Cosmic Rays Flash Lights for ISS Crews

Astronauts aboard the International Space Station report seeing flashes of light with eyes closed caused by high-energy cosmic rays passing through their bodies, either directly ionizing the retina or via Cherenkov radiation. Historical experiments (SilEye/ALTEA) linked particle tracks to the flashes, confirming the phenomenon and highlighting space radiation as a detectable, personal readout of exposure and a major shielding challenge for long-duration missions.