A pigeon rests on a wild iguana in a tree inside Seminario Park in Guayaquil, Ecuador, Thursday, April 3, 2014. Pigeons coexist with the wild iguanas at this park in the middle of the city surrounded by savannah. (Photo by Dolores Ochoa/AP Photo)

North Korean women in colorful traditional dresses are surrounded by flower blossoms known as “Kimilsungia” as they wait to guide guests at a flower exhibition in Pyongyang, North Korea, April 14, 2014. The flowers, named after Kim Il Sung, are on display to celebrate the late leader's official birth date of April 15, 1912. (Photo by David Guttenfelder/AP Photo)

In this January 27, 2014 photo, snow rollers dot a lot at the northwest corner of Olive and North Main streets in Akron, Ohio. The snow balls are formed naturally when high winds push snow across a hill. (Photo by Michael Chritton/AP Photo/Akron Beacon Journal)

The holder of half a dozen world records will walk across the Grand Canyon on a steel cable with nothing but the Little Colorado River 1,500 feet below on June 23. With no tethers or safety nets, the walk will be the highest tightrope attempt ever for the 34-year-old, at a height taller than the Empire State Building. Last year, Wallenda, a seventh-generation member of the “Flying Wallendas” family of acrobats, became the only person to walk a wire over the brink of Niagara Falls. Photo: Nik Wallenda walks across a tightrope 200 feet above U.S. 41 on January 29, 2013 in Sarasota, Florida. (Photo by Tim Boyles)

“The Curiosity Mars rover has imaged a small metallic-looking protuberance on a rock. Visible (in the image below the green lines point to it), the protuberance appears to have a high albedo and even projects a shadow on the rock below...”

A young exhibitor arrives with her kitten on a lead at the National Cat Club show at Crystal Palace, London. (Photo by Fox Photos/Getty Images). 2nd December 1931

Army soldiers prepare a military elephant for the parade during a rehearsal for Sri Lanka's 68th Independence day celebrations in Colombo, February 2, 2016. (Photo by Dinuka Liyanawatte/Reuters)

In Omdurman, the largest city in Sudan, the Qadiriyya Sufi order meets every Friday outside Sheikh Hamed Al Nil mosque, which houses the tomb of their 19th century Sufi leader. (Photo by Ala Kheir, John Burns and Ibrahim Algrefwi/Brownbook)