A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. At a rocky outpost in Western Sahara, a new generation of soldiers who have never known war are mobilising as tensions resurface in one of Africa's oldest disputes after a quarter century of uneasy peace. (Photo by Zohra Bensemra/Reuters)

People walk on a sightseeing platform in Zhangjiajie, Hunan Province, China, August 1, 2016. China has opened a 100-metre-long glass skywalk stretching around a cliff on the side of the Tianmen Mountain. The skywalk provides a view of a 300-metre drop and overlooks Tongtian Avenue, a mountain road with 99 turns that snakes up the mountain. When translated in English, it means “Avenue to the Sky”. (Photo by Reuters/Stringer)

Anissa Barbato from New York looks out over the city from the Edge, the highest outdoor sky deck in the Western Hemisphere on September 2, 2020 as it reopened to the public in New York. Rising 1,131 feet in the air from the heart of Hudson Yards it offers 360-degree views of New York Citys iconic skyline from the 100th floor outdoor viewing. (Photo by Timothy A. Clary/AFP Photo)

Indonesia's Mount Sinabung erupts, sending a column of volcanic materials as high as 16,000 feet into the sky on August 10, 2020. The volcano, one of two currently erupting in Indonesia, was dormant for four centuries before exploding in 2010, killing two people. Another eruption in 2014 killed 16 people, while seven died in a 2016 eruption. (Photo by Sutanta Aditya/Abaca/Sipa USA via AP Images)

Chileans watch the sky with special suits prior to a total solar eclipse on July 2, 2019 in Paiguano, Chile. Around 25,0000 tourists arrived to Paiguano, a small town of around 1,000 inhabitants in the Elqui Valley, 650 km away Santiago. This is the only Earth's total solar eclipse of 2019 and the first one since 2017. From this point, the sun will fully disappear for around two minutes. It is best visible from a stripe in the South Pacific, Chile and Argentina. (Photo by Marcelo Hernandez/Getty Images)

A general view shows sculptures made of waste material titled “Trash People” by German Artist HA Schult (unseen), on April 2, 2014 in Ariel Sharon Park, in the suburbs of Tel Aviv. Hundreds of human-size figures constructed from 20 tons of recycled material, including iron, glass, computer parts, cans and more, will dominate the sky line of Tel-Aviv city and be placed in the park. (Photo by Jack Guez/AFP Photo)

The galactic core of the milky way occupied by two small wooden boats on July 2, 2014, in Isle of Wight, UK. The Milky Way shines in mesmerizing colourful patterns above the Isle of Wight in stunning photographs. Chad Powell used a DSLR camera to capture images of the spectacular constellation above the familiar beach scenes of England's largest island. The 22-year-old, who shot the pictures over a year of stargazing on the island, often stayed up until dawn to catch the most dramatic sky-scapes. Chad, a graphic designer from Ventnor, Isle of Wight, used foregrounds of abandoned theme parks, harbors and lighthouses against the illuminated sky. Minor adjustments were made to bring out the contrast and whites in the images. (Photo by Chad Powell/Barcroft Media)

Hot air balloons fly over the sky in Chiang Mai province, northern Thailand, December 6, 2014. The two-day International Balloon festival 2014 featuring balloon pilots from Germany, Spain, Netherlands, Britain, and Czech Republic is held on December 06-07 2014 to celebrate Thai King Bhumibol Adulyadej's 87th birthday and also aimed to promote the tourism industry in Chiang Mai northern city. (Photo by Pongmanat Tasiri/EPA)