A PETA (People for the Ethical Treatment of Animals) activist with her body painted promotes veganism in Bangkok April 21, 2016. (Photo by Jorge Silva/Reuters)

The possible surface of TRAPPIST-1f, one of seven newly discovered planets in the TRAPPIST-1 system that scientists using the Spitzer Space Telescope and ground based telescopes have discovered. (Photo by Reuters/NASA/JPL-Caltech)

Two carnival revellers masquerade as Leonardo da Vinci's painting “Mona Lisa” pose in St. Mark's Square in Venice, Italy, Sunday, January 31, 2016. Carnival-goers in Venice are being asked by police to momentarily lift their masks as part of new anti-terrorism measures for the annual festivities. (Photo by Domenico Stinellis/AP Photo)

A Filipino worker arranges roasted pigs which they sell in suburban Quezon city, Philippines on Tuesday, December 23, 2014. Roasted pig is popular during Filipino celebrations and traditionally served during a Christmas eve dinner called “Noche Buena” in this predominantly Roman Catholic nation. (Photo by Aaron Favila/AP Photo)

Two robotic legged squad support system (LS3) machines by the Defense Advanced Research Project Agency follow a technician during a demonstration at Joint Base Myer-Henderson Hall, Virginia, on September 10, 2012. (U.S. Marine Corps photo by Sgt. Mallory S. VanderSchans via The Atlantic)

A woman (C) shops for an offering at the witch doctor's street in La Paz, July 31, 2015. According to Andean culture, the all the month of August is a time to give offerings to “Pachamama” to give thanks for their farms and health. The Aymaras use coca leaves, candies, animal fat, llama fetuses, some dried fruits, powdered minerals and alcohol during these rituals. (Photo by David Mercado/Reuters)

In this September 1, 2015 photo, street artists Jenaro de Rosenzweig, left, and Alejandro Revilla pose for a portrait behind a restaurant's window covered with a mural by artist Francisco Munoz, signed with his artist's name below, in the Roma Norte neighborhood of Mexico City. Rosenzweig and Revilla founded the “Street Art Chilango” cooperative in March 2013, which is filling neighborhoods with public art by local street artists. (Photo by Rebecca Blackwell/AP Photo)