When the solar cycle was at a minimum level in 1996, the Sun sprayed Earth with relatively few, weak high-speed streams containing turbulent magnetic fields (left). In contrast, the Sun bombarded Earth with stronger and longer-lasting streams last year (right) even though the solar cycle was again at a minimum level. The streams affected Earth's outer radiation belt, posing a threat to earth-orbiting satellites, and triggered space weather disturbances, lighting up auroras in the sky at higher latitudes.
Illustration by Janet Kozyra using images from NASA, courtesy Journal of Geophysical Research – Space Physics