Cosmic ray visual phenomena: Difference between revisions

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{{Short description|none}}

{{Use dmy dates|date=July 2020}}

'''Cosmic ray visual phenomena''', or '''light flashes''' ('''LF'''), also known as '''Astronaut's Eye''', are spontaneous flashes of [[light]] [[visual perception|visually perceived]] by some [[astronaut]]s outside the [[magnetosphere]] of the Earth, such as during the [[Apollo program]]. While LF may be the result of actual photons of visible light being sensed by the retina,<ref name="Hecht1942">{{cite journal |title=Energy, Quanta, and Vision |journal=Journal of General Physiology |first1=Selig |last1=Hecht |first2=Simon |last2=Shlaer |first3=Maurice Henri |last3=Pirenne |volume=25 |issue=6 |pages=819–840 |date=July 1942 |doi=10.1085/jgp.25.6.819 |pmid=19873316 |pmc=2142545}}</ref> the LF discussed here could also pertain to [[phosphenes]], which are sensations of light produced by the activation of neurons along the visual pathway.<ref name="Dobelle1974">{{cite journal |title=Phosphenes produced by electrical stimulation of human occipital cortex, and their application to the development of a prosthesis for the blind |journal=The Journal of Physiology |first1=W. H. |last1=Dobelle |first2=M. G. |last2=Mladejovsky |volume=243 |issue=2 |pages=553–576 |date=December 1974 |doi=10.1113/jphysiol.1974.sp010766 |pmid=4449074 |pmc=1330721}}</ref>

==Possible causes==

Researchers believe that the LF perceived specifically by astronauts in space are due to [[cosmic ray]]s (high-energy charged particles from beyond the Earth's atmosphere<ref name="Mewaldt1996">{{cite book |chapter-url=http://www.srl.caltech.edu/personnel/dick/cos_encyc.html |chapter=Cosmic Rays |title=MacMillan Encyclopedia of Physics |publisher=Simon & Schuster MacMillan |first=R. A. |last=Mewaldt |editor-first=John S. |editor-last=Rigden |volume=1 |date=1996 |isbn=978-0-02-897359-3 |access-date=27 August 2016 |archive-date=30 August 2009 |archive-url=https://web.archive.org/web/20090830191145/http://www.srl.caltech.edu/personnel/dick/cos_encyc.html |url-status=dead }}</ref>), though the exact mechanism is unknown. Hypotheses include [[Cherenkov radiation]] created as the cosmic ray particles pass through the [[vitreous humour]] of the astronauts' [[human eye|eyes]],<ref>{{cite journal |last1=Okike |first1=O. |date=2020 |title=Automated detection of simultaneous/non-simultaneous Forbush decreases and the associated cosmic ray phenomena |url=https://doi.org/10.1016/j.jastp.2020.105460 |journal=Journal of Atmospheric and Solar-Terrestrial Physics |volume=211 |pages= | doi=10.1016/j.jastp.2020.105460}}</ref><ref name="Narici2004">{{cite journal |url=http://people.roma2.infn.it/~morselli/A94Altea.pdf |title=The ALTEA/ALTEINO projects: studying functional effects of microgravity and cosmic radiation |journal=Advances in Space Research |first1=L. |last1=Narici |first2=F. |last2=Belli |first3=V. |last3=Bidoli |first4=M. |last4=Casolino |first5=M. P. |last5=De Pascale |display-authors=etal |volume=33 |issue=8 |pages=1352–1357 |date=January 2004 |doi=10.1016/j.asr.2003.09.052 |pmid=15803627 |bibcode=2004AdSpR..33.1352N}}</ref><ref name="Tendler Hartford Jermyn LaRochelle 2020 pp. 422–429">{{cite journal | last1=Tendler | first1=Irwin I. | last2=Hartford | first2=Alan | last3=Jermyn | first3=Michael | last4=LaRochelle | first4=Ethan | last5=Cao | first5=Xu | last6=Borza | first6=Victor | last7=Alexander | first7=Daniel | last8=Bruza | first8=Petr | last9=Hoopes | first9=Jack | last10=Moodie | first10=Karen | last11=Marr | first11=Brian P. | last12=Williams | first12=Benjamin B. | last13=Pogue | first13=Brian W. | last14=Gladstone | first14=David J. | last15=Jarvis | first15=Lesley A. | title=Experimentally Observed Cherenkov Light Generation in the Eye During Radiation Therapy | journal=International Journal of Radiation Oncology, Biology, Physics | publisher=Elsevier BV | volume=106 | issue=2 | year=2020 | issn=0360-3016 | doi=10.1016/j.ijrobp.2019.10.031 | pages=422–429| pmid=31669563 | pmc=7161418 }}</ref> direct interaction with the [[optic nerve]],<ref name="Narici2004" /> direct interaction with visual centres in the brain,<ref name="Narici2003">{{cite journal |title=ALTEA: Anomalous long term effects in astronauts. A probe on the influence of cosmic radiation and microgravity on the central nervous system during long flights |journal=Advances in Space Research |first1=L. |last1=Narici |first2=V. |last2=Bidoli |first3=M. |last3=Casolino |first4=M. P. |last4=De Pascale |first5=G. |last5=Furano |first6=A. |last6=Morselli |first7=P. |last7=Picozza |first8=E. |last8=Reali |first9=R. |last9=Sparvoli |first10=S. |last10=Licoccia |first11=P. |last11=Romagnoli |first12=E. |last12=Traversa |first13=W. G. |last13=Sannita |first14=A. |last14=Loizzo |first15=A. |last15=Galper |first16=A. |last16=Khodarovich |first17=M. G. |last17=Korotkov |first18=A. |last18=Popov |first19=N. |last19=Vavilov |first20=S. |last20=Avdeev |first21=V. P. |last21=Salnitskii |first22=O. I. |last22=Shevchenko |first23=V. P. |last23=Petrov |first24=K. A. |last24=Trukhanov |first25=M. |last25=Boezio |first26=W. |last26=Bonvicini |first27=A. |last27=Vacchi |first28=N. |last28=Zampa |first29=R. |last29=Battiston |first30=G. |last30=Mazzenga |first31=M. |last31=Ricci |first32=P. |last32=Spillantini |first33=G. |last33=Castellini |first34=P. |last34=Carlson |first35=C. |last35=Fuglesang |display-authors=5 |volume=31 |issue=1 |pages=141–146 |date=2003 |doi=10.1016/S0273-1177(02)00881-5 |pmid=12577991 |bibcode=2003AdSpR..31..141N|url=https://www.openaccessrepository.it/record/138131 |url-access=subscription }}{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}}</ref> [[retina]]l receptor stimulation,<ref name="Charman1971">{{cite journal |title=Visual Sensations produced by Single Fast Particles |journal=Nature |first1=W. N. |last1=Charman |first2=J. A. |last2=Dennis |first3=G. G. |last3=Fazio |first4=J. V. |last4=Jelley |volume=230 |issue=5295 |pages=522–524 |date=April 1971 |doi=10.1038/230522a0 |bibcode=1971Natur.230..522C |pmid=4927751|s2cid=4214913 }}</ref> and a more general interaction of the retina with radiation.<ref name="Tobias1971">{{cite journal |title=Radiation-induced Light Flashes observed by Human Subjects in Fast Neutron, X-ray and Positive Pion Beams |journal=Nature |first1=C. A. |last1=Tobias |first2=T. F. |last2=Budinger |first3=J. T. |last3=Lyman |volume=230 |issue=5296 |pages=596–598 |date=April 1971 |doi=10.1038/230596a0 |bibcode=1971Natur.230..596T |pmid=4928670|s2cid=4260225 }}</ref>

