The Moon

One Cycle, Eight Names

The Moon takes about twenty-nine and a half days to run from one new moon to the next, and the phases are simply named points along that continuous change. Nothing happens at a phase boundary; the names are a convenience for talking about a gradient.

Four of the eight are precise astronomical moments — new, first quarter, full and last quarter — each defined by an exact angle between the Sun, the Earth and the Moon. The other four are the stretches between them, lasting about a week each.

The Moon produces no light of its own. What changes across the month is how much of its lit half faces us, which depends entirely on where it sits relative to the Sun from our vantage point.

What Each Half Of The Cycle Does

Waxing runs from new to full, with the lit portion growing. The tradition attaches it to building, beginning and accumulating — a fortnight read as gathering momentum.

Waning runs from full back to new, with the light retreating. It is associated with completion, release and clearing, which is why the older folk practices put finishing tasks in this half.

The two turning points carry the most weight. New moons are read as openings, full moons as culminations, and most lunar practice organises itself around those two dates rather than around the phases between them.

Reading The Phase Against The Sign

Phase and sign are separate measurements and are confused constantly. The phase says how lit the Moon is; the sign says where it sits along the zodiac.

They run on different clocks. The sign changes every two and a half days, the phase over twenty-nine and a half, and any phase can occur in any sign — a full moon in Scorpio and a full moon in Taurus are the same phase in different places.

Practitioners who work with the lunar calendar read both together, which is where the more specific interpretations come from. A new moon in Capricorn and one in Pisces are read as openings of quite different kinds.

Eclipses And Supermoons

An eclipse is a phase that happens to occur when the Moon is also near one of the two points where its orbit crosses the Earth's. Solar eclipses happen at new moons, lunar eclipses at full moons, and both come in seasons roughly every six months.

A supermoon is a full moon near the closest point of the Moon's orbit. It is genuinely larger in the sky, by around seven per cent against average, which is a real difference and one almost nobody can detect by eye.

Neither is astrologically special in any way the tradition can support, whatever the coverage suggests. They are ordinary phases with additional geometry.

What The Phases Do Not Affect

No phase of the Moon affects health, sleep, mood, fertility or behaviour. The full-moon studies are among the most thoroughly conducted in the field and they consistently find nothing.

The tidal argument does not survive contact with the numbers. Tides work on ocean basins and the effect on a body of water the size of a person is far smaller than the effect of standing up.

What the phases do supply is a shared calendar, which is a real and modest thing. Marking a month by something visible in the sky is useful; expecting it to act on you is not.

Common Questions

How long is the full cycle? About twenty-nine and a half days from new moon to new moon. That is the synodic month, and it is slightly longer than the twenty-seven and a third days the Moon takes to circle the zodiac.

Why is the Moon sometimes visible in daytime? Because it is above the horizon for roughly twelve hours of every day regardless of phase. Away from full, it is often up while the Sun is.

Are there really thirteen full moons some years? Yes. Twelve cycles come to about three hundred and fifty-four days, so a thirteenth full moon fits into most third years. The extra one is the blue moon.