Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge walk hand in hand from Buckingham Palace the day after their wedding to a waiting helicopter as they leave for a secret honeymoon location, on April 30, 2011 in London, England. The marriage of Prince William and Catherine Middleton was led by the Archbishop of Canterbury and was attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding. (Photo by John Stillwell - WPA Pool/Getty Images)

Figures from Antony Gormley's “Field For The British Isles” adorns an exhibition space in St Helen's College in the town of it's creation 15 years ago, June 23, 2008, St Helens, England. The installation of over 40,000 clay figures has returned to the place where it was made by local people from local clay. Artist Antony Gormley describes his creation as “25 tons of clay energised by fire, sensitised by touch and made conscious by being given eyes ... a field of gazes which looks at the observer making him or her its subject”. (Photo by Christopher Furlong/Getty Images)

Model Bianca Gavrilas wears a a hand-embroidered cape made from the silk of the Golden Orb Spider in the V&A Museum's Medieval and Renaissance Gallery on January 23, 2012 in London, England. The cape is one of two golden spider silk textiles that exist in the world, it was made in Madagascar over a period of 8 years and using the silk of silk of 1.2million spiders. (Photo by Oli Scarff/Getty Images)

Owner Nicole Graham works with volunteers from CFA and SES tries to dig out her horse “Astro” who became stuck up to his neck in mud at Avalon Beach on February 26, 2012 in Geelong, Australia. The tide was fast-rising, but the rescuers managed to get him out in time. (Photo by Peter Ristevski/Newspix)

HRP-4C, a five-foot humanoid robot developed at Japan's National Institute of Advanced Industrial Science and Technology, sings and dances with performers at the Digital Contents Expo in Tokyo on October 17, 2010. The robot runs entertainment software called Choreonoid, a name formed from the words “choreograph” and “humanoid”. (Yoshikazu Tsuno/AFP)

A visitor looks at a Morris Mini-Minor Car on display at the Victoria and Albert museums' new major exhibition, “British Design 1948-2012: Innovation In The Modern Age” on March 28, 2012 in London, England. This car, which was designed by Alec Issigonis, was the first one off the production line. The exhibition showcases some of the most iconic product design, fashion, furniture, graphics, architecture and fine art from the last 60 years, and opens to the public from March 31, 2012. (Photo by Dan Kitwood/Getty Images)

“A dirty thunderstorm (also, Volcanic lightning) is a weather phenomenon that occurs when lightning is produced in a volcanic plume. Dirty thunderstorms have been reported in Chile above the Chaiten Volcano, above Alaska's Mount Augustine volcano, and Iceland's Eyjafjallajökull volcano”.

Photo: A cloud of ash pours from Puyehue volcano in southern Chile, at sunset on June 5, 2011. (Claudio Santana/AFP)

Schoolchildren perfom during celebrations to mark 35 years of Zimbabwe's Independence at the National sports stadium in Harare, Saturday, April 18, 2015. President Robert Mugabe, 91, the central figure in Zimbabwean politics 35 years after Independence from Britain, has led the country since 1980. (Photo by Tsvangirayi Mukwazhi/AP Photo)