One of Bonilla's photographs.
On August 12, 1883, the astronomer José Bonilla reported that he saw more than 300 dark, unidentified objects crossing before the Sun while observing sunspot activity at Zacatecas Observatory in Mexico. He was able to take several photographs, exposing wet plates at 1/100 second. These represent the earliest photos of an unidentified flying object. It was later suggested that the objects were actually high flying geese, while some ufological literature interpreted the objects as either alien spacecraft or an unsolved mystery.
In 2011, researchers from the National Autonomous University of Mexico suggested that the unidentified objects may have been fragments of a billion-ton comet passing within a few hundred kilometers of Earth.