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Aligned, Multiple-transient Events in the First Palomar Sky Survey

"Aligned, Multiple-transient Events in the First Palomar Sky Survey" and "Transients in the Palomar Observatory Sky Survey (POSS-I) may be associated with nuclear testing and reports of unidentified anomalous phenomena" are the names of two companion papers published in October 2025 in Publications of the Astronomical Society of the Pacific and Scientific Reports, respectively. The principal authors of the two papers were astronomer Beatriz Villarroel and clinical psychologist Stephen Bruehl.

Aligned, Multiple-transient Events in the First Palomar Sky Survey
AuthorBeatriz Villarroel and Stephen Bruehl
LanguageEnglish
PublishedPublications of the Astronomical Society of the Pacific
Publication date
October 2025
TextAligned, Multiple-transient Events in the First Palomar Sky Survey online
Transients in the Palomar Observatory Sky Survey (POSS-I) may be associated with nuclear testing and reports of unidentified anomalous phenomena
AuthorBeatriz Villarroel and Stephen Bruehl
LanguageEnglish
PublishedScientific Reports
Publication date
October 2025
TextTransients in the Palomar Observatory Sky Survey (POSS-I) may be associated with nuclear testing and reports of unidentified anomalous phenomena online

The authors of the two papers contended that their research indicated the potential presence of UFOs orbiting the Earth in the 1950s. Their conclusions or research methodology were met with wide skepticism, and criticized by physicists including Michael Wiescher, Nigel Hambly, Kevin Knuth, and others.

Background

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In the 1950s, San Diego's Mount Palomar Observatory photographed the northern sky in small sections. Subsequent research observed that some features present in the Palomar survey did not appear in later surveys. The difference was generally attributed to faults in the Palomar Observatory's glass photographic plates.[1] In a 2021 paper, Beatriz Villarroel and several co-authors concluded the plate fault explanation for the Palomar artifacts was unlikely.[1] The paper's conclusion was rejected in a rejoinder paper by University of Edinburgh astronomers.[1]

Content

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"Transients in the Palomar Observatory Sky Survey (POSS-I) may be associated with nuclear testing and reports of unidentified anomalous phenomena", published in Scientific Reports, and its companion paper, "Aligned, Multiple-transient Events in the First Palomar Sky Survey", published in Publications of the Astronomical Society of the Pacific, studied digital scans of the original Palomar photographic glass plates and determined that the frequency of the transients increased around the time of nuclear tests and civilian UFO sightings.[1][2][3][4][5] In "Transients in the Palomar Observatory Sky Survey", the authors present arguments against several "prosaic explanations", such as plate defects, and advance two hypotheses to explain their findings: that of a "previously undocumented atmospheric phenomenon triggered by nuclear detonations" or that "nuclear weapons may attract UAP [UFOs]".[6] Of the two, the authors claim the first hypothesis is unlikely.[6]

Both papers were published in October 2025.[1][7][8]

Authors

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"Transients in the Palomar Observatory Sky Survey" was authored by Villarroel, an astronomer at the Nordic Institute for Theoretical Physics and by Stephen Bruehl, a psychologist at Vanderbilt University, with Bruehl serving as corresponding author.[6][9][2] "Aligned, Multiple-transient Events in the First Palomar Sky Survey" was authored by Villarroel and Bruehl, with Villarroel serving as corresponding author. They were joined by Enrique Solano, Hichem Guergouri, Alina Streblyanska, Vitaly M. Andruk, Lars Mattsson, Rudolf E. Bär, Jamal Mimouni, Stefan Geier, Alok C. Gupta, Vanessa Okororie, Khaoula Laggoune, Matthew E. Shultz, and Robert A. Freitas Jr.[10][11]

Reception

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The two papers, principally authored by Beatriz Villarroel and Stephen Bruehl, were based on scans of images created by the Mount Palomar Observatory (pictured) in the 1950s.

