The level of cosmic rays bombarding our solar system has hit a 50-year high - a "signficant" increase which could impact on future space missions.
The surge in cosmic rays - "subatomic particles, mainly protons but also some heavy nuclei", Space.com explains - was detected by NASA's Advanced Composition Explorer (ACE) spacecraft.
More: http://www.theregister.co.uk/2009/10/01/cosmic_ray_high/