Solar particle event

[citation needed] Gradual SPEs are thought to involve the acceleration of particles by shocks driven by coronal mass ejections in the upper corona.

They are associated with type II radio bursts and are characterized by elemental abundances, charge states, and temperatures similar to that of the ambient corona.

Impulsive SPEs are thought to involve the acceleration of particles mostly by processes associated with magnetic reconnection and wave-particle interactions at the locations of solar flares.

Polar cap absorption events and the associated HF radio blackout pose unique problems to commercial and military aviation.

Hence, if polar cap absorption events are ongoing or forecast, commercial airlines are required to redirect their routes such that HF communications remain viable.

[5][6] Extremely intense SPEs capable of producing energetic protons with energies in excess of 200 MeV can increase neutron count rates at ground levels through secondary radiation effects.

[9] Some events produce large amounts of HZE ions, although their contribution to the total radiation is small compared to the level of protons.

These events, discovered by physicist Fusa Miyake, have enabled the dating of a number of past SPEs to specific years.

During years of exposure to energetic proton activity from the Sun, spacecraft can lose a substantial amount of electrical power that may require important instruments to be turned off.

When energetic protons strike the sensitive optical electronics in spacecraft (such as star trackers and other cameras) flashes occur in the images being captured.