Four pillars of light from the 4 Laser Guide Star Facility on ESO's Very Large Telescope (VLT) are shown reaching into the Chilean night sky in this image from ESO Photo Ambassador Fred Kamphues, on September 2, 2016. The lasers are a key part of the adaptive optics system on the VLT. Adaptive optics allows astronomers to drastically reduce the atmospheric distortion present at even the best sites in the world for astronomy, including Paranal in Chile, the home of the VLT. (Photo by F. Kamphues/ESO)

Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

A Nepalese vetinary and technical team release a rhino after it is relocated in Chitwan National Park some of 250 Kilometer South of Kathmandu on April 4, 2017. Conservationists on April 3 captured a rare one-horned rhinoceros in Nepal as part of an attempt to increase the number of the vulnerable animals, which are prized by wildlife poachers. Five rhinos – one male and four female – will be released into a national park in Nepal's far west over the coming week in the hope of establishing a new breeding group. (Photo by Prakash Mathema/AFP Photo)

An Israeli soldier takes part in during a rehearsal for a ceremony to mark Israel's Memorial Day for fallen soldiers at the Mount of Olives cemetery in east Jerusalem, Tuesday, May 10, 2016. Israel will mark the annual Memorial Day in remembrance of soldiers who died in the nation's conflicts, beginning at dusk Tuesday until Wednesday evening. (Photo by Oded Balilty/AP Photo)

Female Naval Academy plebes perform push ups with a twelve foot log on top of them during the annual Sea Trials May 17, 2016 at the Naval Academy in Annapolis, Maryland. The Naval Academy freshman class endures 14 hours of rigorous physical and mental challenges during the annual Sea Trials training exercise as part of the culmination of their freshman year at the academy. (Photo by Win McNamee/Getty Images)

Tourists dressed in yukatas, a light, unlined, summer kimono made of cotton instead of the traditional silk, climb steps to visit a temple on April 27, 2016 in Kyoto, Japan. Now the seventh largest city in Japan, Kyoto was once the Imperial capital for more than one thousand years, it is now the capital city of Kyoto Prefecture and a major part of the Kyoto-Osaka-Kobe metropolitan area. (Photo by Carl Court/Getty Images)

South Korean rescue members wearing chemical protective suits walk past a monster character (R) during an anti-terror drill as part of a disaster management exercise at the COEX shopping and exhibition center in Seoul on May 20, 2016. South Korea is holding its 2016 Safe Korea anti-disaster exercise this week against terrorist threats and natural disasters. (Photo by Jung Yeon-Je/AFP Photo)

Iraqi pro-government forces fire an anti-tank cannon near al-Sejar village, north-east of Fallujah, on May 25, 2016, as they take part in a major assault to retake the city from the Islamic State (IS) group. Iraqi forces, consisting of special forces, soldiers, police, paramilitary-fighters and pro-government tribesmen, launched a major assault to retake Fallujah, the scene of deadly battles during the US occupation and one of the toughest targets yet in Baghdad's war on the Islamic State group. (Photo by Ahmad Al-Rubaye/AFP Photo)