An international collaboration of astronomers has identified a curious occurrence of nine star-like objects that appeared and vanished in a small region within half an hour... Scientists from Sweden, Spain, the US, Ukraine, and India... investigated...photography that used glass plates to capture night sky images of April 12, 1950, exposed at the Palomar Observatory in California. They detected these transient stars, which were not to be found in photographs half an hour later and not traced since then. The astronomers have not found any explanation in well-established astrophysical phenomena like gravitational lensing, fast radio bursts or any variable star that...