The eight phases of the Moon
The Moon's phase is simply the angle between the Sun and the Moon as seen from Earth. At new moon they are together and the side facing us is dark; at full moon they are opposite and we see the whole lit face. The cycle takes about 29.5 days, the synodic month.
| Phase | Angle from the Sun | What you see |
|---|---|---|
| New Moon | 0°, give or take 22° | Nothing: the Moon is lost in the Sun's glare |
| Waxing crescent | 22° to 68° | A thin, growing sliver in the evening |
| First quarter | 90°, give or take 22° | The right half lit (in the northern hemisphere) |
| Waxing gibbous | 112° to 158° | More than half, growing |
| Full Moon | 180°, give or take 22° | The whole face, rising at sunset |
| Waning gibbous | 202° to 248° | More than half, shrinking |
| Last quarter | 270°, give or take 22° | The left half lit, high at dawn |
| Waning crescent | 292° to 338° | A thin sliver before sunrise |
The new, full and quarter moons are exact moments, but the Moon looks much the same for a day or two around each, so the calculator gives each of the eight names to an eighth of the cycle and shows the exact angle and the percentage of the disk that was lit. In the southern hemisphere the same phase looks mirrored: the waxing Moon is lit on the left.
Your birth moon in astrology
In a birth chart the Moon's phase adds a layer to your Moon sign: where the sign describes the style of your emotional life, the phase describes the stage of the Sun–Moon cycle you arrived in. Following the astrologer Dane Rudhyar, many astrologers divide that cycle into eight lunation types, each an eighth of the way from one new moon to the next:
- New Moon type (0° to 45°): instinctive, forward-moving, a starter.
- Crescent (45° to 90°): determined to break free of the past and build something new.
- First Quarter (90° to 135°): a doer, decisive and drawn to challenges.
- Gibbous (135° to 180°): an improver, analytical and devoted to getting things right.
- Full Moon (180° to 225°): aware of others and of meaning; relationships are central.
- Disseminating (225° to 270°): a sharer, passing on what they have learned.
- Last Quarter (270° to 315°): a reformer, quick to question old forms.
- Balsamic (315° to 360°): reflective and future-minded, finishing old cycles.
These readings describe astrological tradition, not measured personality traits. They are for reflection, and the calculator gives the one for your birth.
New moons, full moons and your birthday
Along with the phase at your birth, the calculator lists the new and full moons on either side of it, to the minute, in your local time when you give a birth place. It also shows the Moon on your next birthday. The phase returns to nearly the same calendar date every 19 years, a rhythm known since antiquity as the Metonic cycle, so your 19th, 38th and 57th birthdays come with nearly the Moon you were born under.
Phase, sign and the rest of the sky
The phase and the Moon sign are separate things: any sign can come with any phase. The Moon passes through all twelve signs in about 27 days, a little faster than it runs through its phases, so the pairing shifts from month to month. To see the whole sky at your birth, open your birth chart; to see the planets moving now against it, try the transit chart.