What differentiates a star from even the largest ... Most of an atom's volume is empty space. What holds atom away from atom is the mutual repulsion between electrons, a force sometimes called ...

Stars should be everywhere in space photos, right? Wrong! Learn why the cosmos often looks empty in images from space agencies and what it reveals about how cameras and human eyes work.

NASA astronauts Butch Wilmore and Suni Williams have been stuck in space for months longer than expected, and will not return ...