Karin Bruwelheide handles an amputates limb that dates back to the Civil War. The bones were discovered by scientists at Manassas National Battlefield Park in Virginia. Scientists at the Smithsonian Institution's National Museum of Natural History have been analyzing the bones to learn more about them and who they may have belonged to. Meredith Rizzo/NPR hide caption
Female manta at Flower Garden Banks National Marine Sanctuary G.P. Schmahl/FGBNMS hide caption
Modern tools of biology could allow someone to recreate a dangerous virus, such as smallpox, from scratch. Dr. Hans Gelderblom/Visuals Unlimited/Getty Images hide caption
Kelly Zimmerman holds her son Jaxton Wright at a parenting session at the Children's Health Center in Reading, Pa. The free program provides resources and social support to new parents in recovery from addiction, or who are otherwise vulnerable. Natalie Piserchio for NPR hide caption
Rice within the octagon in this field is part of an experiment to grow rice under different levels of carbon dioxide. Toshihiro Jasegawa, National Agriculture and Food Research Organization of Japan hide caption
Rates of "summer melt" are highest for students from lower-income backgrounds, especially if their own parents didn't go through the college application process. Hill Street Studios/Getty Images/Blend Images hide caption
The South Korean soccer team poses for a photo prior to the 2018 FIFA World Cup match against Sweden at Nizhny Novgorod Stadium on June 18, 2018 in Nizhny Novgorod, Russia. Clive Mason/Getty Images hide caption
The Air Force currently oversees many of the military's space activities, such as the experimental X-37B spacecraft. Michael Stonecypher/USAF hide caption
Stephanie and Natalie enrolled their older son in sessions at a Brain Balance Achievement Center in the hope that it would help him make friends. Hokyoung Kim for NPR hide caption
Steve Nelson (right), president of the Nebraska Farm Bureau, looks on as Scott Pruitt talks to farmers in Reliance, S.D. Grant Gerlock/Harvest Public Media hide caption
A fire at the Husky Oil Refinery on April 26, in Superior, Wis. The Environmental Protection Agency is planning to rescind regulations that would require refineries and chemical manufacturers to disclose information about emergency plans and the root causes of disasters. Stephen Maturen/Getty Images hide caption
Party's over for a federal study about the health effects of moderate alcohol consumption. WIN-Initiative/Getty Images hide caption
Entering the control room at Three Mile Island Unit 1 is like stepping back in time. Except for a few digital screens and new counters, much of the equipment is original to 1974, when the plant began generating electricity. Jeff Brady/NPR hide caption
Professor Stephen Hawking sits onstage during the "Breakthrough Starshot" announcement at One World Observatory on April 12, 2016 in New York City. Jemal Countess/Getty Images hide caption
"Nostalgia is memory with the pain removed." - Jim Holliday Gpointstudio/Getty Images/Cultura RF hide caption
A serving of salmon contains about 600 IUs of vitamin D, researchers say, and a cup of fortified milk around 100. Cereals and juices are sometimes fortified, too. Check the labels, researchers say, and aim for 600 IUs daily, or 800 if you're older than 70. Dorling Kindersley/Getty Images/Dorling Kindersley hide caption
