How can you determine whether the Moon is waxing or waning?

To determine whether the Moon is waxing or waning, observing its size is a key factor. When the Moon is waxing, it is increasing in illumination and visibility, moving from a new moon toward a full moon. During this phase, the illuminated portion appears to grow larger each night. Conversely, when the Moon is waning, it is decreasing in illumination and visibility, moving from a full moon back to a new moon; this means the illuminated portion appears to shrink over time.

The size of the Moon observed in the night sky provides immediate visual cues about its phase, reflecting how much sunlight is being reflected off its surface as it orbits Earth. In this context, larger appearances of the Moon indicate it is waxing, while smaller appearances signal it is waning. This visual perception aligns with the lunar cycle and is fundamental in understanding the Moon’s phases.