Solar wind is initiated from active solar flare regions. Solar flares start with an active-region prominence: cold dense plasma associated with an arcade of looped magnetic field lines. A prominence can be stable for hours or days but sometimes it takes on a violent evolution: as the magnetic field structure slowly evolves, the loop becomes more and more stretched and the prominence starts rising slowly until the configuration becomes highly unstable and reconnection initiates, causing a large, impulsive energy release which will make the prominence erupt more rapidly; as reconnection continues both the erupting prominence and the plasma on the newly formed loops are heated tremendously causing very bright Xray emissions. Some flares are accompanied by coronal mass ejections where plasma piled up in the corona above the rising magnetic loops is ejected by the intense energy bursts associated with reconnecting field lines. The lower-lying prominence which consists of chromospheric material might be ejected as well. Coronal mass ejections (CME) give rise to large disturbances propagating outward in the solar wind. This picture points out that prominences are a basic source of solar wind in which the Earth’s and planet magnetospheres and other non-magnetized planets are continuously immersed. When emitted in a direction which brings it on a collision course with the Earth, a CME will have a profound impact on the outskirts of the terrestrial atmosphere: the magnetosphere and the ionosphere (Bellan, 2004).