Within Apollo 11 Sightings
Why Did Apollo 11 Astronauts See Flashes?
Buzz Aldrin's cabin flashes became important evidence for how cosmic particles can affect human vision in space.
On this page
- Aldrin's report of flashes in the darkened cabin
- How particle interactions became the leading explanation
- Why the flashes are not the same as the UFO sighting
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Introduction
One of the lesser-known Apollo 11 observations had nothing to do with unidentified spacecraft outside the window. Instead, it happened inside the darkened cabin. Buzz Aldrin reported seeing brief flashes of light while trying to sleep during the journey to the Moon, even though no obvious external source was visible. Similar reports later came from other Apollo crews. What began as a puzzling sensory experience eventually became an important clue about how deep-space radiation affects the human body. [PMC]pmc.ncbi.nlm.nih.govPMCLight flashes and other sensory illusions perceived in space…by L Narici · 2023 · Cited by 9 — The first reported observation of th… [NASA]nasa.govNASA'Seeing' Cosmic Rays in Space19 Apr 2012 — Neil Armstrong and Buzz Aldrin both reported these flashes during the Apollo 11 mission, a…
These “light flashes” became scientifically significant because they offered direct evidence that high-energy particles from space could interact with the visual system. Over time, researchers concluded that the flashes were most likely caused by cosmic rays or other energetic charged particles passing through the astronauts’ eyes or nervous system. The phenomenon is now considered distinct from the more famous Apollo 11 “UFO” discussion involving an object seen outside the spacecraft. PMC [2lsda.jsc.nasa.gov]lsda.jsc.nasa.govApollo Light Flash InvestigationsA second explanation was that the bulk of the reported light flashes were caused by cosmic ray particles…
Why Did Apollo 11 Astronauts See Flashes?
Aldrin’s report inside the darkened cabin
During the post-mission technical debriefing, Buzz Aldrin described intermittent flashes appearing while the cabin lights were out and the crew were attempting to sleep. The flashes were not linked to visible external objects and seemed to occur internally, within the astronauts’ field of vision. PMC [New York Post]nypost.comAldrin, the second man to walk on the moon, reported three specific anomalies: an object observed near the spacecraft, initially suspecte…
The reports attracted attention because astronauts were highly trained observers accustomed to unusual visual conditions. Aldrin did not describe the flashes as alien craft or structured objects. Instead, he described brief points or streaks of light that appeared unexpectedly in darkness. Later Apollo crews described comparable experiences, sometimes even with their eyes closed. [PMC]pmc.ncbi.nlm.nih.govPMCLight flashes and other sensory illusions perceived in space…by L Narici · 2023 · Cited by 9 — The first reported observation of th… [Wikipedia]WikipediaCosmic ray visual phenomenaCosmic ray visual phenomena
This mattered because the observations suggested the source was not ordinary reflected sunlight entering the cabin. If astronauts could still perceive flashes with closed eyes, the cause had to involve the visual system itself.
What the flashes looked like
Across Apollo, Skylab, Mir and later space missions, astronauts described several recurring patterns:
- Brief white flashes
- Streaks crossing the visual field
- Spark-like bursts
- Tiny star-shaped points
- Occasional branching or segmented lines
Researchers later grouped these experiences under the label “cosmic ray visual phenomena” or “astronaut’s eye”. Apollo astronauts most commonly reported white flashes, particularly during lunar missions outside Earth’s magnetic protection. [Wikipedia]WikipediaApolloAs the patron deity of Delphi (Apollo Pythios), Apollo is an oracular god—the prophetic deity of the Delphic Oracle and the deit… [ScienceDirect]sciencedirect.comPositive visual phenomena in space: A scientific case and…by WG Sannita · 2006 · Cited by 64 — Most astronauts on Apollo, Skylab, and…
The flashes were often easiest to notice in darkness before sleep, when the eyes had adapted to low light conditions. That matched Aldrin’s original Apollo 11 description. [Wikipedia]WikipediaApollo 11Apollo 11Apollo 11 (July 16–24, 1969) was the American spaceflight that first landed humans on the Moon, and the fifth crewed mission…
How Space Radiation Became the Leading Explanation
Cosmic rays and the human visual system
The leading explanation emerged from space medicine and radiation physics rather than UFO investigation. Scientists concluded that energetic particles travelling through space could directly stimulate parts of the eye or nervous system. PMC [2lsda.jsc.nasa.gov]lsda.jsc.nasa.govApollo Light Flash InvestigationsA second explanation was that the bulk of the reported light flashes were caused by cosmic ray particles…
Deep space contains galactic cosmic rays: extremely energetic atomic particles originating outside the Solar System. Earth’s atmosphere and magnetic field shield people from most of them on the ground, but Apollo astronauts travelling to the Moon spent days outside much of that protection. [NASA]lsda.jsc.nasa.govApollo Light Flash InvestigationsA second explanation was that the bulk of the reported light flashes were caused by cosmic ray particles…
Researchers proposed several related mechanisms:
- A charged particle passing through the retina could trigger rods and cones directly.
