In this photo taken on July 19, 2014, a man looks at an excavation as an A.R.M.H., Association for the Recovery of Historical Memory, volunteer digs on the search for the body of Perfecto de Dios, in a hidden grave in Chaherrero, Spain. Across Spain, volunteer teams of archeologists, anthropologists and forensic scientists head out every year on expeditions to dig for suspected mass graves – a legacy of Spain's fascist past during the time of General Francisco Franco. (Photo by Daniel Ochoa de Olza/AP Photo)

An infrared portrait from NASA's Spitzer Space Telescope which shows generations of stars is seen in this undated NASA handout image released February 14, 2013. In this wispy star-forming region, called W5, the oldest stars can be seen as blue dots in the centers of the two hollow cavities (other blue dots are background and foreground stars not associated with the region). Red shows heated dust that pervades the region's cavities, while green highlights dense clouds. (Photo by NASA/Reuters/JPL-Caltech/Harvard-Smithsonian/Handout)

“Gangnam Style” star PSY's new music video had been watched more than 10 million times on YouTube less than 24 hours after he unveiled his much-anticipated new dance in Seoul, the website showed Sunday. Photo: PSY performs at his concert “Happening” in Seoul, on April 13, 2013. The South Korean pop star's first new single since his viral hit “Gangnam Style” is stealing attention from inter-Korean tensions. (Photo by Kin Cheung/Associated Press)

A three-month-old Sumatran tiger cub named “Bandar” shows his displeasure after being dunked in the tiger exhibit moat for a swim reliability test at the National Zoo in Washington, on November 6, 2013. All cubs born at the zoo must take a swim test before being allowed to roam in the exhibit. Bandar passed his test. (Photo by Manuel Balce Ceneta/Associated Press)

In this Tuesday, February 11, 2014, photo, a trained monkey, that makes a living for her Pakistani owner by performing to a crowd in public and private places, sits held by a leash, in Rawalpindi, Pakistan. For Pakistanis who raise and train the monkeys they are an important source of income in an impoverished country, and they form a strong bond with the animals. The monkeys are usually captured in the wild when they are babies and then trained. A trained monkey can fetch 20,000 to 30,000 rupees ($190 to $285). (Photo by Muhammed Muheisen/Associated Press)

“Magician David Blaine's latest stunt boasts lots of high-voltage snap, crackle and pop – but experts say he'll be safe from electrocution as long as he wears his chain-mail suit and metal headgear”. – NBC News. Photo: Blaine stands inside the apparatus, surrounded by a million volts of electric currents streamed by tesla coils. The stunt, sponsored by Intel, is the latest of daredevil endeavors by the magician whose previous stunts included being encased in ice for over 60 hours in Times Square, on October 5, 2012. (Photo by John Minchillo/Associated Press)

A shooting star (L, top) is seen on the night sky during the perseid meteor shower in Jankowo, near Poznan, 11 August 2016. The first half of August is traditionally the best time to look out for meteors called “shooting stars”, or perseids which are the leftover dust particles of a comet tail associated with comet Swift-Tuttle. (Photo by Lukasz Ogrodowczyk/EPA)

Participants dressed in historical clothing ride high-wheel bicycles during a bicycle ballet event at Schloss Karlsruhe palace during the 2017 International Veteran Cycle Association (IVCA) rally to celebrate the 200th anniversary of the bicycle on May 27, 2017 in Karlsruhe, Germany. Karl Drais, a German inventor, built and tested the first bicycle, called the Draisine, that ran without pedals in 1817. (Photo by Alexander Scheuber/Getty Images)