Luis Hernan was always curious about how wireless technologies like radio are transmitted through the air. So after finishing up his studies in architecture, computer science, and design, Hernan decided to research these invisible signals through a PhD at Newcastle University. Hernan set up a system that turned the wireless signals around him into colourful, ghostlike images using long-exposure photography, allowing people to see the strength of the signals around them. (Photo by Luis Hernan)

Yaroslav Segeda at the top of a high rise building in Kudrinskaya Square, Moscow, Russia. (Photo by Yaroslav Segeda/Caters News)

Roof-topping enthusiast Daniel Lau takes a selfie with high-rise buildings down below as he stands on the top of a skyscraper in Hong Kong, China on August 15, 2017. A craze that began in Russia has now taken hold in Hong Kong, one of the world's most vertical cities. Mr Lau said he had been inspired by Russian climbers and that he was unafraid of the vertiginous heights he scales. (Photo by ImagineChina/Rex Features/Shutterstock)

“Michael Jackson, the performer, consistently transcended racial and gender perceptions; Michael Jackson tribute artists, impersonators and lookalikes reflect this in that they embody a wide span of inspiration and intention. The current crop of impersonators are people who take great care in their appearance – some spend a lot of money and time on their make up and clothing, while others are more concerned with the physical gestures associated with his dances while expressing very little concern in the creation of an illusion”. – Lorena Turner. (Photo and caption by Lorena Turner)

Muslims pray at the top of Mount Al-Noor during their Umrah Mawlid al-Nabawi “Birthday of Prophet Mohammad” in the holy city of Mecca, Saudi Arabia January 16, 2016. Muslims believe Prophet Mohammad received the first words of the Koran through Gabriel, at the top of Mount Al-Noor in the holy city of Mecca. (Photo by Amr Abdallah Dalsh/Reuters)

A man sits on top of a car as he is stranded on a flooded street in Tianjin, China, July 20, 2016. (Photo by Reuters/Stringer)

Battersea Power Station. The chimney rims are thinner on top than you might expect. (Photo by Bradley L. Garrett)

Children play on top of an old plane's fuselage at a dump site in Paranaque city, Metro Manila, Philippines January 21, 2017. (Photo by Ezra Acayan/Reuters)