* The "Dark Side" of the Moon: While we often call it the "dark side," it's not always dark. Both sides of the moon receive sunlight, but we only ever see one side from Earth. The other side is called the "far side" of the moon.
* The New Moon: During the new moon phase, the moon is positioned between the Earth and the Sun. Its illuminated side is facing away from us, so we can't see it.
* A Moon Covered by Clouds: Even if the moon is in a visible phase, it can be hidden from view if clouds are blocking it.
So, there's no single "invisible" moon. It depends on what you mean by "not visible"!
