US postage stamps honor scientists
New U.S. postage stamps are giving science fans a chance to send letters and recall pioneering researchers at the same time.
The four-stamp set of forever stamps sell at the current first-class rate of 44-cents each. They went on sale nationwide Thursday.
Honored on the stamps are pioneering botanist Asa Gray and three Nobel prize winners, chemist Melvin Calvin; physicist Maria Goeppert Mayer and biochemist Severo Ochoa.