A police officer gives instructions to migrants rushing to board a train that would take them towards Serbia, at the railway station in the southern Macedonian town of Gevgelija, Wednesday, August 20, 2015. Macedonian police stepped up the security at the border with Greece apparently trying to stem recent surge of migrants who are coming from Greece. (Photo by Darko Vojinovic/AP Photo)

An actor plays an injured passer-by during Exercise Strong Tower, the scene of a mock terror attack at a disused underground station in central London, Britain June 30, 2015. London police held their biggest-ever terrorism drill on Tuesday, pitting the emergency services against a group of marauding attackers, nearly 10 years since four young British Islamists killed 52 people in suicide bombings on London's transport network in July 2005. (Photo by Peter Nicholls/Reuters)

Expedition 44 flight engineer and NASA astronaut Scott Kelly seen inside the Cupola, a special module which provides a 360-degree viewing of the Earth and the International Space Station. Kelly is one of two crew members spending an entire year in space. (Photo by Scott Kelly/NASA)

Ryan Randall plays the bagpipes outside a polling station in Edinburgh, Scotland September 18, 2014. Polling in the referendum on Scottish independence began on Thursday morning, as Scotland votes whether or not to end the 307-year-old union with the rest of the United Kingdom. (Photo by Paul Hackett/Reuters)

Spectators cheer as the United Launch Alliance Delta 4-Heavy rocket, with NASA's Orion spacecraft mounted atop, lifts off from the Air Force Station, December 5, 2014, in Cape Canaveral, Fla. (Photo by Smiley N. Pool/AP Photo/Houston Chronicle)

“For most Londoners, the most common view they enjoy as they trudge to work is the back of another commuter's head. But now, thanks to the Streetmuseum app, anyone traipsing through the capital's streets can step back in time to see what London looked like in the 19th and 20th century compared with today – all in the same image”. – Joe Krishnan via The Independent. Photo: A street scene in London’s Covent Garden with the underground station and a horse and cart in the background in c.1930 and the same street in 2014. (Photo by Museum of London/Streetmuseum app)

Thai officials inspect counterfeit watches before destroying them at Khlongluang Transportation Station in Pathumtani province, on the outskirts of Bangkok April 9, 2015. The counterfeit goods, which included piles of CDs, DVDs, handbags, clothes, brand name shoes, cell phones, caps, glasses, computers, cosmetics and watches are worth over 3.7 billion Thai baht ($ 115,790,901), according to local authorities. (Photo by Chaiwat Subprasom/Reuters)

A merino lamb attempts to jump out of its enclosure to find its mother shortly before feeding time at the Educational and Reserach Station for Animal Breeding (Lehr- und Versuchsanstalt fuer Tierzucht und Tierhaltung, or LVAT) in Brandenburg state on January 27, 2012 in Gross Kreutz, Germany. Hundreds of lambs have been born at the LVAT in recent weeks in the midst of the station's lambing season. Many of the lambs will be sold just before Easter, when they will have grown to a weight of over 40kg, as lamb is the traditional German Easter meal. (Photo by Sean Gallup/Getty Images)