An artist's concept shows a NASA Mars exploration rover on the surface of Mars. The twin rovers Spirit and Opportunity were launched in 2003 and arrived at sites on Mars in January 2004. NASA/JPL-Caltech hide caption

Most American cars run on gasoline. But analysts say that's poised to change as electric vehicles take over the market, although they disagree on how soon. Johannes Eisele/AFP/Getty Images hide caption

An American coot flies over Brooklyn's Prospect Park Lake on Feb. 5. Courtesy of August Davidson-Onsgard hide caption

A picture taken on Feb. 8, 2019 shows the signature "AHitler" on a watercolor entitled "Im Wald" (In the forest) displayed at the Weidler auction house in the southern city of Nuremberg. Daniel Karmann/AFP/Getty Images hide caption

Measles is a highly contagious illness that can cause serious health problems, including brain damage, deafness and, in rare cases, death. Vaccination can prevent measles infections. Eric Risberg/AP hide caption

The Netflix series Travelers uses video footage from an oil train disaster in Lac-Megantic, Quebec for its fictional series about time-travelers. The use of the footage has angered Canadians. Netflix/Screenshot by NPR hide caption

A boy holds the burqa of his mother as they walk down a street in the old city of Kabul on November 1, 2009. Nicolas Asfouri/AFP/Getty Images hide caption

Mahmud, 11, Ayyub, 7, and their mother, Felicia Perkins-Ferreira, walk toward the boat that will take them out of Syria, across the river to Iraq, so they can start their journey home to Trinidad. Ruth Sherlock/NPR hide caption

A portrait of the Brooklyn Dodgers' infielder Jackie Robinson in uniform circa 1945. Hulton Archive/Getty Images hide caption

Michelle Sherman found an unexpected LGBT ally when she came out — her 93-year-old grandmother, Alice Palmer. Michelle Sherman/NPR hide caption

People wait in line at Chef Jose Andres' World Central Kitchen for free meals to workers affected by the government shutdown in Washington, DC. Pablo Martinez Monsivais/AP hide caption

Lisa Abramson holds her firstborn child, Lucy, in 2014. A few weeks after Lucy's birth, Abramson began feeling confused and then started developing delusions — symptoms of postpartum psychosis. Courtesy of Claire Mulkey hide caption

Belmont University's nursing program started hiring actors like Vickie James to help with their end-of-life simulations for students. Blake Farmer/WPLN hide caption