Calculate the phase of the moon on a specific date based on lunar cycles. Find out if it's New, Full, or in between.

Calculate Moonphase on a Date

Purpose

The purpose of this function is to determine the phase of the moon on a specific date based on the assumption that the New Moon occurs every 29.53058770576 days.

Use Cases

• You can use this function to find out the current phase of the moon on a particular date.
• It can be used for astrological or astronomical purposes to track the moon's cycle.

How to Use

1. Enter the date for which you want to calculate the moon phase.
2. Click on the "Calculate" button to get the result.

Input Values

1. Date: Enter the date for which you want to calculate the moon phase. Default unit is day.

Output Values

1. Moon Age: This value represents the age of the moon in days.
2. Moon Phase: This value indicates the current phase of the moon (e.g., New, Waxing Crescent, Full, etc.).

Any other Instruction

• The calculation is based on the reference New Moon date of 06 January 2000 AD.
• The function uses a predefined lunar cycle length of 29.53058770576 days.

Steps of Calculation

1. Calculate the Julian day number for the input date.
2. Determine the day since the reference New Moon date.
3. Calculate the moon's age based on the lunar cycle length.
4. Determine the moon phase based on the moon's age.

Technical Parameter names

on_date

Return Values

Moon Age, Moon Phase

Example Expressions

You can use the following expressions to directly evaluate in a non-interactive manner using eva():

moonphase(date(2022, 10, 15))
moonphase(date(2023, 5, 20))

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