- Radiation could stimulate neurons somewhere along the visual pathway.
- Some flashes might involve Cherenkov radiation, faint light produced when particles move through eye fluids faster than light travels in that medium. [Universe Today]universetoday.comseeing cosmic rays in spaceSeeing' Cosmic Rays in Space19 Apr 2012 — When a cosmic ray happens to pass through the retina it causes the rods and cones to fire, and…
In practical terms, the astronauts were sometimes “seeing” radiation itself.
The experiments that strengthened the case
Apollo missions after Apollo 11 attempted to study the phenomenon scientifically. Apollo 16 and Apollo 17 carried the Apollo Light Flash Moving Emulsion Detector experiment, usually shortened to ALFMED. [Wikipedia]WikipediaCosmic ray visual phenomenaCosmic ray visual phenomena
The idea was straightforward: if cosmic particles were causing the flashes, detectors should record particle tracks near the same time astronauts reported seeing them. According to NASA summaries, some correlations were found between observed flashes and detected particle tracks, supporting the radiation explanation. [Wikipedia]WikipediaApolloAs the patron deity of Delphi (Apollo Pythios), Apollo is an oracular god—the prophetic deity of the Delphic Oracle and the deit…
Later International Space Station experiments, including ALTEA and SilEye, continued studying the effect decades after Apollo. These projects again found links between high-energy particles and visual phenomena experienced by astronauts. [Wikipedia]WikipediaApollo 11Apollo 11Apollo 11 (July 16–24, 1969) was the American spaceflight that first landed humans on the Moon, and the fifth crewed mission… [ScienceDirect]sciencedirect.comScienceDirectLight flashes and other sensory illusions perceived in…by L Narici · 2024 · Cited by 9 — While the light flashes appear n…
The evidence did not settle every detail of the mechanism, but it strongly shifted the discussion away from external objects and towards neuro-radiological effects.
Why These Flashes Were Different From the Apollo 11 UFO Sighting
Internal sensation versus external observation
The distinction between the two Apollo 11 phenomena is crucial. The better-known “UFO” discussion involved a visible object outside the spacecraft during translunar flight. The crew used a monocular to observe it and discussed whether it might be part of the Saturn V hardware or other debris. [NASA]nasa.govalsj and afjNASAThe Apollo Lunar Surface Journal and Apollo Flight Journal19 Dec 2025 — The Apollo Lunar Surface Journal and Apollo Flight Journal ar…
The light flashes were fundamentally different: [sciencedirect.com]sciencedirect.comPositive visual phenomena in space: A scientific case and…by WG Sannita · 2006 · Cited by 64 — Most astronauts on Apollo, Skylab, and…
Apollo 11 object sightingApollo 11 light flashesSeen outside the spacecraftSeen inside the astronauts’ visionObserved visually through windowsOften perceived in darkness or with eyes closedDiscussed as a possible physical objectTreated as a sensory phenomenonCould have involved nearby mission debrisLinked to cosmic radiation exposure
Because the two experiences are frequently merged in UFO discussions, later retellings sometimes imply the flashes were evidence of external craft surrounding Apollo 11. The documentary record does not support that interpretation. Aldrin’s flashes were reported separately and eventually became part of biomedical research into spaceflight radiation. PMC [2lsda.jsc.nasa.gov]lsda.jsc.nasa.govApollo Light Flash InvestigationsA second explanation was that the bulk of the reported light flashes were caused by cosmic ray particles…
Why the misunderstanding persists
Several factors helped blur the distinction over time:
- Both events occurred on the same historic mission.
