The Hubble Space Telescope is shown following its release from the space shuttle Discovery Wednesday, February 19, 1997. The Hubble Space Telescope, one of NASA'S crowning glories, marks its 25th anniversary on Friday, April 24, 2015. With more than 1 million observations, including those of the farthest and oldest galaxies ever beholden by humanity, no man-made satellite has touched as many minds or hearts as Hubble. (Photo by AP Photo/NASA)

A reveller sleeps on the pavement during the Sanja Matsuri festival in the Asakusa district of Tokyo May 17, 2015. The Sanja Matsuri festival attracts over about one million visitors over its duration of three days, when parties of revellers carry portable shrines through the Asakusa neighbourhood, rocking and shaking them in a belief that this intensified the powers of the deities that reside inside them. (Photo by Thomas Peter/Reuters)

Revellers attend the Victorian Picnic during the Wave and Goth festival in Leipzig, Germany, May 22, 2015. The annual festival, known in Germany as Wave-Gotik Treffen (WGT), features over 100 bands and artists in venues all over the city playing Gothic rock and other styles of the dark wave music subculture. One of the biggest of its kind, the event attracts a regular audience of up to 20,000, the organisers said. (Photo by Hannibal Hanschke/Reuters)

A child parades on a float during the Bun Festival on May 25, 2015 in Hong Kong, Hong Kong. One of Hong Kong's most colourful cultural celebration event, Cheung Chau Bun Festival, will be staged on 25 May 2015 (Monday) till 26 May 2015 midnight (Tuesday). This festival has over 100 years of history. Every year, thousands of people descend upon the tiny island for The Piu Sik (Floating Colours) Parade, Lucky Bun (Ping On Bun) and The Bun Scrambling Competition, the ancient custom during the festival. (Photo by Lam Yik Fei/Getty Images)

Revellers take part in the annual “Naval Battle” of Vallecas in Madrid, Spain July 19, 2015. The slogan for this year's water battle is “Get wet for Alfon, freedom for Alfon”, referring to Alfonso Fernandez Ortega, a Vallecas resident who was sentenced to four years in prison in June. The festival was started spontaneously in 1981 when some neighbours started to throw water at one another due to high temperatures during the Virgen del Carmen Festival. (Photo by Juan Medina/Reuters)

A cyclist climbs over a tree fallen atop a car after a heavy storm in Amsterdam, the Netherlands, July 25, 2015. One person was killed as the most severe July storm ever recorded in the Netherlands swept across the country on Saturday, delaying flights and disrupting road and rail traffic. Dozens of flights were delayed at Amsterdam's Schiphol Airport and authorities warned travellers not to take to the road as gale-force winds and rain lashed the country, prompting the meteorological service to issue a “Code Red” warning. (Photo by Cris Toala Olivares/Reuters)

Denis and Nelya, both 30, from Moscow, Russia invited brown bear Stepan along to their very special ceremony. As well as witnessing the couple exchange vows, the bear also played the role of registrar at one point. Denis said: “We both knew Stepan is a very kind bear but still it is a huge, unpredictable animal so we were a bit scared, but still happy to be able to make our dream come true. It was a fantastic experience to have this photoshoot with Stepan”. (Photo by Olga Barantseva/Caters News)

An anti-Gaddafi fighter tests an anti-aircraft gun southwest of Sirte, Libya one of Muammar Gaddafi's last remaining strongholds, September 16, 2011. A timeline of images dating from 2010 from Sirte, Libya, the home town of deposed Libyan leader Muammar Gaddafi. Libyan forces battling Islamic State in the city of Sirte say they have defeated the militant group after months of street to street fighting backed by U.S. air strikes. Islamic State took control of the city more than a year ago and set up its main base outside Syria and Iraq. (Photo by Goran Tomasevic/Reuters)