2010 California contrail incident

On the evening of Monday, November 8, 2010, an unusually conspicuous contrail appeared about 35 miles (56 km) west of Los Angeles, California, in the vicinity of Catalina Island. News footage of the event from a KCBS helicopter led to intense media coverage and speculation about a potential military missile launch, with many reporters and experts discussing the vapor trail and theorizing about its source.

Source: Wikipedia — 2010 California contrail incident (CC BY-SA 4.0)