon Chol Jin/AP Photo)

People wearing face masks to help curb the spread of the coronavirus enjoy a social dance at a public park in Beijing, Tuesday, January 12, 2021. Lockdowns have been expanded and a major political conference postponed in a province next to Beijing that is the scene of China's most serious recent COVID-19 outbreak. (Photo by Andy Wong/AP Photo)