A composite self-portrait of the Mars Pathfinder. NASA/JPL hide caption

Part of the cover art for Planetarium, the concept album by Nico Muhly, Sufjan Stevens, James McAlister and Bryce Dessner. Courtesy of the artist hide caption

Shawn Sheehan, Oklahoma's 2016 Teacher of the Year, sits in his classroom one last time before moving to Texas for better pay. Emily Wendler/KOSU hide caption

A new urban district and an annual big-data expo have arisen in recent years as the centerpiece of the high-tech industry in Guiyang, capital of Guizhou province. Anthony Kuhn/NPR hide caption

Mike Bento (center), an organizer with NYC Shut It Down, leads a march in honor of a black transgender person who was recently killed in New York City. Hansi Lo Wang/NPR hide caption

A lightning strike caused a wildfire that consumed more than 6,500 acres in the Great Dismal Swamp National Wildlife Refuge in August 2011. Swamp fires like this often burn for months because of the dry peat soil. Greg Sanders/U.S. Fish and Wildlife Service hide caption

A group of men with full glasses proudly pose with their keg of beer in San Francisco, 1895. Underwood Archives/Getty Images hide caption