Richard Rodgers and Lorenz Hart wrote this for the 1934 movie Manhattan Melodrama. Rodgers and Hart wrote many songs for Broadway plays, including The Lady Is A Tramp and My Funny Valentine. In 1948 a movie was made about the duo called Words And Music. It starred Mickey Rooney as Lorenz Hart.
This was also used in the movies Words And Music (1948); Malaya (1949); East Side, West Side (1950); and With A Song In My Heart (1952) before Elvis Presley recorded it for Sun Records in 1954.
The Marcels recorded this at the last minute when they recorded three songs and needed a fourth. When one of the members said he knew "Blue Moon," producer Stu Phillips told him to teach the song to the rest of the group in an hour, then they'd record it.
The introduction to the song was an excerpt of an original song that the group had in its act - Phillips added it to "Blue Moon" to give it a flair that the group was lacking in their other songs.
The Marcels recorded this in 2 takes. A promotion man asked and got a copy of the finished tape, which found its way to legendary DJ Murray The K. He promoted it as an "exclusive," and played it 26 times on one show.
The followup song, "Summertime," recorded a month after this, stalled at #78. Eight months later, the group hit #7 with "Heartaches," a song that begins with "Watch out! Here we go again..." Guy Lombardo took it to #12 in 1931 and Ted Weems topped the charts with it in 1947. (thanks, Brad Wind - Miami, FL, for all above)
Richard Rodgers hated the Marcels' doo-wop arrangement of this song so much that he took out advertisements in the music papers urging people not to buy it. (thanks, Emery - London, England)
This has been covered by a slew of artists, including Louis Armstrong, Tony Bennett, and Django Reinhardt.
Sam Cooke recorded a little-known version of this. It was on the LP The Wonderful World of Sam Cooke under the label KEEN. The rare 45 rpm recording of this song was on the rainbow KEEN label. (thanks, Tracy - Beaumont, TX)
In the movie Grease this was used in a scene at the dance where it was interrupted by students "mooning." (thanks, Sharon - New York, NY)