Wide or wild blue yonder

In both formats, these American expressions refer to the open sea or sky, in the sense of far and indeterminate distances. They derive from the opening words of the official song of the US Air Force written by Robert Crawford in 1939. Strictly speaking, the expression is ‘wild’ blue yonder but it frequently appears as ‘wide’ blue yonder. The opening words of the song are in fact, “Off we go into the wild blue yonder.”