A security guard walks past a giant Doctor Who poster at the “Doctor Who 50th Celebration” event in the ExCeL centre on November 22, 2013 in London, England. The sold-out three day event in the ExCeL London convention centre celebrates 50 years of the show which has seen 11 actors play the role of Doctor Who and receives a worldwide cult following. (Photo by Oli Scarff/Getty Images)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

Wayne McMahon from “The Wolfhound Experience” walking alongside four Irish Wolfhounds: Connell, Mac, Brendan, and Barra, accompanied by an Irish Terrier Lady MacBeth, at St. Stephen's Green in Dublin, Ireland, on May 16, 2024. The Wolfhound Experience offers a one-hour walking tour in Dublin's St. Stephens' Green, where visitors can meet and learn about Irish Wolfhounds, the gentle giants of the canine world. (Photo by Artur Widak/NurPhoto/Rex Features/Shutterstock)

The twin lighthouses of St Joseph on Lake Michigan have been transformed by a winter storm. Ice encases the buildings, giant icicles hang from the piers and the beach is frosted white. Here: Huge icicles hang from the pier. (Photo by Mike Kline/Barcroft Media)

The world's biggest copy of the Mona Lisa is unveiled on October 28, 2009 in Wrexham, Wales The giant version of Leonardo da Vinci's masterpiece measures 17.5 metres across and is 50 times bigger than the original painting and was created by community groups in Wrexham and artist Katy Webster. (Photo by Christopher Furlong/Getty Images)

A giant size figure of the United States' goalkeeper Tim Howard is displayed outside a shopping mall in Hong Kong, Thursday, June 12, 2014, to promote the upcoming 2014 World Cup in Brazil. A total of seven 3.5 meters to 4 meters (11 feet 6 inch to 13 feet one inch) tall figures of famous players attract many soccer fans. (Photo by Vincent Yu/AP Photo)

This image is NGC 6543 known as the Cat's Eye Nebula as it appears to the Chandra X-Ray Observatory and Hubble Telescope. A planetary nebula is a phase of stellar evolution that the sun should experience several billion years from now, when it expands to become a red giant and then sheds most of its outer layers, leaving behind a hot core that contracts to form a dense white dwarf star. This image was released October 10, 2012. (Photo by J. Kastner/NASA/CXC/RIT)

NASA's Cassini spacecraft has provided scientists the first close-up, visible-light views of a behemoth hurricane swirling around Saturn's north pole. In high-resolution pictures and video, scientists see the hurricane's eye is about 1,250 miles (2,000 kilometers) wide, 20 times larger than the average hurricane eye on Earth. Thin, bright clouds at the outer edge of the hurricane are traveling 330 mph(150 meters per second). The hurricane swirls inside a large, mysterious, six-sided weather pattern known as the hexagon. Photo: The spinning vortex of Saturn's north polar storm resembles a deep red rose of giant proportions surrounded by green foliage in this false-color image from NASA's Cassini spacecraft. (Photo by NASA/JPL-Caltech/SSI)