A robot is seen on Mount Etna, Italy on July 4, 2017. Mount Etna, in Sicily, is a test bed for the approximately three-foot high, four-wheeled machine ahead of a future mission to the moon. It is being conducted by the German Aerospace Centre, the agency which runs Germany's space programme. (Photo by Antonio Parrinello/Reuters)

Pamukkale, Turkey, is home to these terrace pools, formed by the build-up of carbonate mineral from the warm water flowing from the thermal springs above. (Photo by Image Courtesy of Jennifer Hayes/Getty Images)

A local resident rests on a bench as Mount Bromo volcano erupts in the background in Ngadisari, Probolinggo, East Java, Indonesia January 5, 2016. (Photo by Darren Whiteside/Reuters)

Valentin Arias Delgado and Diana Franco Durango, from Colombia, perform their routine at the Stage style Tango World Championship, in Buenos Aires, Argentina, August 31, 2016. (Photo by Enrique Marcarian/Reuters)

A woman takes a picture with her mobile phone from Caviahue, Neuquen province, Argentina, some 1500 km southwest of Buenos Aires, of the Copahue volcano spewing ashes on December 22, 2012. The authorities of Chile and Argentina issued yellow alerts due to the eruption of the Copahue volcano, placed in the border between both countries. (Photo by Antonio Huglich/AFP Photo)

A Salvadorean clown going by the name of “Almohadita” poses during National Clown Day celebrations at Beethoven Square in San Salvador December 3, 2014. The Salvadorean congress declared the second Wednesday of December as National Clown Day to honour all Salvadorean clowns in their efforts to bring fun to the country, reported local media. (Photo by Jose Cabezas/Reuters)

Participants in traditional dress ride on horseback as they enjoy the atmosphere at the Feria de Abril (April's Fair) on April 12, 2016 in Seville, Spain. The Feria de Abril has a history that dates back to 1857 and takes place a fortnight after Easter each year. The origin of the fair was a cattle market but the event quickly turned its goal from commerce to having fun. More than 1 million local and international participants are expected to attend the Feria de Abril. (Photo by David Ramos/Getty Images)

A man takes a “selfie” with camels at a farm in Taif November 1, 2014. Saudi Arabia said late on Wednesday it had detected six new cases of the deadly Middle East Respiratory Syndrome (MERS) in 24 hours, the biggest daily jump for months with officials blaming lax hospital procedures. Scientists are not sure of the origin of the virus, but several studies have linked it to camels and some experts think it is being passed to humans through close physical contact or through the consumption of camel meat or camel milk. (Photo by Mohamed Alhwaity/Reuters)