- Early descriptions used terms like “flashes” and “lights”.
- Public UFO culture often grouped all unexplained astronaut observations together.
- Some later media treatments omitted the radiation explanation entirely. [New York Post]nypost.comAldrin, the second man to walk on the moon, reported three specific anomalies: an object observed near the spacecraft, initially suspecte… [The Sun]thesun.co.ukThe Sun Apollo mission pics in UFO files show orbs over the moongovernment reveal that Apollo 17 astronauts observed mysterious lights and objects during their December 1972 mission to the Moon. The do…
The confusion increased whenever newly released archives or debriefings resurfaced online without technical context. In many retellings, ordinary scientific uncertainty was reframed as hidden evidence of extraterrestrial encounters.
Why the Light Flash Discovery Still Matters
A space medicine problem, not just an Apollo curiosity
The flashes turned out to have long-term importance beyond Apollo folklore. They became an early warning that human nervous systems react directly to deep-space radiation exposure. [ScienceDirect]sciencedirect.comPositive visual phenomena in space: A scientific case and…by WG Sannita · 2006 · Cited by 64 — Most astronauts on Apollo, Skylab, and…
For short lunar missions, NASA concluded the flashes themselves were not dangerous. However, the underlying radiation environment remained a major concern. Galactic cosmic rays and solar energetic particles can damage tissue, increase cancer risk, and potentially affect cognition during long-duration missions. [Science News]sciencenews.orgScience News50 years ago, cosmic rays may have caused ApolloMay 12, 2023 — The light flashes and streaks seen by Apollo astronauts have long been attributed to high-energy, heavy cosmic particles (…
That issue has become more important again during the Artemis era, because crews travelling beyond low Earth orbit will once more encounter the same deep-space radiation environment experienced by Apollo astronauts. [Space]space.comHere's why scientists are excitedMay 8, 2026 — In April 2026, during NASA's Artemis 2 mission—the first crewed lunar flight since 1972—th…
Apollo 11’s unexpected contribution to radiation science
In hindsight, Aldrin’s report helped open a new research field linking spaceflight, radiation biology and human perception. What initially sounded like a strange anecdote became valuable evidence that astronauts were physically sensing the high-energy particle environment around them. PMC [2lsda.jsc.nasa.gov]lsda.jsc.nasa.govApollo Light Flash InvestigationsA second explanation was that the bulk of the reported light flashes were caused by cosmic ray particles…
That is why the Apollo 11 light flashes remain scientifically important even though they are much less famous than the mission’s debated external sighting. The flashes were never strong evidence for a UFO encounter. Instead, they became one of the earliest human observations of how deep space itself can intrude directly into perception.
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Endnotes
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC10919968/Source snippet
PMCLight flashes and other sensory illusions perceived in space...by L Narici · 2023 · Cited by 9 — The first reported observation of th...
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Source: nasa.gov
Link: https://www.nasa.gov/wp-content/uploads/2021/11/seeingcosmicraysinspace.pdfSource snippet
NASA'Seeing' Cosmic Rays in Space19 Apr 2012 — Neil Armstrong and Buzz Aldrin both reported these flashes during the Apollo 11 mission, a...
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Source: sciencedirect.com
Link: https://www.sciencedirect.com/science/article/pii/S0042698905006735Source snippet
Positive visual phenomena in space: A scientific case and...by WG Sannita · 2006 · Cited by 64 — Most astronauts on Apollo, Skylab, and...
