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Birth moon phase
The 8 phases and what tradition says about each
| Phase | Slice of the cycle | Traditional reading |
|---|---|---|
| 🌑 New moon | day 0 | Beginnings, intention, seed |
| 🌒 Waxing crescent | day ~3.7 | Building, first momentum |
| 🌓 First quarter | day ~7.4 | Decision, action under tension |
| 🌔 Waxing gibbous | day ~11.1 | Fine-tuning, almost there |
| 🌕 Full moon | day ~14.8 | Fullness, harvest, visibility |
| 🌖 Waning gibbous | day ~18.5 | Gratitude, sharing the yield |
| 🌗 Last quarter | day ~22.1 | Review, forgiveness, release |
| 🌘 Waning crescent | day ~25.8 | Rest, closing the cycle |
This one is real astronomy (and we love it)
Unlike the other pages in this section, the moon phase on your birth date is a verifiable astronomical fact. The math uses the synodic month of 29.53059 days: we count how many days passed between the reference new moon of January 6, 2000 (18:14 UTC) and your date, take the remainder of the division by 29.53059, and that is the age of the moon on your birthday. This is why the same date lands on a different phase every year: 365.25 days is not a multiple of 29.53, so the phase drifts about 11 days per year. We validated the algorithm against full moons with documented eclipses (January 21, 2000 and September 28, 2015, plus the blue supermoon of August 31, 2023) and it gets the day right; without birth time and timezone, the honest margin is about 1 day around phase changes. In the southern hemisphere the moon looks mirrored, but the phase is the same.
Transparency: the phase itself is science; the meanings in the table are cultural tradition, not science, and are labeled as such. Privacy: the whole calculation runs on this page, your name and date never leave your browser.
Last updated: · Methodology and sources