1 The origins of space weather
The Earth's dipolar magnetic field is exposed to a continuous stream of charged particles from the Sun known as the solar wind (top). This wind compresses the Earth's protective magnetic shielding, the magnetosphere, on the side nearest the Sun and stretches it out on the far side. The magnetosphere is further compressed by coronal mass ejections, which expel expanding U-shaped bubbles of plasma from the surface of the Sun that are threaded by a magnetic field (bottom). The connection of these field lines with those of the Earth and the compression of the magnetosphere (via the solar wind) creates geomagnetic storms. Image: ESA/NASA