The front wheels of a tractor lift off the ground as the driver moves a heavy trailer outside Peshawar, Pakistan February 19, 2018. (Photo by Fayaz Aziz/Reuters)

An alarmed squirrel. (Photo by Mary McGowan/Barcroft Images/Comedy Wildlife Photography Awards)

An emotional former President George Bush, sniffs after touching the flag-draped casket of his father, former President George H.W. Bush, during his State Funeral at the National Cathedral, Wednesday, December 5, 2018, in Washington. (Photo by Andrew Harnik/Pool via Reuters)

A tourist poses for a souvenir snap in front of autumn foliage in Pitlochry, Scotland, Britain on September 28, 2018. (Photo by Russell Cheyne/Reuters)

Fashion models Darien Leigh and Valerie Drew play leap-frog on the beach. 2nd July 1956. (Photo by Harry Kerr). P.S. All pictures are presented in high resolution.

Colonel Roscoe Turner, the pilot of an American Boeing plane, showing his wife a model of the plane, at the airfield in Mildenhall. (Photo by R. Wesley/Fox Photos/Getty Images). 19th October 1934

The waning moon sets behind leafless sumac trees on a crisp, clear morning, Thursday, December 15, 2016, in Portland, Maine. Much of the northern Mid-Atlantic and Northeast will stay cold for the next couple of days as the arctic air remains stuck over the northern Appalachians, the National Weather Service said. (Photo by Robert F. Bukaty/AP Photo)

The Pink Floyd inflatable pig floats next to Broadcasting House to promote their new exhibition at the V&A museum, in London, Britain May 10, 2017. (Photo by Neil Hall/Reuters)