Cosmic ray visual phenomena 1364633 206152153 2008-04-17T01:38:42Z 152.23.99.35 Astronauts outside the magnetosphere of the Earth (such as during the [[Apollo program]]) perceived a visual phenomenon in which they saw spontaneous flashes of light. It is believed that [[cosmic ray]]s were responsible for these flashes of light, which were the result of [[Cerenkov radiation]] created as the cosmic ray particles passed through the [[vitreous humor]] of the astronauts' [[eye]]s. Astronauts almost always reported that the flashes were white, with one exception in which the astronaut observed "blue with a white cast, like a blue diamond". There were a few different types of flashes: "spots" and "stars" were observed 66% of the time, "streaks" were observed 25% of the time, and "clouds" were observed 8% of the time. Once their eyes became [[Dark adaptation|adapted to the dark]], Apollo astronauts reported seeing this phenomenon once every 2.9 minutes on average. They also reported that they observed the phenomenon more frequently during the transit to the [[Moon]] than during the return transit to [[Earth]]. During the [[Apollo 16]] and [[Apollo 17]] transits, astronauts conducted the [[ALFMED Experiment]] where an astronaut wore a helmet designed to capture the tracks of cosmic ray particles to determine if they coincided with the visual observation. Examination of the results showed that two of fifteen tracks coincided with observation of the flashes. These results in combination with considerations for geometry and Monte Carlo estimations led researchers to conclude that the visual phenomenon were indeed caused by cosmic rays. == See also == * [[Microwave auditory effect]] == References == * [http://lsda.jsc.nasa.gov/books/apollo/S4CH2.htm Biomedical Results of Apollo - Apollo Light Flash Investigations (sec.4,ch.2)] [[Category:Vision]] [[Category:Cosmic rays]] [[Category:Radiation health effects]] [[Category:Apollo program]] {{astronomy-stub}}