Three secondary schoolboys smoking an illicit cigarette in Hyde Park, London. (Photo by Evening Standard/Getty Images). May 1972

Models showcase Valentine's Day underwear celebrating the results of a recent survey revealing that men find the lingerie, boxer shorts and vests, the biggest turn on ahead of February 14 Valentine celebrations, at Waterloo on February 2, 2006 in London, England. (Photo by Gareth Cattermole/Getty Images)

Mary McHugh mourns her slain fiance Sgt. James Regan at “Section 60” of the Arlington National Cemetery May 27, 2007. Regan, a US Army Ranger, was killed by an IED explosion in Iraq. (Photo by John Moore/Getty Images)

REUTLINGEN, GERMANY - NOVEMBER 17: Students hang out finished parchment leather at the LGR (Lederinstitut Gerberschule Reutlingen) tannery school on November 17, 2010 in Reutlingen, Germany. Even in early antiquity and up their hair or dried goat and sheep skins were used as material for documents. In the small Asian city Pergamon these skins were processed in large quantities for this purpose, so they formed the main trading arm of the city, of which the name is parchment is derived. In medieval times, reached the parchment is of great importance, it was such as France's production under the supervision of the University of Paris. Even now, important documents, placed on their unlimited shelf life as possible large value (eg diplomas, addresses, memory, writings, documents for primary and keystones) written on parchment...

“A small British company with a dream of building a re-usable space plane has won an important endorsement from the European Space Agency (ESA) after completing key tests on its novel engine technology. Reaction Engines Ltd believes its Sabre engine, which would operate like a jet engine in the atmosphere and a rocket in space, could displace rockets for space access and transform air travel by bringing any destination on Earth to no more than four hours away”. – Chris Wickham via Reuters. Photo: Artist's impression of Skylon. (Photo by Reaction Engines Ltd)

A rider on horseback competes in the Margalla Festival Tent Pegging Championship in Islamabad, Pakistan, June 5, 2016. Tent pegging is an equestrian sport popular in India and Pakistan, with a history going back to the cavalries of ancient armies. (Photo by Caren Firouz/Reuters)

A Thai visitor appears to be frightened by a life-size Velociraptor model also known as Raptor at the Dinosaur Planet theme park in Bangkok, Thailand, 25 March 2016. The 500 million baht (14 million US dollars or 12 million euro) theme park opening in the Thai capital aimed to attract more than 15,000 visitors a day featuring a chance to experience more than 200 dinosaurs from various species that are brought back to life. (Photo by Rungroj Yongrit/EPA)

“Diver in Magic Kingdom”. Green Lake (Grüner See) is located Tragöss Austria. In spring snowmelt raises the lake level about 10 meters. This phenomenon, which lasts only a few weeks covering the hiking trails, meadows, trees. The result is magical to watch diving landscapes. Photo location: Grüner See at Tragöss, Austria. (Photo and caption by Marc Henauer/National Geographic Photo Contest)