Cosmic ray visual phenomena
Encyclopedia
Cosmic ray visual phenomena, also referred to as phosphenes or "light flashes", are spontaneous flashes of light visually perceived by astronauts outside the magnetosphere
of the Earth, such as during the Apollo program. Researchers believe that cosmic ray
s are responsible for these flashes of light, though the exact mechanism is unknown. Hypotheses include one or all of: Cherenkov radiation
created as the cosmic ray particles pass through the vitreous humor of the astronauts' eye
s, direct interaction with the retina/optic nerve, or direct interaction with visual centres in the brain.
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 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.
More recently, the SilEye/Alteino and ALTEA projects have investigated the phenomenon aboard the International Space Station
, using helmets similar in nature to those in the ALFMED experiment.
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...
of the Earth, such as during the Apollo program. Researchers believe that cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...
s are responsible for these flashes of light, though the exact mechanism is unknown. Hypotheses include one or all of: Cherenkov radiation
Cherenkov radiation
Cherenkov radiation is electromagnetic radiation emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium...
created as the cosmic ray particles pass through the vitreous humor of the astronauts' eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
s, direct interaction with the retina/optic nerve, or direct interaction with visual centres in the brain.
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 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
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
than during the return transit to Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
.
During the Apollo 16
Apollo 16
Young and Duke served as the backup crew for Apollo 13; Mattingly was slated to be the Apollo 13 command module pilot until being pulled from the mission due to his exposure to rubella through Duke.-Backup crew:...
and Apollo 17
Apollo 17
Apollo 17 was the eleventh and final manned mission in the American Apollo space program. Launched at 12:33 a.m. EST on December 7, 1972, with a three-member crew consisting of Commander Eugene Cernan, Command Module Pilot Ronald Evans, and Lunar Module Pilot Harrison Schmitt, Apollo 17 remains the...
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.
More recently, the SilEye/Alteino and ALTEA projects have investigated the phenomenon aboard the International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...
, using helmets similar in nature to those in the ALFMED experiment.