A man walks his dog as the sun sets in a park in Frankfurt, Germany, Monday, September 18, 2017. Cool damp weather is set to continue in this part of Germany for the next few days with temperatures in the mid teens Celsius. (Photo by Michael Probst/AP Photo)

Young children at a Bristol, Great Britain health centre unsure of the benefits of sun-lamps and the special glasses that must be worn, July 1948. The health centre was part of the newly introduced free National Health Service. (Photo by Popperfoto/Getty Images)

In this photo taken on Thursday, March 7, 2019, the sun rises over the star on the spire on top of a Stalin-era skyscraper, now the Radisson Royal Hotel on the banks of the Moskva River in Moscow, Russia. (Photo by Dmitry Serebryakov/AP Photo)

A Aldabra Tortoise receives a Christmas treat at Taronga Zoo on December 14, 2012 in Sydney, Australia. Taronga Zoo celebrated Christmas early giving Christmas-themed environmental activities to the Zoo's Giraffes, Sun Bears, Meerkats, Aldabra Tortoise and Cockatoos providing a wonderful natural display for Zoo visitors. (Photo by Lisa Maree Williams)

UFC women's bantamweight champion Holly Holm and Miesha Tate face off during the UFC 196 weigh ins at the MGM Grand Garden Arena in Las Vegas on Friday, March 4, 2016. (Photo by L.E. Baskow/Las Vegas Sun via AP Photo)

These pictures show the beautiful ruins of abandoned temples. The incredible shots, taken at temples in Angkor, Cambodia, show the striking yet haunting temples as they crumble to ruins. While they may have lost some of their former glory, the stunning temples show the beauty of the Cambodian landscape through the historic architecture. Here: Sun rises over the 5 towers of Angkor. (Photo by Alex Teuscher/Caters News)

An elderly man uses a fan to shade himself from the sun as he walks in a public park in Beijing, Tuesday, June 7, 2016. Thursday marks the Duanwu Festival, a public holiday in China celebrated with outdoor activities including dragon boat races. (Photo by Mark Schiefelbein/AP Photo)

As the sun sets on the Malecon in Havana on Friday January 23, 2015, Surenis Angulo de la Paz, 24, center, dances as group of locals play music around her. Behind her is Fidel Lopez, 55. (Photo by Sarah L. Voisin/The Washington Post)