Earlier this month, Twitter CEO Dick Costolo said, “We have things rolling out this fall that I am over the moon about and can’t wait for people to see.” The week before, race car driver Scott Dixon said he was “over the moon” about winning the Firestone 600.
“Over the moon” is of course a metaphorical way of saying you’re happy and excited. The Oxford English Dictionary’s first citation is from 1936. It’s not unfamiliar to Americans, but it’s traditionally been more common in Britain, as this Google Ngram Viewer chart shows:
In recent years, it’s mainly been the province of British and Australian celebrities talking about being pregnant or having a child, or athletes talking about winning a game. Such uses still yield the majority of Google News hits, such as Perth Now’s that an Australian businessman’s girlfriend has a baby bump: “’I’m over the moon. It’s the most wonderful thing that’s ever happened to me,’ the proud expectant dad told us exclusively.'”
But the Costolo and Dixon quotes suggest that “over the moon” will follow the lead of “at the end of the day” (which I see to my horror that I’ve never done an entry on) and become established in the U.S.