A polar bear fast asleep at London Zoo. (Photo by Fox Photos/Getty Images). 1961

A steam traction engine with a broken rear axle in Pall Mall, London. (Photo by Topical Press Agency/Getty Images). November 1923

A horse smiles at the camera. See the beautiful images of horses gleefully playing in Iceland mountain ranges. The horses have been spotted smiling and cuddling in remote locations across the nation. (Photo by Bragi J. Ingibergsson/Caters News)

This 2014 series Shanghai Tian Wa saw Chinese photographer Liu Tao train his lens on two distinct districts in Shanghai. Here: “Shanghai Tian Wai №26, 2014”. (Photo by Liu Tao/The Guardian)

The CBRE Urban Photographer of the Year competition – now in its ninth year – encourages professional and amateur photographers to capture cities at work. Here: Dog Walker – 15:00. The competition allows photographers to enter up to 24 images, one representing each hour of the day. (Photo by Johanna Siegmann)

A giant storm cloud can be seen in the sky above swimmers near Mollymook Beach, south of Sydney, March 5, 2014. (Photo by David Gray/Reuters)

In this image provided by the Pairi Daiza park, giant panda Hao Hao holds her newborn baby in her mouth at the park in Brugelette, Belgium, on Thursday, June 2, 2016. With the help of the Chinese government Hao Hao and her mate Xing Hui arrived in Belgium two years ago and Pairi Daiza adapted its park to build a bamboo forest for them. (Photo by Benoit Bouchez/Pairi Daiza via AP Photo)

A man takes a picture of models as they pose next to Cosmis Racing Wheels products during the 2016 Moscow International Auto Salon in Moscow, Russia, August 26, 2016. (Photo by Sergei Karpukhin/Reuters)