Couples take part in the “Love and Challenge Marathon” in Hanoi, Vietnam, 16 August 2015. Fifty couples, who are going to get married, participated in the event which is held the fifth time. This year, the winners of the marathon received a honeymoon trip to Malaysia. (Photo by Luong Thai Linh/EPA)

In 1949, LIFE magazine sent famed photographer Nina Leen to document the daily life of a sassy troupe of young women who had run off and joined the famous Barnum & Bailey Circus in Sarasota, Fla. What developed was a portrait of a sisterhood formed over acrobatics that mixed high-flying wire acts with fashionable high-waisted shorts. Sarasota was once considered “the home of the American circus”. Here: an aerialist smoking while rehearsing for the Ringling Bros. and Barnum & Bailey Circus in Sarasota, FL in 1949. (Photo By Nina Leen/Time Life Pictures/Getty Images)

English comic actor and director Charlie Chaplin (Sir Charles Spencer Chaplin, 1889–1977) seated on straw bales during the filming of “The Circus” with his leading lady Merna Kennedy (1908–1944). (Photo by Margaret Chute/Getty Images). 1928

“Are you here for the Winery Tour?” This is a Western Grey Kangaroo caught lounging in the wineries of the Adelaide Hills in South Australia. This past Autumn has been a spectacular time for wildlife viewing and I got lucky to spot this guy while mountain biking in the hills. Such a funny stance it just begs the question... Have you been drinking? ...and or... Are you here for the Winery Tour? Such a spontaneous moment I figured it would be perfect for an entry. I hope you like it! Cheers. Photo location: Adelaide Hills, South Australia, Australia. (Photo and caption by Greg Snell/National Geographic Photo Contest)

UConn students from Storrs, Conn., Gary Tu, Danny Wang and Victor Zheng, fish at Shenipsit Lake in Tolland, Conn. during sunset on Tuesday, August 19, 2014. (Photo by Jim Michaud/AP Photo/Journal Inquirer)

Te Matatini Kapa Haka Aotearoa perform the Haka at the Edinburgh Festival Fringe on the Royal Mile on August 14, 2014 in Edinburgh, Scotland. The largest performing arts festival in the world, this years festival hosts more than 3,000 shows in nearly 300 venues across the city. (Photo by Jeff J. Mitchell/Getty Images)

Typhoon Bopha moves toward the Philippines, observed from the ISS, on December 2, 2012. (Photo by AP Photo/NASA via The Atlantic)

“Himalayan Dog”. This dog just appeared out of nowhere and followed us for an entire week during our trekking trip in the Himalayan outback. He always used to sleep in front of our tent and guarded us in the nights. When I decided to get up at 4 a.m. to climb the next 5000 m peak for sunrise he accompanied me as well. On the top he was sitting for the entire 30 minutes on this place looking straight into the countryside. Photo location: Ladakh, India. (Photo and caption by Sebastian Wahlhuetter/National Geographic Photo Contest)