“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

Large trumpet vines spread across electrical lines next to a highway in Kinston, N.C., on June 23, 2014. (Photo by Janet S. Carter/Kinston Free Press via AP Photo)

“NASA's Mars rover Opportunity just celebrated its ninth anniversary on Mars – a mission that was originally meant to last just 90 days...” – The Atlantic. Photo: NASA's rover Opportunity visits Victoria Crater, viewed from orbit by the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter in october of 2006. Opportunity is a small dot on the crater's lip, at top right. Opportunity first reached the crater's rim on September 27, 2006. (Photo by NASA/JPL-Caltech/University of Arizona via The Atlantic)

On August 31, 2011, a puppy was rescued from a garbage bag in Central Florida. She was afflicted by a condition dubbed “swimmer puppy syndrome”, formally, pectus excavatum. It's rare in puppies, but when it happens it causes them to lie flat on their chests with their legs perpetually splayed out. It's usually a symptom of serious neurological problems that most puppies cannot survive. Veterinarians recommended putting her to sleep... (Photo by Flyin Fur Pet Photography)

“1955 was a year of change for Marilyn Monroe. After leaving Hollywood for New York, and abandoning her contract with Twentieth Century Fox, Marilyn was no longer “just a dumb blonde”, but a true renegade. In January, Marilyn formed a production company with photographer Milton Greene, and moved into a suite at the Ambassador Hotel”...

Photo: American actress Marilyn Monroe (1926–1962) leans over the balcony of the Ambassador Hotel in March 1955 in New York City, New York. (Photo by Ed Feingersh/Michael Ochs Archives)

Over 30 Douglas C-47 Skytrains (Dakotas) making final preparations for flight formation practice before the 75th D-Day Anniversary flight to Normandy in Duxford, England on June 4, 2019. (Photo by UK Air Force Images)

Northern lights (Aurora borealis) glow brightly over an Inupiaq fish camp along the arctic coast in North Slope, Alaska. (Photo by Steven Kazlowski/Barcroft Media)