A couple dance tango for tourists at Caminito, a touristic hotspot of La Boca neighborhood in Buenos Aires, Argentina, October 15, 2016. (Photo by Enrique Marcarian/Reuters)

This photo of an elephant seal and Gentoo penguin shot by Andrew James in Yankee Harbour, Antarctica. (Photo by Andrew James/Travel Photographer of the Year)

Nic Smith poses to show her body art during the 10th International Tattoo Convention in London September 27, 2014. (Photo by Neil Hall/Reuters)

Aurora Australis from Beerbarrel Beach, by James Stone. Runner Up: Aurorae. (Photo by James Stone/Astronomy Photographer of the Year)

HRP-4C, a five-foot humanoid robot developed at Japan's National Institute of Advanced Industrial Science and Technology, sings and dances with performers at the Digital Contents Expo in Tokyo on October 17, 2010. The robot runs entertainment software called Choreonoid, a name formed from the words “choreograph” and “humanoid”. (Yoshikazu Tsuno/AFP)

Young category winner. Great autumn morning by Fabian Dalpiaz. (Photo by Fabian Dalpiaz/2018 Astronomy Photographer of the Year)

Egyptian bootblacks cleaning a European's shoes in Cairo. (Photo by Hulton Archive/Getty Images). Circa 1870

“I have seen batches of banknotes worth more than $2.6 million, but beyond all doubt, gold bars look much more attractive!”. – Shamil Zhumatov. Photo: Cooling-down gold ingot. March 14, 2013; Tien Shan mountains, Kyrgyzstan. (Photo by Shamil Zhumatov/Reuters)