In 1920, astronomers Harlow Shapley and Heber Curtis held a Great Debate. Shapley argued that the spiral nebulae were small and in the Milky Way, while Curtis took a more radical position that they ...

NASA’s Goddard Space Flight Center in Greenbelt, Md., wants nothing to do with the microscopic dust particles clinging to your clothing. So before you enter the room, you first must stand in a chamber ...