Palomar Observatory
LocationObservatoryPalomar Observatory
LocationObservatoryPalomar Observatory is Caltech's mountaintop observatory in San Diego County, whose 1949-1958 sky-survey plates underpin the VASCO studies of disputed pre-Sputnik transients.
Palomar Observatory is Caltech's mountaintop observatory in San Diego County, whose 1949-1958 sky-survey plates underpin the VASCO studies of disputed pre-Sputnik transients.
Palomar Observatory is an astronomical research observatory on Palomar Mountain in northern San Diego County, California, at about 1,712 meters (5,617 feet). Caltech owns and operates it, with research partners that include NASA's Jet Propulsion Laboratory and Yale University. Its main instruments are the 200-inch Hale Telescope, the 48-inch Samuel Oschin telescope and a robotic 60-inch telescope; the Oschin now carries the camera of the Zwicky Transient Facility, a modern sky survey.
The observatory dates to 1928, when Caltech secured a $6 million Rockefeller Foundation grant to build the Hale Telescope. The great telescope saw first light on January 26, 1949, and remained the world's largest until 1975. Palomar observations helped establish quasars as distant objects, and its smaller telescopes found Comet Shoemaker-Levy 9 and the dwarf planet Eris. From November 1948 to April 1958, the Oschin telescope also photographed the sky down to about 30 degrees south of the celestial equator for the National Geographic Society–Palomar Observatory Sky Survey, known as POSS-I, producing 937 pairs of red and blue glass plates that served as a reference atlas for decades.
Those plates are the basis of the VASCO project led by astronomer Beatriz Villarroel, which compares digitized POSS-I images with modern surveys and reports star-like flashes seen on one exposure and never again. Villarroel's team argues that some of these transients, recorded before Sputnik launched in 1957, may be sunlight glinting off reflective objects in high Earth orbit. A 2025 Scientific Reports paper led by Stephen Bruehl associated them with nuclear-test dates and UFO reports while disclaiming causation, and 2026 preprints modeled altitudes of roughly 20,000 to 35,000 kilometers and mapped apparent hotspots over the Pacific, the southern Gulf of Mexico and the American Southwest. Astronomers Nigel Hambly and Adam Blair have attributed the best-known 1950 cluster to emulsion flaws, and a critique by Wesley Watters and colleagues argued that the reported shortage of transients in Earth's shadow and the nuclear link disappear once the plates' backgrounds and Palomar's observing schedule are properly modeled.
The dispute has turned a mid-century star atlas into a contested historical record. In 2026 Villarroel and Harvard's Jun Yang examined original plate material for two well-known multiple-transient events, while the work reached wide audiences through NewsNation's Reality Check and The Joe Rogan Experience. Because POSS-I fixed the sky on glass before the first artificial satellite, Palomar's archive is now the test bed for whether those flashes are photographic defects or a record of objects above Earth.
Part 25 of a series reassessing the documentary record behind the 1933 Magenta narrative. TL;DR Historical Palomar plates contain unexplained, star-like marks. Some have been recovered by a separate detection pipeline; that establishes reproducible marks in the scans, while their physical origin remains disputed. The Earth-shadow claim has several reported significances under different comparisons. The original paper’s coverage-adjusted result is 7.6σ, rather than its idealized 22σ headline....
On April 12, 1950, a telescope at Palomar Observatory in California photographed a patch of sky on a glass plate. When astronomers re-examined it decades later, they found nine star-like points of light that aren’t on a photo of the same spot taken half an hour earlier and don’t show up in any modern survey. The open challenge is to look at old glass plates from other observatories, using only ones taken before Sputnik. If similar flashes show up there too, it becomes much harder to explain t...
Part 16 of a series reassessing the documentary record behind the 1933 Magenta narrative. TL;DR Historical Palomar plates contain unexplained, star-like marks. Some have been recovered by a separate detection pipeline; that establishes reproducible marks in the scans, while their physical origin remains disputed. The Earth-shadow claim has several reported significances under different comparisons. The original paper’s coverage-adjusted result is 7.6σ, rather than its idealized 22σ headline....
[Retweeted] Project Lost Light invites professional scientists, citizen scientists, and students from around the world to participate in a challenge to replicate -- or challenge -- pre-Sputnik transient studies using historical (pre-Sputnik) photographic plate collections from around the world. First prize: $75,000 Second prize: $50,000 Third prize: $25,000 The competition accepts data from all pre-Sputnik photographic plate collections, except those from Palomar Observatory. Learn how to det...
Project Lost Light invites professional scientists, citizen scientists, and students from around the world to participate in a challenge to replicate -- or challenge -- pre-Sputnik transient studies using historical (pre-Sputnik) photographic plate collections from around the world. First prize: $75,000 Second prize: $50,000 Third prize: $25,000 The competition accepts data from all pre-Sputnik photographic plate collections, except those from Palomar Observatory. Learn how to detect transien...
[Retweeted] On April 12, 1950, a Palomar telescope photographed 9 points of light that weren't there 30 mins earlier - before satellites were in orbit. Today we launch Project Lost Light: $150,000 for independent tests of these flashes in other plate archives. https://t.co/HskQQWO4gv https://t.co/Se5zUQpoMB
Probed ingest of: Former UAP Task Force Member: “We’ve Seen Better UAP Footage”
What lies beneath those weird likely artificial objects Dr Beatriz Villarroel and her colleagues detected in orbit? Mapping the Palomar transient hotspots | Our latest Reality Check interview with @DrBeaVillarroel & Dr Stephen Bruehl: https://t.co/eCpFXpaDRU via @YouTube
Probed ingest of: I Confront The Secretary of Energy On UFOs
[Retweeted] Our latest REALITY CHECK features astronomer Dr Beatriz Villarroel @DrBeaVillarroel and Dr Stephen Bruehl's latest ground-breaking paper exploring the Palomar orbital transient hotspots. What lay below these transients? https://t.co/8RgF3ym1gF
