They do not match known stars or galaxies in modern catalogs. They also predate Sputnik, meaning they cannot easily be explained as glints from ordinary satellites or space debris, News.Az reports, citing ZME Science.
For years, the simplest answer has been the most deflating one: old photographs are known for their defects. Dust, scratches, hairs, emulsion flaws, scanning errors, and other plate defects can smudge the resulting photographs, leaving artifacts that may depict things that were never in the picture to begin with. So maybe these “transients”, as astronomers call them, were just grime.
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But a new study argues that the plate defect explanation no longer fits comfortably and that at least some of the flashes are harder to dismiss. The team used machine learning to sort more than 107,000 candidate flashes from the first Palomar Observatory Sky Survey and estimate which ones were most likely to be real objects rather than plate defects.
The analysis suggests that most of the Palomar transients are probably junk, but at least 10% of the candidates look genuine with a probability exceeding 80%. So, the new study strengthens the claim that some pre-Sputnik Palomar flashes were real, unexplained transient phenomena.
That does not mean the authors have found alien probes, secret pre-Sputnik satellites, or any other extraordinary object. They say the nature of the flashes remains unknown, although the new study found that the most convincing flashes are less common in Earth’s shadow and are more common around US nuclear test dates.
