Does 0.0% illumination indicate the time of Conjunction?

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).

Related Content: