This belongs at r/ufos, not on a HN. To anyone who is new to this - one scientist, Beatrice Villarroel, promotes a theory that old photoplates from mid 20th century, show multiple UFOs because there were discrepancies between two pictures taken 50 minutes apart. To prove this, she makes analysis of several pairs of pictures where this is indeed observed. So, she's right?
First of all, in every par she picks arbitrary a tiny fraction, like a few percentages of an area of the plate, without any explanation why the rest of the image is ignored. After looking at the full plates, one can see that there not dozens of suspicious lights but literally thousands of disappearing lights, uniformly spread out across the whole plate, without any pattern or localization. So thousands of alien saucers all across the Earth. You see where this is going? But it gets worse.
Second - in all pairs of plates the lights change one way only. On the first plate they are present and on the next plate 50 minutes later they disappear. Not a single light out of thousands is breaking the pattern and transitions from empty to light, no, all of them transition from light to nothingness only.
And finally third - these thousands of UFOs on the first plate appear because the first plate uses a brittle and unstable red pigment. I can't quickly find out the source, but one guy did analysis and found out the type of the emulsion used on the first plates in these sets in that decade and said that it was indeed a fragile compound, which is most likely the reason for these thousands of uniformly spread out image defects.
tl;dr - ufologists as usually failed at basic reasoning, logic and knowledge of history.