A waxing moon is one whose lit face is growing toward full, and a waning moon is one whose lit face is shrinking back toward new. That is the entire distinction. Everything else in the lunar month is a question of how far along the growing or the shrinking has got. Both words are older than the astronomy fastened to them: weaxan, to grow, and wanian, to lessen.
The cycle, in order
One lunar cycle runs 29.53 days, new moon to new moon, and eight named phases divide it up.
- New Moon. The Moon sits between us and the Sun with its lit face turned away. Nothing to see. The cycle begins here.
- Waxing Crescent. A returning sliver, low in the west just after sunset, gone within a couple of hours.
- First Quarter. Half the disc is lit. It is called a quarter because a quarter of the cycle has passed, not because a quarter is showing.
- Waxing Gibbous. More than half, not yet whole. Gibbous is Latin for humped, which is exactly what the shape does.
- Full Moon. Earth sits between the Sun and the Moon, the whole face is lit, and it rises as the sun goes down.
- Waning Gibbous. The same broad shape losing light from the other side, rising later each night.
- Last Quarter. Half lit again, the opposite half. It rises near midnight and is still up at breakfast.
- Waning Crescent. The final sliver, visible in the east before dawn, thinning away to nothing.
Half of 29.53 days is 14.77, so new moon to full moon takes roughly fourteen days and eighteen hours, and the journey back takes the same. Worth knowing: the four principal phases, new, first quarter, full and last quarter, are instants rather than days, the exact moment the geometry lines up. The four in between, the two crescents and the two gibbous stretches, each run about a week. That is why two calendars can print the full moon on different dates and both be right, since the instant falls either side of midnight depending on where you live.
Telling waxing from waning at a glance
In the northern hemisphere the light returns on the right hand side and leaves from the left. The old mnemonic is that the Moon spells DOC across the month: a D shape while it waxes, a full O, then a C while it wanes. South of the equator the whole picture is mirrored, and the Moon spells COD instead.
Timing gives the same answer without any shapes. A waxing moon is an evening moon, up after sunset and gone by dawn. A waning moon is a small hours moon, rising late and lingering into the morning. If the Moon is still there while you drink your coffee, it is waning.
What each half is for
The symbolism follows the astronomy honestly enough. The waxing arc, new moon to full, is the adding half: starting, courting, applying, planting, building toward something that is not there yet. The waning arc is the subtracting half: finishing, releasing, cutting back, clearing out, closing what is already open.
That is a frame, not a force. The Moon is not moving your life about. What it offers is a shape for the month, and a reason to do the right kind of work at the right end of it, which is more use than it sounds.
One thing worth keeping straight: the moon in tonight's sky is not your Moon sign. Your Moon sign is where the Moon stood at the hour you were born, and it never changes. Tonight's phase belongs to everyone alive at once. I have written about that difference in Sun, Moon, Rising.
Why a ceremony waits for the moon
This is where the phases stop being decorative. A Grand Ceremony reading at this table is not written on the day it is ordered. It is held on an elected date, chosen from a window of three to twenty one days after the order, and the moon decides half of it.
A love reading waits for a Full Moon, when what sits between two people is at its most visible, and better still for a Full Moon landing on a Friday, which is Venus's own day. A clarity reading waits for a New Moon, ideally a Wednesday, Mercury's day, because a dark sky and a clear head are the same request made twice. A reconciliation reading also waits for a New Moon, but on a Friday: the one phase where something can genuinely begin again, on the weekday that favours a returning heart. When the phase and the ruling weekday fall together, that is the date, and it goes on the Ceremony Record with the moon named on it.
None of that promises an outcome. An elected date does not make an answer kinder, and it will not bring anyone back. It means the reading was prepared at the point in the month that matches the question, rather than whenever the order happened to land, and that the keepsake names the night it was done.