Solar particle event

Solar phenomenon Post-eruptive loops in the wake of a solar flare, image taken by the TRACE satellite (photo by NASA) A solar particle event (SPE), also known as a solar energetic particle event or solar radiation storm, is a solar phenomenon that occurs when particles emitted by the Sun, mostly protons, become accelerated either in the Sun's atmosphere during a solar flare or in interplanetary space by a coronal mass ejection shock. Other nuclei such as helium and HZE ions may also be accelerated. These particles can penetrate the Earth's magnetic field and cause partial ionization of the ionosphere. Energetic protons are a significant radiation hazard to spacecraft and astronauts. Description SPEs occur when charged particles in the Sun's atmosphere are accelerated to extremely high velocities. These charged particles, referred to as solar energetic particles, can escape into interplanetary space, where they follow the interplanetary magnetic field. When solar energetic particles interact with the Earth's magnetosphere, they are guided by the Earth's magnetic field towards the North and South poles where they can penetrate into the upper atmosphere. The U.S. National Oceanic and