The Ivanpah Solar Electric Generating System is seen in an aerial view on February 20, 2014 in the Mojave Desert in California near Primm, Nevada. The largest solar thermal power-tower system in the world, owned by NRG Energy, Google and BrightSource Energy, opened last week in the Ivanpah Dry Lake and uses 347,000 computer-controlled mirrors to focus sunlight onto boilers on top of three 459-foot towers, where water is heated to produce steam to power turbines providing power to more than 140,000 California homes. (Photo by Ethan Miller/Getty Images)

A woman lays dead outside the Redemption Hospital on Saturday September 20, 2014 in Monrovia, Liberia. Ebola patients come to the hospital, which has become a transfer and holding center to intake Ebola patients, but there is no space and some die while waiting outside. Redemption is located in one of the poorest neighborhoods of Monrovia that locals call "New Kru Town”. Health workers are overwhelmed with a constant stream of new patients since the Ebola outbreak. (Photo by Michel du Cille/The Washington Post)

Students from St Andrew's University indulge in a tradition of covering themselves with foam to honour the “academic family” on October 20, 2014, in St Andrews, Scotland. Every November the “raisin weekend” which is held in the university's Lower College Lawn, is celebrated and a gift of raisins (now foam) is traditionally given by first year students to their elders as a thank you for their guidance and in exchange they receive a receipt in Latin. (Photo by Jeff J. Mitchell/Getty Images)

A full moon rises behind Glastonbury Tor as people gather to celebrate the summer solstice on June 20, 2016 in Somerset, England. Tonight's strawberry moon, a name given to the full moon in June by Native Americans because it marks the beginning of strawberry picking season, last occurred on the solstice on June 22, 1967 and it will not happen again on the summer solstice for another 46 years until June 21, 2062. (Photo by Matt Cardy/Getty Images)

People watch a crocodile with a used motorcycle tyre around its neck on a river in Palu, Central Sulawesi province, Indonesia September 20, 2016 in this picture taken by Antara Foto. Residents suspect the tyre was garbage thrown into the river before it became trapped around the crocodile's neck, reported Antara. (Photo by Mohamad Hamzah/Reuters/Antara Foto)

In this Monday, July 20, 2015 photo, Bill Lattin, the Southern California Timing Association president and Speed Week race director, stands in the Bonneville Salt Flats in Utah. A small city of tents, trailers and thousands of visitors appears almost every August in the Utah desert to watch cars, motorcycles and anything with wheels rocket across gleaming white sheets of salt at speeds of 400 mph. But wet weather has forced the cancellation of Speed Week for the second straight year and revived a debate about whether nearby mining is depleting the Bonneville Salt Flats of their precious resource. (Photo by Rick Bowmer/AP Photo)

Rougine, a 19-year-old female Arab fighter among the Syrian Democratic Forces, made up of US-backed Kurdish and Arab fighters, stands in fatigues embracing another colleague near the village of al-Torshan, 20 km on the outskirts of Raqa on February 6, 2017. (Photo by Delil Souleiman/AFP Photo)

Riot police officers in position to crack down on demonstrators during a protest against Venezuelan President Nicolas Maduro, in Caracas on April 20, 2017. Venezuelan riot police fired tear gas Thursday at groups of protesters seeking to oust President Nicolas Maduro, who have vowed new mass marches after a day of deadly unrest. Police in western Caracas broke up scores of opposition protesters trying to join a larger march, though there was no immediate repeat of Wednesday's violent clashes, which left three people dead. (Photo by Juan Barreto/AFP Photo)