According to "The Circulatory System" by Regina Avraham each day the heart creates enough energy to drive a truck 20 miles. Over the course of a "lifetime" (70-80 years) this is enough to get you to "the moon and back".
So, in a way, when you tell someone you "love them to the moon and back" you're telling them you love them with every beat of your heart. Moreso, every beat your heart has had and will ever have.
So, in a way, when you tell someone you "love them to the moon and back" you're telling them you love them with every beat of your heart. Moreso, every beat your heart has had and will ever have.
Which is a pretty long way compared to us humans.
Regardless, that's hella far away