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Source: lsda.jsc.nasa.gov
Link: https://lsda.jsc.nasa.gov/Experiment/exper/380Source snippet
Apollo Light Flash InvestigationsA second explanation was that the bulk of the reported light flashes were caused by cosmic ray particles...
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Source: Wikipedia
Title: Cosmic ray visual phenomena
Link: https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena -
Source: sciencedirect.com
Link: https://www.sciencedirect.com/science/article/pii/S0939388923000818Source snippet
ScienceDirectLight flashes and other sensory illusions perceived in...by L Narici · 2024 · Cited by 9 — While the light flashes appear n...
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Source: nasa.gov
Title: alsj and afj
Link: https://www.nasa.gov/history/alsj-and-afj/Source snippet
NASAThe Apollo Lunar Surface Journal and Apollo Flight Journal19 Dec 2025 — The Apollo Lunar Surface Journal and Apollo Flight Journal ar...
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Source: space.com
Link: https://www.space.com/space-exploration/artemis/nasas-artemis-2-astronauts-saw-flashes-on-the-far-side-of-the-moon-that-cameras-struggle-to-capture-heres-why-scientists-are-excitedSource snippet
Here's why scientists are excitedMay 8, 2026 — In April 2026, during NASA's Artemis 2 mission—the first crewed lunar flight since 1972—th...
Published: May 8, 2026
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Source: nasa.gov
Link: https://www.nasa.gov/the-apollo-program/Source snippet
The Apollo ProgramProject Apollo's goals went beyond landing Americans on the moon and returning them safely to Earth. The national effor...
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Source: Wikipedia
Link: https://en.wikipedia.org/wiki/ApolloSource snippet
ApolloAs the patron deity of Delphi (Apollo Pythios), Apollo is an oracular god—the prophetic deity of the Delphic Oracle and the deit...
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Source: Wikipedia
Title: Apollo 11
Link: https://en.wikipedia.org/wiki/Apollo_11Source snippet
Apollo 11Apollo 11 (July 16–24, 1969) was the American spaceflight that first landed humans on the Moon, and the fifth crewed mission...
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Source: avi-loeb.medium.com
Title: we should not mistake cosmic rays for ufos 8d10b0085b9c
Link: https://avi-loeb.medium.com/we-should-not-mistake-cosmic-rays-for-ufos-8d10b0085b9cSource snippet
Should Not Mistake Cosmic-Rays for UFOs! | by Avi LoebThe astronauts noticed 6 flashes of light which are likely the result of impacts of...
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Source: nypost.com
Link: https://nypost.com/2026/05/08/us-news/buzz-aldrin-described-unusual-phenomena-during-apollo-11-mission-ufo-docs-reveal/Source snippet
Aldrin, the second man to walk on the moon, reported three specific anomalies: an object observed near the spacecraft, initially suspecte...
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Source: nypost.com
Link: https://nypost.com/2026/05/22/us-news/apollo-12-crew-describes-mysterious-streaks-of-light-in-declassified-ufo-files/ -
Source: livescience.com
Title: Live Science Astronauts can face ‘nearly lethal doses’ of solar radiation
Link: https://www.livescience.com/space/space-exploration/astronauts-can-face-nearly-lethal-doses-of-solar-radiation-so-why-launch-artemis-ii-during-the-suns-peak-of-activity-space-scientist-patricia-reiff-explainsSource snippet
Space scientist Patricia Reiff explains.NASA’s Artemis II mission—a crewed flight around the Moon—coincides with a period of heightened s...
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Source: universetoday.com
Title: seeing cosmic rays in space
Link: https://www.universetoday.com/articles/seeing-cosmic-rays-in-spaceSource snippet
'Seeing' Cosmic Rays in Space19 Apr 2012 — When a cosmic ray happens to pass through the retina it causes the rods and cones to fire, and...
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Source: thesun.co.uk
Title: The Sun Apollo mission pics in UFO files show orbs over the moon
Link: https://www.thesun.co.uk/news/39053582/apollo-ufo-files-orbs-moon-astronauts-fireworks/Source snippet
government reveal that Apollo 17 astronauts observed mysterious lights and objects during their December 1972 mission to the Moon. The do...
