This young whooping crane is on its first fall migration, guided by an Operation Migration ultralight aircraft. Each whooper in this population wears an identification band, and many carry tracking devices that record their movements in detail. Joe Duff/Operation Migration USA Inc. hide caption

itoggle caption Joe Duff/Operation Migration USA Inc.

A little chilly for camping: Ice-penetrating radar revealed a mega-canyon below the Greenland ice sheet, extending for more than 460 miles. Courtesy of J. Bamber/University of Bristol hide caption

itoggle caption Courtesy of J. Bamber/University of Bristol

Rock islands dot the ocean in Palau, Micronesia. The waters of the tropical Pacific Ocean have been relatively cool for the last 15 years. Christopher Ward/Corbis hide caption

itoggle caption Christopher Ward/Corbis

At Happy Boy Farms near Santa Cruz, Calif., Early Girl tomatoes are grown using dry-farming methods. The tomatoes have become increasingly popular with chefs and wholesalers. Courtesy Jen Lynne/Happy Boy Farms hide caption

itoggle caption Courtesy Jen Lynne/Happy Boy Farms

An irrigation pivot waters a corn field in Nebraska. Many farmers in Nebraska and Kansas rely on irrigation to water their corn fields. But the underground aquifer they draw from will run dry. Nati Harnik/AP hide caption

itoggle caption Nati Harnik/AP

Marine biologist Stefano Piraino thinks overfishing is one of the reasons jellyfish populations are growing. He said if you take fish out of the oceans, it leaves more food for jellyfish. The jellyfish here are known as Pelagia noctiluca, the mauve stinger. Courtesy of Stefano Piraino/MED-JELLYRISK hide caption

itoggle caption Courtesy of Stefano Piraino/MED-JELLYRISK

Kevin Trenberth is a distinguished senior scientist at the National Center for Atmospheric Research. Rich Crowder/Corbis hide caption

itoggle caption Rich Crowder/Corbis

A Colorado-based firefighter monitors a backfire while battling the Rim Fire in Groveland, Calif., on Thursday. The Rim Fire continues to burn out of control and has grown to more than 105,000 acres, officials said Friday. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images