When describing distances in the solar system, it can be cumbersome to use common units of length, such as kilometers or miles. Instead, scientists use astronomical units to make the numbers more manageable. Watch this video description...

NASA's New Horizons spacecraft is only a year away from Pluto. Researchers are buzzing with anticipation as NASA prepares to encounter a new world for the first time in decades. (July 14, 2014) [3:22]