Estimate the Moon's illuminated fraction from a calendar date.
| Illuminated % | – |
Use this for a diary, a photo plan, or a garden note. Illumination uses a 29.53-day synodic clock from a known new moon (2000-01-06). 0% is new, 100% is full, 50% is a quarter. Rise times, libration, and eclipses are not included. Fine for a journal, not for navigation.
Date: Civil date (YYYY-MM-DD).
Illuminated %: Approximate sunlit fraction of the disc.
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