The phase of the moon is how much of its face is lit as seen from Earth — from new, through the quarters, to full and back in about 29.5 days.

The lit fraction follows the angle between sun and moon; the age counts the days since new. The same face always turns toward us, so the phase is the sun's light moving across it, not the moon turning. Sol draws tonight's moon at its true phase and tilt for where you stand.

Waxing when the lit side grows and the moon is an evening sight; waning when it shrinks and belongs to the small hours.