The Sun goes through phases of strong activity, during which eruptions can occur. Such eruptions can have multiple components, including X rays, coronal mass ejection plasma, and solar energetic particles – bursts or events of fast-moving particles. These events can occur suddenly and have the potential to rapidly change the radiation environment of wide swaths of the inner solar system where they may create hazardous conditions.
Not only are such conditions dangerous for humans in space, but the intense ionizing radiation can also affect the interior of spacecraft, including sensitive electronics.
Solar energetic particles can reach all regions of near-Earth space, including the lunar surface, with the exception of low-altitude and low-latitude Earth orbit, where the Earth’s magnetic field is strong enough to form a protective barrier.
An intense solar eruptive event has many parts. This animation starts with a solar flare, which sends light and energy in straight paths, traveling at the speed of light. A coronal mass ejection, or CME, appears next – this is a giant cloud of solar particles that also expands in a straight direction with speeds up to two thousand miles an hour. The eruption also generates solar energetic particles, with speeds nearly reaching the speed of light, following the spiral shape of the solar wind’s magnetic fields into interplanetary space.
A close up of a solar eruptive event, including a solar flare, a coronal mass ejection (or CME), and a solar energetic particle event. Several of the processes leading to the CME and solar particle event are not yet understood.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 220.127.116.11.0