Published: December 1972
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Source: sciencenews.org
Title: Science News50 years ago, cosmic rays may have caused Apollo
Link: https://www.sciencenews.org/article/cosmic-rays-apollo-astronauts-light-flashesSource snippet
May 12, 2023 — The light flashes and streaks seen by Apollo astronauts have long been attributed to high-energy, heavy cosmic particles (...
Published: May 12, 2023
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Source: britannica.com
Title: Apollo Greek mythology
Link: https://www.britannica.com/topic/Apollo-Greek-mythologySource snippet
Apollo | Facts, Symbols, Powers, & Myths1 May 2026 — Apollo, in Greco-Roman mythology, a deity of manifold function and meaning, one of t...
Published: May 2026
Additional References
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Source: lpi.usra.edu
Link: https://www.lpi.usra.edu/lunar/surface/Apollo11_PhotoSciDebriefing.pdfSource snippet
11 photographic and scientific debriefingCan you estimate the largest angle on the lunar surface at which you saw this coronal - zodiacal...
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Source: reddit.com
Link: https://www.reddit.com/r/todayilearned/comments/pfrthk/til_astronauts_have_long_reported_the_experience/Source snippet
TIL astronauts have long reported the experience of seeing...TIL Astronauts often see random flashes of light in space, even through clo...
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Source: reddit.com
Link: https://www.reddit.com/r/UFOs/comments/1t797wg/unknown_light_orbs_swarmed_apollo_11/Source snippet
Unknown light orbs swarmed Apollo 11: r/UFOsThis is experienced by astronauts all the time. It's caused by high-energy cosmic rays inter...
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Source: greekmythology.com
Link: https://www.greekmythology.com/Olympians/Apollo/apollo.htmlSource snippet
☀ Apollo:: Greek God of Music and LightApollo is the Olympian god of light, music and poetry, healing and plagues, prophecy and knowledg...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/372375638_Light_Flashes_and_other_sensory_illusions_perceived_in_space_travel_and_on_ground_including_proton-_and_heavy_ion-therapiesSource snippet
(PDF) Light Flashes and other sensory illusions perceived...24 Mar 2026 — The first reported observation of this phenomenon was in July...
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Source: facebook.com
Title: a 1969 debrief of buzz aldrin stating he saw a sizable object close to the lunar
Link: https://www.facebook.com/theguardian/posts/a-1969-debrief-of-buzz-aldrin-stating-he-saw-a-sizable-object-close-to-the-lunar/1400585945432988/Source snippet
A 1969 debrief of Buzz Aldrin stating he saw a 'sizable'...During the Apollo 11 moon landing in 1969, Neil Armstrong and Buzz Aldrin wer...
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Source: facebook.com
Title: it includes a strange sighting by buzz aldrin of a bright light source during th
Link: https://www.facebook.com/thewestaustralian/posts/it-includes-a-strange-sighting-by-buzz-aldrin-of-a-bright-light-source-during-th/1304534281785772/Source snippet
It includes a strange sighting by Buzz Aldrin of a bright light...In 1969, during Apollo 11 mission, Buzz Aldrin reported the first expe...
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Source: independent.co.uk
Link: https://www.independent.co.uk/news/world/americas/us-politics/ufo-files-sightings-nasa-moon-landing-photos-b2973322.htmlSource snippet
Astronaut Buzz Aldrin, the second person to walk on the moon, described three strange...Read more...
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Source: war.gov
Link: https://www.war.gov/medialink/ufo/release_1/nasa-uap-d4-apollo-11-technical-crew-debriefing-1969.pdfSource snippet
NASA-UAP-D4, Apollo 11 Technical Crew Debriefing, 196911 Mar 1977 — just one flash, I could see double flashes, at points separated by ma...
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Source: x.com
Link: https://x.com/omar_quraishi/status/2052776375699079530Source snippet
to the Moon; two, flashes of light inside the cabin; and three, a...Read more...
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