New York Police Department tactical police officers stand guard near the New York Stock Exchange on September 9, 2011 in New York City. Officials are stepping up security in New York and Washington D.C. a day after U.S. officials received a credible but unconfirmed terror threat to utilize car bombs on bridges or tunnels in New York or Washington. (Photo by Justin Sullivan/Getty Images)

The Last Bell (we mean the bell that informs the pupils about the beginning or the ending of the lessons) is the traditional feast of the Russian pupils who leave the school. The Last School Bell feast occurs in the end of May, when the school year has already finished, but the final examinations have not begun yet. Luhansk (also known as Lugansk – a city in southeastern Ukraine), 2010. (Photo by X-F@ctor's bloG)

LAPD chopper flies in a foregraund of the Super Moon in Los Angeles, California on May 05, 2012. Tonight's moon is set to appear 14 percent larger and 30 percent brighter from our perspective on Earth. The Supermoon lines up much closely with perigee – the moon's closest point to Earth. The 2012 May full moon falls some six minutes after perigee, the moon's closest point to Earth for this month. At perigee, the moon lies only 221,802 miles (356,955 kilometers ) away. Later this month, on May 19, the moon will swing out to apogee – its farthest point for the month – at 252,555 miles (406,448 kilometers) distant. (Photo by AFP/File, Joe Klamar)

The Photographers 2015 runs from 25 November to 23 December at Osborne Samuel and Beetles+Huxley, London. Here: Untitled, 1950, by Bert Hardy. (Photo by Bert Hardy/Beetles+Huxley & Osborne Samuel)

People gather at the site of a bomb explosion in Sanaa December 23, 2014. Five bombs exploded on Tuesday in Sanaa's old quarter, where many supporters of the Shi'ite Muslim Houthi group live, killing at least one person and wounding another, a Yemeni security official said. No one has claimed responsibility for the attacks, but the Houthis have been fighting the Sunni Islamist militant al Qaeda group and allied tribesmen since its gunmen captured Sanaa in September and forced the resignation of a government they had long seen as corrupt. (Photo by Khaled Abdullah/Reuters)

A photographer has discovered a spectacular way of keeping warm during winter – using fire to heat up icy locations. Sam Scholes uses long-exposures to capture the movement of fire in front of ice-covered backdrops. After lighting steel wool his friend Scott Stringham swings the flaming object in order to make swirling patterns. The result of this technique – captured at Midway Ice Castles in Utah is a vibrant image with the warm light dancing across the cold scenes. (Photo by Sam Scholes/Caters News)

A member of the Community Police of the FUSDEG (United Front for the Security and Development of the State of Guerrero) poses with a weapon during events to mark the first anniversary of the force's operations in Ocotito, January 23, 2015. Based on the traditional indigenous justice system, the Community Police is made up of volunteers from different communities of Guerrero, and was created in response to the spate of violence in several locations in the state. (Photo by Jorge Dan Lopez/Reuters)

A devotee of the Ban Tha Rua Chinese shrine is helped with a spike pierced through her cheeks during a street procession celebrating the annual vegetarian festival in Phuket September 28, 2014. The festival, featuring face-piercing, spirit mediums and strict vegetarianism celebrates the local Chinese community's belief that abstinence from meat and various stimulants during the ninth lunar month of the Chinese calendar will help them obtain good health and peace of mind. (Photo by Damir Sagolj/Reuters)