“A Mothers Tail”. A baby cub pulls on his mother's tail to get attention. Photo location: Masai Mara, Kenya. (Photo and caption by Tori Marsh/National Geographic Photo Contest)

A hillside erupts in flame as a raging wildfire fire burns in Placerita Canyon in Santa Clarita, Calif., Monday, July 25, 2016. A raging wildfire that forced thousands from their homes on the edge of Los Angeles continued to burn out of control Monday as frustrated fire officials said residents reluctant to heed evacuation orders made conditions more dangerous and destructive for their neighbors. (Photo by Nick Ut/AP Photo)

Dayane Mello attends the photocall for the television miniseries “The Young Pope” at the 73rd Venice Film Festival in Venice, Italy, September 3, 2016. (Photo by Alessandro Bianchi/Reuters)

Girls play in the water during the Balaton Sound music festival held on the shore of lake Balaton in Zamardi, west Hungary, on July 9, 2017. (Photo by Sandor Csudai/Rockstar Photographers)

A woman transports fodder for her cattle on a bullock cart on the outskirts of Ajmer, Rajasthan, January 6, 2017. (Photo by Himanshu Sharma/Reuters)

A woman takes part in a “Brave Run” competition in Minsk October 4, 2015. (Photo by Vasily Fedosenko/Reuters)

An undated handout picture made available on 29 April 2016 by the Toronga Zoo shows a baby echidna making a remarkable recovery after being attacked by chickens in a family's backyard at the Taronga Zoo in Sydney, Australia. (Photo by EPA/Taronga Zoo)

Google's vice president Alan Eustace looks out of his spacesuit into the stratosphere prior to a record-breaking skydive over New Mexico, in this still image taken from video October 24, 2014, a handout courtesy of the Paragon Space Development Corporation. Eustace was lifted up 135,890 ft (41,420 metres) by an enormous balloon while wearing a specially designed pressurized space suit, the Paragon Space Development Corporation said. Eustace remained in a free fall for approximately 4.5 minutes before landing safely nearly 70 miles (43.4 kms) from his launch point, setting a world record for the highest skydive and breaking the sound barrier in the process. Eustace landed safely on the ground just 15 minutes after he was lifted into the air. (Photo by Reuters/Paragon Space Development Corporation)