Researchers at Science Applications International Corporation in San Diego have been studying the sun’s corona and its impact on space weather for well over a decade. Advances in their understanding of the physics of solar activity, made possible by the use of supercomputers at the nearby NSF-funded San Diego Supercomputer Center, have allowed them to move from one-dimensional models of solar flares and coronal mass ejections to 3-D models that can more accurately predict the impact of these phenomena on weather in space. Space weather can have a major impact on Earth’s power grids, communications, satellites and other essential systems.