Viking re-enactors representing the rival armies of the Vikings and Anglo-Saxons skirmish near Clifford’s Tower during the Jorvik Viking Festival on February 23, 2019 in York, England. The annual Jorvik Viking Festival held in York is recognised as the largest event of its kind in Europe. This year the festival remembers the role that the Viking women played during those turbulent times. (Photo by Christopher Thomond/The Guardian)

A woman takes a photo on her mobile phone of a tiger during the media preview of Vivid Sydney at Taronga Zoo on May 19, 2019 in Sydney, Australia. An illuminated trail of almost 300 lit lanterns of endangered species will glow every night at the zoo during Vivid Sydney which runs from May 24 throughout Sydney with hundreds of lit buildings and exhibits which attract hundreds of thousands of visitors each year. (Photo by James D. Morgan/Getty Images)

People march past the Colosseum during the Gay Pride parade in Rome, Saturday, June 11, 2016. Italy joined the rest of Europe last month in giving some legal rights to gay couples after a years-long battle and opposition from the Catholic Church to anything that smacked of authorizing gay marriage. (Photo by Fabio Frustaci/AP Photo)

A visitor walks underneath a replica of a Titanosaur at the Cretaceous park in Cal Orcko, on the outskirts of Sucre, Bolivia, July 22, 2016. A footprint measuring over a meter wide that was made by a meat-eating predator some 80 million years ago has been discovered in Bolivia, one of the largest of its kind ever found. (Photo by David Mercado/Reuters)

Those lights are actually bioluminescent shrimp, better known as sea fireflies, or, in Japan, as “umibotaru”. Visible every year from May until the end of October, they live in the sand around very shallow sea water and are often seen floating between the extremes of high and low tides. Here: Bioluminescent sea fireflies glittering like diamonds on the rocks and sand. Okayama, Japan. July 2016. (Photo by Trevor Williams/Jonathan Galione/Getty Images)

Shepherds walk with sheep through the village on their way home during autumn redyk in Gron, Tatra Mountains region of southern Poland, October 6, 2015. Redyk is a traditional, kilometres-long march of highlanders with flocks of sheep, which takes place twice a year: in the spring at the start of the grazing season, and in the autumn at season's end. (Photo by Kacper Pempel/Reuters)

People use snowshoes during a tour of the Great Kemeri Bog, Latvia, October 17, 2015. The Kemeri bog is more than 8,000 years old and is one of the largest dry moss swamps in the Baltics. A more than decade-long joint restoration of the bog by the European Union and the Latvian government helped the bog recover its high moss marshes, damp black alder forests, floodplain meadows and seaside lakes – features now considered rare in Europe due to industrialisation. (Photo by Ints Kalnins/Reuters)

Deadwood is pictured in the onetime spa and resort town Epecuen, November 5, 2015. Over the past few years the town of Epecuen, located 550 km (341 miles) southwest of Buenos Aires, has been attracting tourists with its eerie apocalyptic atmosphere after a flood submerged it in salt water for more than two decades. Photo by Enrique Marcarian/Reuters)