Solar Flares

Most of the cosmic radiation that can affect crewmembers and frequent flyers comes from galactic cosmic rays, originating outside our solar system.  The activity of the sun can reduce or increase this flux of particles from space, but the sun itself is a weak source of cosmic radiation.

Only very rarely does a solar flare accelerate particles to energies sufficient to penetrate the Earth's magnetic field defenses and cause the radiation levels to increase by more than a factor of 10. Only 6 such events have occurred in the last 50 years of the 20th century.

• 23 February 1956
• 17 July 1959
• 13 November 1960
• 09 August 1972
• 20 October 1989
• 24 March 1991
• 20 January 2005

While it is not possible to predict solar flares, several observatories, such as the Space Environment Center, can give early warning of an imminent solar storm. If such an event occurs, PCAire will add an estimate of the exposure you received to your dose records.