I'm trying to find a technical explanation for an object I personally observed in Novi Sad, Serbia. This happened at approximately 20:32 in the evening. The sun had already set or was very close to setting. There were no direct sun rays, but it was not completely dark yet, and visibility was still good. What I observed: The object appeared to be an almost perfect sphere. Its color was light gray or milky white. The surface looked matte rather than shiny. At one point it passed roughly 5 meter...