One of the negatives discovered by Rick Norsigian. Courtesy Rick Norsigian hide caption

itoggle caption Courtesy Rick Norsigian

Oil burns at the Ixtoc 1 offshore drilling rig in December 1979. The rig dumped 140 million gallons of crude oil into the Gulf of Mexico and covered about 170 miles of the South Texas coast, including Galveston. John Hoagland/Liaison/Getty Images hide caption

itoggle caption John Hoagland/Liaison/Getty Images

A group of teenagers take a morning jog at the Wellspring Academy in Reedley, Calif., in 2009. The school specializes in helping teens and college students lose weight. A new study shows teens who remain obese risk a lifetime of chronic health problems and poverty. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

A flint-knapper makes sharp stone flakes by striking a flint "core" with a hammerstone. Human Origins Initiative hide caption

itoggle caption Human Origins Initiative

The rafting industry is a key economic driver in many rural towns in Colorado. Ed Andrieski, File/AP hide caption

itoggle caption Ed Andrieski, File/AP

When Jennifer Jones Austin was unable to find a bone marrow donor match, her family appealed to the public in ads shown in churches and on the Internet. Courtesy of The ICLA Da Silva Foundation hide caption

itoggle caption Courtesy of The ICLA Da Silva Foundation

Alex Williamson, 8, is one of 17 million children who live in U.S. households where getting enough food is a challenge. Sometimes it's hard for the poor to eat healthy because it costs more. Pam Fessler/NPR hide caption

itoggle caption Pam Fessler/NPR

Brian and Kendra Cosom want to make their marriage last. Coburn Dukehart/NPR hide caption

itoggle caption Coburn Dukehart/NPR