Participants wear traditional clogs as shepherds lead their sheep through the center of Madrid, October 28, 2012. (Photo by Andres Kudacki/Associated Press)

Mr. Zhong Hua, of Johns Hopkins University School of Medicine, took this image of the peripheral nerves (those outside of the brain) in an 11.5-day-old mouse embryo, magnified five times. (Photo by Zhong Hua)

Women sunbath as Ferrari's Brazilian driver Felipe Massa drives past during the third practice session at the Circuit de Monaco in Monte Carlo on May 25, 2013 ahead of the Monaco Formula One Grand Prix. (Photo by Alexander Klein/AFP Photo)

Groom Praem Pam Srichamnan and his bride Suriya Utai jump into a pond during a wedding ceremony ahead of Valentine's Day in Prachin Buri province, east of Bangkok February 13, 2014. Three Thai couples took part in the wedding ceremony arranged by a resort aimed to strengthen the relationships of the couples by doing fun activities. (Photo by Damir Sagolj/Reuters)

Sikh devotee take part in Nagar Keertan procession on the occasion of Guru Gobind Singh birth anniversary in Allahabad, India on December 29, 2016. Guru Gobind Singh, born Gobind Rai (1666 – 1708), was the 10th Sikh Guru, a spiritual master, warrior, poet and philosopher. When his father, Guru Tegh Bahadur, was beheaded for refusing to convert to Islam, Guru Gobind Singh was formally installed as the leader of the Sikhs at age nine, becoming the last of the living Sikh Gurus. (Photo by Prabhat Kumar Verma/Pacific Press via ZUMA Wire/Rex Features/Shutterstock)

In this January 23, 2015 photo, Guillermo Luna Martinez, 36, carries freshly painted piñatas representing Disney's Frozen snowman character Olaf downstairs to where his wife Elvia Vicente Albarran will use paper to craft the character's eyes, teeth, and distinctive tuft of hair, at the family's workshop in the Iztapalapa neighborhood of Mexico City. Though Luna and his wife have chosen to work in the family business, they plan to let their children, Guillermo, 10, and Melissa, 9, decide for themselves. “Who knows if the business will last forever”, said Luna, “I'd prefer that they study and get a career, for them to have a better future”. (Photo by Rebecca Blackwell/AP Photo)

These stunning color portraits, produced by the U.S. Office of War Information during World War II depict the role of women in the US war effort. All of the images were shot on 4x5 color transparency film by Howard R. Hollem and Alfred T. Palmer during 1942 and 1943 and were turned over to the Library of Congress Prints and Photographs Division in 1944. They are seen here with their original captions.

A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)