A weeping South Vietnamese mother and her three children are shown on the deck of this amphibious command ship being plucked out of Saigon by U.S. Marine helicopters in Vietnam, April 29, 1975. (Photo by AP Photo)

A handout picture provided by Solar Impulse on 18 March 2015 shows the Swiss solar-powered plane Solar Impulse 2, HB-SIB, taking off with Swiss explorer Andre Borshberg on board for the third leg Ahmedabad to Varanasi, of the Round-The-World, in Ahmedabad, India, 18 March 2015. Swiss explorers Bertrand Piccard and Andre Borschberg attempt to circumnavigate the world flying with an aircraft, with a 72 metres wingspan, powered only by solar energy without a drop of fuel. (Photo by EPA/Solar Impulse)

A photo provided by the Atlanta Journal-Constitution shows Atlanta police officer T. R. Coxe removing painted material of a large swastika featuring a likeness of Republican presidential candidate, Donald Trump, along the northbound Buford Highway Connector just south of the Piedmont exit, in Atlanta, Georgia, USA, 09 December 2015. Just days after Donald Trump's call to ban Muslims from entering the United States, someone painted large swastikas featuring the Republican presidential candidate's face on at least two northeast Atlanta bridge supports. The symbol, which includes a cartoon of Trump sporting a Hitler-like mustache, was painted along the Buford Highway Connector. A second, similar image was found on a concrete bridge support on nearby Piedmont Road. Trump said in a statement released on 07 December that there should be a total and complete shutdown of Muslims entering the United States. (Photo by John Spink/EPA/AJC)

U.S. Rep Steve Southerland grins after winning an auctioned possum during the Wausau Possum Festival on Saturday, August 2, 2014, in Wausau, Fla. What is usually a must-attend event for statewide candidates was notably lacking of them this year, perhaps because candidates who now raise tens of millions of dollars focus more on television ads than making personal contact. But not attending is a missed opportunity, said Susan MacManus, a University of South Florida political science professor who drove more than 350 miles for the festival. (Photo by Heather Leiphart/AP Photo/The News Herald)

“Hiding In The Shadows”. This Baby Sandhill taking refuge under Moms wings while sitting on her second egg. I witnessed this baby being born earlier that day,and the next morning saw the other one hatch,what a sight to see. Photo location: Deland, Florida. (Photo and caption by Scott Helfrich/National Geographic Photo Contest)

“One in Eight Hundred” by Mario Wezel, from Germany, is the winner of the “People” category. The title refers to the odds given to Martin and Karina at their prenatal screening before their daughter, Emmy, was born. The five-year-old from Denmark has Down's Syndrome. (Photo by Mario Wezel/Sony World Photography Awards)

A worker walks through a salt pan on the eve of May Day or Labour Day on the outskirts of the southern Indian city of Chennai April 30, 2014. India is the third largest salt producing country in the world after China and U.S. with global annual production about 230 million tonnes, according to government data. (Photo by Reuters/Babu)

In this February 19, 2017 photo, a couple dances during the “If you don't give me....then you lend me” Carnival street party on Ipanema beach, in Rio de Janeiro, Brazil. The typical view of Carnival in Brazil is anything goes, with no headdress too big, no outfit too small, no song too ribald, but this year some organizers of the world's best known party are drawing the line at lyrics that are sexist, homophobic or racist. (Photo by Silvia Izquierdo/AP Photo)