But perhaps nothing so apparently unworldly as this.
The captain of a Thomas Cook airliner flying tourists back from the Spanish holiday island to the north of England reported a "near miss" with a "rugby ball"-shaped UFO, which passed within feet of his jet.
The encounter, over Reading, Berks, was reported to the aviation authorities, who launched an investigation. But no earthly identity for the object could be established.
The jet was flying to Manchester International airport, from Ibiza, on July 19th 2013. For years, the island has enjoyed a hedonistic reputation, attracting thousands of tourists each summer, many attracted to its vibrant nightlife. In recent years, it has attracted an increasingly upmarket clientele, among them David and Samantha Cameron.
The aircraft was flying at 516mph, at an altitude of 34,000ft, when it was passed by the UFO.