Question: Why does the App sometimes show New Moon Day commencing when the illumination of the moon is at 0.0%? Does 0.0% illumination not indicate the time of Conjunction? If it does, shouldn't New Moon Day be the following day?
Answer: Because the App only shows one decimal place for the illumination, it does not necessarily indicate the precise moment of Conjunction. For example: When the moon's illumination is 0.01%, it will still show as 0.0%. For this reason, the App will display 0.0% illumination for a brief period both before and after the precise moment of Conjunction.
The app uses USNO calculations for conjunction (astronomical new moon).
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