The Living With a Star program emphasizes the science necessary to improve our understanding of how and why the sun varies; how Earth and the solar system respond; and how the variability and response affect humanity in space and on Earth. One of the program's key goals is to improve our ability to forecast geomagnetic storms and other forms of stormy "space weather." Such events can interrupt or damage satellite communications systems, trigger surges in power grid systems, and increase radiation hazards to orbiting astronauts and spacecraft.