The two papers were critically received by the scientific community and met with wide skepticism.[12]

Rejection of preprints by arXiv

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ArXiv declined to archive preprints of either paper, asserting they lacked "sufficient or substantive scholarly research".[13][14] Villaroel reacted to this decision on Twitter, writing "Empirical results, peer review, and publication in high-quality journals are no longer enough to satisfy the gatekeepers".[15]

Initial skepticism by scientists

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The papers were met with wide skepticism.[12]

Scientific American noted that there were many simpler explanations, and that this provided an opportunity for UFO skeptics and enthusiasts to see how extraordinary claims are scientifically tested.[13] Michael C. F. Wiescher suggested Villarroel, Bruehl, and their coauthors had actually been observing debris that resulted from earlier nuclear tests and that would give the appearances of "bursts of radiance" when seen through a telescope.[13] SETI's Eliot Gillum noted that Villarroel's results could be explained by meteors that flew directly towards the telescope's view, instead of perpendicular to it, resulting in the appearance of specks of light as opposed to streaks.[13] Sean M. Kirkpatrick stated the results were probably the result of either solar flare radiation or high-altitude balloons.[13]

Princeton University's Robert Lupton, a research astronomer, commented he was left unimpressed with the strength of the statistical analysis undertaken in Villarroel and Bruehl's research.[16] Nigel Hambly, who specializes in digitized optical sky surveys,[16] suggested that examining the actual plates—instead of digital copies as Villarroel and Bruehl did—might result in a different conclusion, and that "there's no shame in being wrong".[13] Writing on his personal website, Adam Frank applauded the researchers' effort at peer review of the two papers, though cautioned that "getting your paper published in a peer-reviewed quality journal does not make it right".[17]

Other critics noted that the 1950s were a "golden age" of UFO sightings and the results correlating the appearance of the artifacts with UFO reports could be attributed to observation bias.[18] The Center for UFO Studies maintains a historic database of UFO sightings (UFOCAT) which was used by Villarroel and Bruehl.[6]

Knuth, et al. rejoinder

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In a preprint of a rejoinder paper, Kevin Knuth; Wesley Andres Watters, a physicist at Wellesley College; and Laura Dominé, a physicist at Japan's National Institute of Information and Communications Technology, rejected the conclusions of the Villarroeal et al. papers, noting what they identified as several issues, including that "even tentative identification of optical flashes required close microscopic analysis, which B. Villarroel et al. did not perform", that the paper contained "inconsistent statements concerning data preparation", that the papers used "circular reasoning and tautological claims" to draw their conclusions, and that the papers employed datasets that had "not been validated in ways that are necessary for their use in a scientific study".[19]

Independent analysis by Busko

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In a preprint, Ivo Busko, a now-retired developer at NASA, reported findings of an independent analysis of archival plates taken at another observatory, the Hamburg Observatory with the Großer Schmidtspiegel 1.2-m Schmidt camera, also from the mid-1950s. Its preliminary results indicate potential evidence of transients similar to those previously reported by the POSS plates study.[20][21]

