What indicates that the Moon is in a waning phase?

When the Moon is in a waning phase, it means that the illuminated part of the Moon visible from Earth is decreasing each night. This happens after a full moon when it transitions to the last quarter and then to a new moon. As the illuminated surface diminishes, we observe less of the Moon's lit portion each evening. This is why the appearance of the Moon is smaller each night during the waning phase.

In contrast, a waxing phase occurs when the Moon appears larger each night, indicating that it is transitioning from a new moon to a full moon. The completely dark state refers to the new moon phase, whereas being fully lit describes the full moon phase, neither of which indicates that the Moon is waning.