An army tank fires during a firefight against militants linked to al Qaeda near the southern Yemeni city of Zinjibar May 30, 2012. (Photo by Reuters/Yemen's Defence Ministry)

An injured Iraqi Emergency Response Division (ERD) soldier hit by a mortar is held by another officer as they wait for medics to arrive at the Islamic State occupied Mosul Airport in west Mosul, part of the offensive to retake the city some two years after it fell to the hardline jihadist group, February 23, 2017. Iraqi forces encountered stiff resistance with improvised explosives, heavy mortar fire and snipers hampering their advance before they successfully took the airport. (Photo by Martyn Aim/Getty Images)

Max Gold, 20, of NYC, cruises on his skateboard as thousands gather on the National Mall for the March for Science on Saturday, April 22, 2017, in Washington, DC. Activists and scientists descend on the nation's capital to rally for environmental causes and government policies rooted in scientific research as part of the Earth Day and March for Science rallies. (Photo by Jahi Chikwendiu/The Washington Post)

Eagle Prime (MK3), a giant robot by MegaBots Inc. which manufactures giant piloted humanoid fighting robots headquartered in Berkeley, California on October 18, 2017. (Photo by Courtesy Michael Mauldin/Reuters/MegaBots Inc)

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

“A huge wasp measuring 2.5 inches in length, visiting the banana tree in my front yard”. (Photo and comment by John Matzick, USA/2013 Sony World Photography Awards via The Atlantic)

Carlos Melendez prepares to feed his pet squirrel “Colita” in downtown San Salvador January 29, 2015. (Photo by Jose Cabezas/Reuters)

In this Wednesday, July 23, 2014 file photo, Omaha photographer Lane Hickenbottom photographs the night sky in a pasture near Callaway, Neb. With no moon in the sky, the Milky Way was visible to the naked eye. More than one-third of the world’s population can no longer see the Milky Way because of man-made lights, according to a scientific paper by Light Pollution Science and Technology Institute's Fabio Falchi and his team members, published on Friday, June 10, 2016. (Photo by Travis Heying/The Wichita Eagle via AP Photo)