The Moon has no light of her own. What we see is sunlight on her near side, and what we call her phase is the angle between her and the Sun as seen from the Earth. At the New Moon she stands with the Sun, her lit side turned away, and we see nothing. At the Full Moon she stands opposite, and we see all of it. In between, the light grows along one edge and then shrinks from the same edge, and the whole round takes twenty-nine days, twelve hours, and forty-four minutes on average.
That round is a lunation, and astrologers divide it into eight phases. Four are cardinal, exact minutes when the angle between Moon and Sun is zero, ninety, one hundred eighty, and two hundred seventy degrees: the New Moon, the First Quarter, the Full Moon, and the Last Quarter. Four are the stretches between them: the Waxing Crescent, the Waxing Gibbous, the Waning Gibbous, and the Waning Crescent. Moondark names the minute of each cardinal phase, the Moon’s degree at that minute, and the image for that degree, and it shows which of the eight the Moon is in right now on the Now screen and the Moon tab.
The word gibbous means humped and describes the Moon when she is more than half lit but less than full. Crescent describes her when she is less than half lit. Waxing means growing, waning means shrinking, and in the northern hemisphere the light grows on the right and leaves from the right; in the southern hemisphere it is the other way round, and Moondark draws the Moon the way she looks from where you are.
Astrologers have read the lunation as a small life for as long as there have been astrologers: conceived in the dark, growing, seen in full, and released. The practice that comes from that reading is a rhythm rather than a set of rules. Begin at the New Moon. Build through the waxing half. Look at what you have made at the Full. Release through the waning half. Moondark’s Moon tab says what each phase is in the sky and what astrologers have read it as being for, and it leaves the reader to decide whether her own month keeps that time.
Two things are worth knowing about the phases and the void. The phase is about the Moon’s angle to the Sun; the void is about her aspects to all the bodies and her sign. They are independent. A Full Moon can be void, and a void can fall at any phase. Moondark reads them separately, shows them separately, and never lets one stand in for the other.