Moon Calculator 6.0

How to Use This Calculator

Using Moon Calculator 6.0 is simple:

1. Enter the date you want to calculate
2. Select your location (latitude and longitude)
3. Click "Calculate" to get results
4. Review the lunar phase, illumination percentage, and moonrise/moonset times

The calculator provides a visual representation of the moon's phase and illumination percentage, along with precise timing information for moonrise and moonset events.

Formula Used

The calculator uses the following astronomical algorithms to determine lunar phases and illumination:

The calculator also accounts for the observer's location (latitude and longitude) to calculate accurate moonrise and moonset times.

Worked Example

Let's calculate the moon phase for June 21, 2023 at 00:00 UTC:

1. Convert the date to Julian Date: JD = 2460112.5
2. Calculate Moon Phase: (2460112.5 - 2451550.1) / 29.530588853 ≈ 2.5 (Full Moon)
3. Calculate Illumination: (1 + cos(2π * 2.5)) / 2 * 100 ≈ 99.9%
4. Determine Moonrise/Moonset times based on location

This calculation shows a nearly full moon with 99.9% illumination, which is typical for a Full Moon phase.

Interpreting Results

The calculator provides several key pieces of information:

• Lunar Phase: The current phase of the moon (New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Waning Crescent)
• Illumination Percentage: The percentage of the moon's visible disk that is illuminated by sunlight
• Moonrise Time: The time when the moon becomes visible above the horizon
• Moonset Time: The time when the moon disappears below the horizon

These values are essential for astronomical observations, photography, and planning outdoor activities that depend on moonlight.