Solar Magnetic Eruptions (SME) may cause the ejection of magnetized gas into interplanetary space. These eruptions, known as Coronal Mass Ejections (CMEs), may generate interplanetary transient disturbances involving shocks and magnetic clouds. If these disturbances encounter the Earth’s magnetic field they can cause geomagnetic storms (observed as polar auroras). In severe cases these storms can damage technological systems like satellites, communications and navigation systems, power lines, as well as pose danger to astronauts. Although CMEs are quite frequent (one or two a day during periods of solar maximum activity), only fraction of them hit the Earth's magnetosphere and cause geomagnetic storms. Severe storms occur with a frequency of about 100 times over the 11-year cycle of solar activity. Extremely severe storms occur about 4 times during this period. As humans depend more and more on advanced technological systems, and as they expand into the space environment, the knowledge of "space weather" becomes more important. Numerical modeling represents an important tool for understanding and eventually forecasting space weather. The results of this study were obtained from a numerical simulation using a 3D magneto hydrodynamic (MHD) heliospheric model that describes the solar wind density, temperature, magnetic field components and velocity components. The MHD model is driven by a solar eruption simulated using a coronal model developed by the Science Application International Company (SAIC). The heliospheric computations are carried out on a spherical grid, with the Sun located at the center, ranging from 20 to 270 solar radii. Credit: UCAR