Warning Times

Warning Times

. Intense radiation, or photons, generated during solar flares passes right through the interplanetary magnetic field and arrives at the Earth just 8 minutes after being emitted from the Sun. In contrast, solar flares beam energetic charged particles across a narrow trajectory that follows the interplanetary magnetic spiral, and the time for the particles to reach Earth depends on their energy and velocity, taking roughly an hour for a particle energy of about 10 MeV. A coronal mass ejection, or CME, with an average speed of 450 thousand meters per second takes about 4 days to travel from the Sun to Earth’s orbit. The CME can energize particles across a wide swath in interplanetary space. The heliospheric current sheet separates magnetic fields of opposite polarities, or directions, denoted by the arrows on the spiral lines. (Courtesy of Frances Bagenal.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University