Joaquim Hernandes wrote three books on this topic, he investigated the whole case thoroughy. HEAVENLY LIGHTS: The Apparitions of Fatima and the UFO Phenomenon, Celestial Secrets: The Hidden History of the Fatima Incident and Fatima Revisited: The Apparition Phenomenon In Ufology, Psychology, and Science create the Fatima Trilogy, in which the authors studied the whole case of this unexplained phenomena, reaching the facts that aren't typically exposed to people who naively believe that it was the Jewish teenager who two millenia ago gave birth without having had sex, previously, who appeared in Fatima. He got access to the read documents from Fatima, which were censored at the beginning. He investigated the details of the apparitions, which have a LOT of in common with what people who saw UFO's reported: the sounds of buzzing,heat waves, weird shaped "clouds" around, "angel hair" falling from the sky etc. The creature that the children saw was wearing a short, knee-length robe (remember: back then, showing your legs in the public when you were a woman was as shocking as now showing your bare breasts), was abnormally short and looked like a girl in her early teens. The image of it got distorted by in what way illiterate and religious people interpreted what they saw.