==Conditions under which the light flashes were reported==

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===Colors===

On Lunar missions, astronauts almost always reported that the flashes were white, with one exception where the astronaut observed "blue with a white cast, like a blue diamond." On other space missions, astronauts reported seeing other colors such as yellow and pale green, though rarely.<ref name="Sannita2006">{{cite journal |title=Positive visual phenomena in space: A scientific case and a safety issue in space travel |journal=Vision Research |first1=Walter G. |last1=Sannita |first2=Livio |last2=Narici |first3=Piergiorgio |last3=Picozza |volume=46 |issue=14 |pages=2159–2165 |date=July 2006 |doi=10.1016/j.visres.2005.12.002 |pmid=16510166|s2cid=18240658 |doi-access=free }}</ref> Others instead reported that the flashes were predominantly yellow, while others reported colors such as orange and red, in addition to the most common colors of white and blue.<ref name="Fuglesand2006" />

===Shapes===

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===ALFMED experiment===

[[File:Apollo 17 ALFMED AS17-162-24080HR-et-078HR.jpg|thumb|320px|Apollo 17 astronaut [[Ronald Evans (astronaut)|Ron Evans]] wearing the ALFMED light-flash detector during the outbound flight from Earth]]

During the [[Apollo 16]] and [[Apollo 17]] transits, astronauts conducted the [[Apollo Light Flash Moving Emulsion Detector]] (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 method|Monte Carlo estimations]] led researchers to conclude that the visual phenomena were indeed caused by cosmic rays.<ref name="ALFMED">{{cite web|url=http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/docs/ApolloCat/Part2/ALFMED.htm |title=Experiment: Light Flashes Experiment Package (Apollo light flash moving emulsion detector) |series=Experiment Operation During Apollo IVA at 0-g |publisher=[[NASA]] |date=2003 |archive-url=https://web.archive.org/web/20140511163326/http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/docs/ApolloCat/Part2/ALFMED.htm |archive-date=11 May 2014 |url-status=dead}}</ref><ref name="Osborne1975">{{cite book |chapter-url=https://history.nasa.gov/SP-368/s4ch2.htm |chapter=Apollo Light Flash Investigations |title=Biomedical Results of Apollo |publisher=NASA |first1=W. Zachary |last1=Osborne |first2=Lawrence S. |last2=Pinsky |first3=J. Vernon |last3=Bailey |editor1-first=Richard S. |editor1-last=Johnston |editor2-first=Lawrence F. |editor2-last=Dietlein |editor3-first=Charles A. |editor3-last=Berry |date=1975 |volume=NASA-SP-368 |id=NASA SP-368}}</ref>

===SilEye-Alteino and ALTEA projects===

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Considering the experiments conducted, at least in some cases the LF observed appear to be caused by activation of neurons along the visual pathway, resulting in phosphenes. However, because the researchers cannot definitively rule out the Cherenkov radiation effects as a probable cause of the LF experienced by astronauts, it seems likely that some LF may be the result of Cherenkov radiation effects in the eye itself, instead. The Cherenkov effect can cause Cherenkov light to be emitted in the vitreous body of the eye and thus allow the person to perceive the LF.<ref name="Fuglesand2006" /> Hence, it appears that the LF perceived by astronauts in space have different causes. Some may be the result of actual light stimulating the retina, while others may be the result of activity that occurs in neurons along the visual pathway, producing phosphenes.

== See also ==

* [[Microwave auditory effect]]

* {{annotated link|Anatoli Bugorski}}

* [[{{annotated link|Microwave auditory effect]]}}

==References==