If you're "over the moon," you feel extremely happy or elated. This idiomatic expression is often used to describe a state of great joy or excitement. The phrase suggests that your emotions are so elevated that you feel as if you've transcended the ordinary and are metaphorically floating high above, much like being over the actual moon in your level of happiness.
The origin of this expression is believed to be tied to nursery rhymes and literature, where whimsical and exaggerated imagery is often used to convey feelings. For example, in the nursery rhyme "Hey Diddle Diddle," there's a line about the cow jumping over the moon, which reinforces the idea of achieving the seemingly impossible, much like the feeling of overwhelming joy.
In everyday use, saying you're "over the moon" might describe feelings you experience after receiving great news, achieving a significant personal goal, or experiencing a moment of pure delight, such as the birth of a child, getting a promotion, or even something simple like hearing your favorite song. This phrase is a vivid way to communicate the depth and intensity of one's happiness.