Strange sighting in the night sky

UFO

Often reported by witnesses but rarely confirmed by official investigations.

This clue plays on the idea of something unusual seen in the sky after dark. "Strange sighting" hints at something out of the ordinary, while "night sky" points to celestial objects—here, specifically an unidentified flying object, or UFO. The term is widely recognized in pop culture as a shorthand for mysterious aerial phenomena, making it a straightforward but clever fit. No tricky wordplay, just a direct nod to a familiar concept.