A tourist walks inside the Ice Palace glacier hollow at Hintertux glacier, located at around 3250 meters above sea level, in Zillertal, Austria, 02 March, 2016. The hollow's temperature remains constant at 0 degrees Celsius, in summer and winter alike, and is also used by the University of Innsbruck for scientific research projects. (Photo by Lisi Niesner/EPA)

In this May 4, 2014 photo, a miner holds an amalgam of mercury and gold he mined after working a 28-hour shift at an illegal gold mining process, in La Pampa, in Peru's Madre de Dios region. Thousands of artisanal gold miners sweat through the long shifts and endure, for a few grams of gold, the perils of collapsing earth, limb-crushing machinery and the toxic mercury used to bind gold flecks. (Photo by Rodrigo Abd/AP Photo)

The shadow of a partial eclipse is cast on to the cheek of a student on the roof of the Jana Dlugosza Academy in Czestochowa, Poland March 20, 2015. (Photo by Grzegorz Skowronek/Reuters/Agencja Gazeta)

These friends took a tumble after sharing a hug in Leeds in northern England on May 17, 2021, as Covid-19 lockdown restrictions ease. (Photo by London News Pictures)

Ballet dancer Anoushka Zoe James dances in the water at the Ipanema beach in Rio de Janeiro, Brazil on October 29, 2020. (Photo by Pilar Olivares/Reuters)

Dutch driver Hans Jos Liefhebber on his KTM drives next to a seal during the fifth stage of the 2018 Dakar Rally, between San Juan de Marcona and Arequipa, on the beach of Puerto Lomas, Peru, 10 January 2018. The 2018 Dakar says goodbye to the dunes with its fifth and final stage over the Peruvian desert and begins to take height as it enters the Andean mountain range, heading for Bolivia. (Photo by David Fernandez/EPA/EFE)

A staff member demonstrates how she puts on the helmet of a mock space suit at the C-Space Project Mars simulation base in the Gobi Desert outside Jinchang, Gansu Province, China, April 17, 2019. The facility – comprising several interconnected modules including a greenhouse and a mock decompression chamber – opened its doors to the public. (Photo by Thomas Peter/Reuters)

“A Mothers Tail”. A baby cub pulls on his mother's tail to get attention. Photo location: Masai Mara, Kenya. (Photo and caption by Tori Marsh/National Geographic Photo Contest)