A rainbow is seen near a cloud south of Corvallis, Ore., Monday, May 19, 2014. (Photo by Andy Cripe/AP Photo/The Corvallis Gazette-Times)

The antennas of the European Southern Observatory's Atacama Large Millimeter/Submillimeter Array, also known as ALMA, are set against the splendor of the Milky Way in this picture by Babak Tafreshi. Construction of the full ALMA array is due to be completed in Chile's Atacama Desert in 2013, but the facility is already making scientific observations with a partial array of antennas. (Photo by ESO/B. Tafreshi/TWAN)

Indian children work nearby to their parents at a construction project in front of the Jawaharlal Nehru Stadium on January 30, 2010 in New Delhi, India. The children accompany their parents to the work site, where if they are prepared to work, they will receive money for bread an milk and be provided with dinner by the contractor. The sheer scale of the project has drawn an enormous population of migrant workers from all over India.

The original costumes for Star Wars character Darth Vader stand on display at “Star Wars: The Exhibition” at County hall on May 04, 2007 in London, England. (Photo by MJ Kim/Getty Images)

A rickshaw driver looks out the windshield as he drives onto the highway in Mardan, Pakistan January 30, 2017. (Photo by Fayaz Aziz/Reuters)

Deers walk past Indonesia's honour guard as they wait for the arrival of Saudi Arabia's King Salman bin Abdul Aziz at the presidential palace in Bogor on March 1, 2017. Cheering crowds welcomed King Salman on March 1 as he began the first visit by a Saudi monarch to Indonesia for almost 50 years, seeking stronger economic ties with the world's most populous Muslim-majority country. (Photo by Adek Berry/AFP Photo)

Stray dogs stand on tombs in Diamond Hill cemetery in Hong Kong, China, 04 April 2017. According to the lunar calendar, the Qingming Festival is observed on 04 April . The Qingming Festival, also known as Tomb-Sweeping Day, is marked by Chinese people by going to the cemetery to cleaning up tombs, bring flowers, and making offerings to their ancestors. (Photo by Jerome Favre/EPA)