References

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  1. 1 2 3 4 5 Starr, Michelle (October 29, 2025). "Study Links Mysterious Lights in The Sky to Historic Nuclear Tests". Science Alert. Retrieved October 29, 2025.
  2. 1 2 Cooper, Keith (2025-10-29). "Could these mysterious flashes of light in 1950s photos be UFOs? Some researchers think so". Space. Retrieved 2025-11-09.
  3. ↑ Arnold, Paul (2025-10-27). "Mysterious transient objects in sky linked to nuclear testing and unidentified anomalous phenomena". phys.org. Retrieved 2025-11-09.
  4. ↑ Anderson, Paul Scott (2025-10-29). "Transient flashes in '50s sky plates still puzzle scientists". EarthSky. Retrieved 2025-11-09.
  5. ↑ Bergenholtz-Foglander, Johnny. "Unexpected patterns in historical astronomical observations - Stockholm University". www.su.se. Retrieved 2025-11-09.
  6. 1 2 3 4 Bruehl, Stephen (October 20, 2025). "Transients in the Palomar Observatory Sky Survey (POSS-I) may be associated with nuclear testing and reports of unidentified anomalous phenomena". Scientific Reports. 15 (34125) 34125. Bibcode:2025NatSR..1534125B. doi:10.1038/s41598-025-21620-3. PMC 12537931. PMID 41115916.
  7. ↑ Lagatta, Eric (October 28, 2025). "Did aliens spy on our nuclear tests? Study finds signs of UFOs near US sites in 1950s". USA Today. Retrieved November 6, 2025.
  8. ↑ Evers, Marco (October 26, 2025). "Vieles von dem, was wir Weltraumschrott nennen, ist nicht von uns". Der Spiegel (in German). Retrieved November 6, 2025.
  9. ↑ "Stephen Bruehl, Ph.D." Pain Research Group. Vanderbilt University. Retrieved November 3, 2025.
  10. ↑ Villarroel, Beatriz (October 17, 2025). "Aligned, Multiple-transient Events in the First Palomar Sky Survey". Publications of the Astronomical Society of the Pacific. 137 (10). Bibcode:2025PASP..137j4504V. doi:10.1088/1538-3873/ae0afe. hdl:10261/407641.
  11. ↑ Mendenhall, Brooks (October 31, 2025). "Did aliens watch 1950s nuclear tests? 'Maybe,' studies say". Astronomy. Retrieved November 6, 2025.
  12. 1 2 Billings, Lee (February 20, 2026). "Trump's order to release evidence for aliens obscures the scientific search for extraterrestrial life". Scientific American. Retrieved February 24, 2026. Beyond the federal realm, some space scientists such as Avi Loeb, an astrophysicist at Harvard University, and Beatriz Villarroel, a researcher at the Nordic Institute for Theoretical Physics in Sweden, have independently presented claims of evidence for possible alien visitation... These claims have been widely met with skepticism by other scientists, with some arguing that these observations can be explained by natural causes or human activity.
  13. 1 2 3 4 5 6 O'Callaghan, Jonathan (October 28, 2025). "UFOs Are Just One Explanation for Mysterious Patterns in Old Telescope Data". Scientific American. Retrieved October 29, 2025.
  14. ↑ Ramskov, Jens (November 3, 2025). "Mystiske mønstre fundet i astronomers observationer: Skyldes de atombomber og UFO'er?". Ingeniøren (in Danish). Retrieved November 3, 2025.
  15. ↑ "DrBeaVillarroel on Twitter". Retrieved 3 February 2026.
  16. 1 2 Howell, Elizabeth (November 21, 2025). "A Mysterious UFO Sighting Went Unsolved for 70 Years—Now 'Rigorous' Tests May Confirm It, Scientists Say". Popular Mechanics. Retrieved November 22, 2025.
  17. ↑ Frank, Adam. "Did Science Just Confirm 1950s UFO Visits?". Everyman's Universe. Adam Frank. Retrieved November 2, 2025.
  18. ↑ Öztürk, Levent (November 1, 2025). "1950'lerin sırrı çözülüyor: Fotoğraf plakalarındaki gizemli ışıklar UFO mu?". CHIP Online (in Turkish). Retrieved November 1, 2025.
  19. ↑ Watters, Wesley Andrés (2026). "Critical Evaluation of Studies Alleging Evidence for Technosignatures in the POSS1-E Photographic Plates". arXiv:2601.21946 [astro-ph.IM].
  20. ↑ Ivo Busko (2026). "Searching for Fast Astronomical Transients in Archival Photographic Plates". arXiv:2603.20407 [astro-ph.IM].
  21. ↑ Jarman, Sam. "Unexplained sky flashes from the 1950s: Independent analysis supports their existence". phys.org. Retrieved 2 April 2026.

Further reading

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