The Sun may appear to be a bright, steadily shining orb, but it is actually a seething cauldron of hot gases prone to violent eruptions. The most dramatic eruptions are coronal mass ejections (CMEs), in which giant, bubble-shaped balloons of plasma and magnetic field lines blast outward at speeds of up to 1,500 miles per second. CMEs can eject up to 200 billion pounds of matter into interplanetary space. These bursts of plasma can wreak havoc if they impact the Earth. CMEs have the potential to disable satellites, disrupt pager and cell phone networks, and knock out electrical power grids. They also pose a danger to astronauts, particularly future travelers to Mars. Solar physicists Jun Lin (Harvard-Smithsonian Center for Astrophysics) and Terry G. Forbes (University of New Hampshire) have developed a state-of-the-art computer model for the massive solar eruptions. “An astronaut on Mars, unprotected by a strong magnetic field and thick atmosphere like we have on Earth, could be exposed to a lethal dose of radiation and ionized particles. All of these reasons show why it is so important that we understand, and eventually be able to predict, CMEs,” said Lin.