Pakistani supporters of cricketer-turned politician Imran Khan and Canadian cleric Tahir ul Qadri beat a riot policeman during an anti-government protest in Islamabad on September 1, 2014. Hundreds of protesters trying to topple Pakistan's government briefly seized the state broadcaster on September 1, intensifying the political crisis gripping the nuclear-armed nation. Deadly clashes since the weekend have raised the spectre of military intervention which gained ground after one disillusioned opposition leader said the protesters were acting according to a plan devised by the army. (Photo by Aamir Qureshi/AFP 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)

People watch as an acrobat rides his motorcycle around a circular track at an entertainment park set up outside a shrine in Rawalpindi, Pakistan, on June 19, 2013. (Photo by Muhammed Muheisen/Associated Press)

A giant sinkhole in Guatemala City, on May 31, 2010. More than 94,000 were evacuated as the storm buried homes under mud, swept away a highway bridge near Guatemala City and opened up several sinkholes in the capital. (Photo by Casa Presidencial/Reuters via The Atlantic)

Sinabung mount spews ash to the air during an eruption near from Karo, North Sumatra on January 7, 2014. An Indonesian volcano that has erupted relentlessly for months shot volcanic ash into the air 30 times on January 4, forcing further evacuations with more than 20,000 people now displaced, an official said. (Photo by Sutanta Aditya/AFP Photo)

Yoga students take a class with Nigerian Dwarf goats held by the 'Hello Critter Goat Yoga' team at the Golden Road Pub in Los Angeles, California on May 7, 2018. The goat yoga fitness craze is sweeping the United States with classes now held in pubs, farms and halls across the country. (Photo by Mark Ralston/AFP Photo)

Girls sits on a bench during summer at the Central Park in New York, United States, 2011. (Photo by An Rong Xu)

Daniel Cheong, a dog behaviorist and trainer, steps over a leash as he walks a pack of dogs in Arlington, Va. on November 13, 2018. (Photo by Ricky Carioti/The Washington Post)