76 years after Palomar photographed nine “stars” that vanished, an open challenge wants to settle whether they were real

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...

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