Back dropped by planet Earth the International Space Station (ISS) is seen from NASA space shuttle Endeavour after the station and shuttle began their post-undocking relative separation May 29, 2011 in space. After 20 years, 25 missions and more than 115 million miles in space, NASA space shuttle Endeavour is on the last leg of its final flight to the International Space Station before being retired and donated to the California Science Center in Los Angeles. Capt. Mark E. Kelly, U.S. Rep. Gabrielle Giffords' (D-AZ) husband, has lead mission STS-134 as it delivered the Express Logistics Carrier-3 (ELC-3) and the Alpha Magnetic Spectrometer (AMS-2) to the International Space Station. (Photo by NASA via Getty Images)

A musician from the Rajan Band, Kotla Mubarakpur holds on to a decorated horse as he and others wait prior to performing at a wedding on November 22, 2011 in New Delhi, India. (Photo by Daniel Berehulak/Getty Images)

A woman poses for a photograph during Holi celebrations in the town of Barsana in the state of Uttar Pradesh, India, March 6, 2017. (Photo by Cathal McNaughton/Reuters)

Soldiers pose for a photo during the flower exhibition marking the 105th birth anniversary of the country's founding father, Kim Il Sung in Pyongyang, North Korea April 16, 2017. (Photo by Damir Sagolj/Reuters)

Public Space series, 2015. This series by Morteza Niknahad and Behnam Zakeri tends toward cinema, taking an almost cartoonish view of modern life in Iran. This work was inspired by the social life of dolphins. (Photo by Morteza Niknahad and Behnam Zakeri/The Guardian)

A man carries food supplies on a donkey to Dhalamlam Mountain in the Jafariya district of the western province of Raymah, Yemen June 2, 2016. In villages perched high on a mountain in Western Yemen, residents are a safe distance from a conflict raging throughout most of the country but have had to turn the clock back on their lifestyles by centuries. (Photo by Abduljabbar Zeyad/Reuters)

Children residents take a selfie as they wait for the police to dance, an unconventional approach to connect the police with the community in rough neighbourhoods, as part of the “Tirando Barrio” (Marking territory) programme in Saltillo, Northern Mexico September 9, 2016. T-Shirt reads “Street Dancers”. (Photo by Daniel Becerril/Reuters)