Enter the number of days since the last new moon into the calculator to determine the current moon phase percentage. This calculator helps to estimate how much of the moon is illuminated at any given time in the lunar cycle.
Moon Phase Percentage Formula
The following formula is used to calculate the moon phase percentage:
MPP = ((DSNM / 14.765) * 100) for DSNM ≤ 14.765
MPP = (((29.53 - DSNM) / 14.765) * 100) for DSNM > 14.765
Variables:
- MPP is the moon phase percentage (%)
- DSNM is the number of days since the new moon
To calculate the moon phase percentage, use the formula above, which changes depending on whether the number of days since the new moon is less than or equal to half the synodic month (14.765 days) or greater than half the synodic month.
What is Moon Phase Percentage?
Moon phase percentage indicates the fraction of the moon's disk that is illuminated by the sun and visible from Earth. The percentage varies in a predictable cycle as the moon orbits the Earth, and it can range from 0% (new moon) to 100% (full moon). Understanding the moon phase percentage is useful for various purposes, including astronomy, navigation, and planning outdoor activities at night.
How to Calculate Moon Phase Percentage?
The following steps outline how to calculate the Moon Phase Percentage.
- First, determine the number of days since the new moon (DSNM).
- Next, use the formula based on whether DSNM is less than or equal to 14.765 days or greater than 14.765 days.
- Finally, calculate the Moon Phase Percentage (MPP).
- After inserting the variable and calculating the result, check your answer with the calculator above.
Example Problem:
Use the following variable as an example problem to test your knowledge.
Number of days since the new moon (DSNM) = 10 days