The Moon's phase is simply the angle between the Moon and the Sun. That angle completes a full turn every 29.5 days, and it determines the shape we see. Traditional timing cares a great deal about which half of the cycle you are in.
The Moon makes no light of its own; it reflects the Sun's. The lit portion we see from Earth depends on where the Moon stands relative to the Sun.
This is the synodic month, averaging 29 days, 12 hours and 44 minutes. Note the word average: the Moon's orbit is elliptical, so each cycle runs slightly long or short.
This is the most basic distinction in traditional timing:
| Half | Range | Traditional leaning |
|---|---|---|
| Waxing | New → Full | Starting, growing, gathering, adding |
| Waning | Full → New | Finishing, reducing, removing, clearing |
Moon Compass uses this in its Best Time Finder: tasks about beginning — a contract, a move — score for a waxing Moon, while tasks about removal score for a waning one.
| Phase | Illumination | Traditional sense |
|---|---|---|
| 🌑 New Moon | 0% | Intention, seed. Nothing visible yet. |
| 🌒 Waxing Crescent | 1–45% | First step, setting out. |
| 🌓 First Quarter | 50% | Resistance and decision; the test of persistence. |
| 🌔 Waxing Gibbous | 55–99% | Refinement, improvement. |
| 🌕 Full Moon | 100% | Visibility, peak, the result showing itself. |
| 🌖 Waning Gibbous | 99–55% | Sharing, passing on, telling. |
| 🌗 Last Quarter | 50% | Review, the decision to let go. |
| 🌘 Waning Crescent | 45–1% | Rest, recovery, closure. |
Because a Full Moon is not a day — it is an instant: the second when the angle between Moon and Sun is exactly 180° (or 0° for a New Moon). A calendar may say "Full Moon, 14 September", but the actual peak falls at a particular minute of that day.
Moon Compass finds that instant by computing the real positions of the Moon and Sun and searching for the moment the angle crosses its target, then converts it to your chosen city's time zone. The same Full Moon therefore reads 13:04 in Ankara and 10:04 in London — one instant, two local clocks.