Over the Moon is a widely popular colloquialism, used for expressing one is Happy as a Clam.
Although the exact origin of the expression is not known, it dates back to the 16th or 17th centuries.
An early example of the phrase can be found in the 1641 publication “A Stage-Player’s Complaint” where the “Over the Moon” is used in a similar manner as it is in contemporary contexts.
Another likely source for the colloquialism is the popular nursery rhyme “Hey, Diddle, Diddle” which first appeared in print 1760, however, the starting line of the rhyme was the name of a popular dance in the 1590’s.
“Over the Moon” was also included in Charles Molloy’s 1718 play “The Coquet or The English Chevalier”.
Although the exact origins for the phrase “Over the Moon” are debated, its widespread usage throughout the centuries is undeniable.
It has been around in plays and nursery rhymes for half a millennium already, and it has been used colloquially to express happiness and excitement since the late 1700’s.
“Over the Moon” is incidentally also the title of a 2020 Netflix animation film.
The expression was first defined on Urban Dictionary on December 19th, 2006, with several other entries to follow.