How is the lunar illumination percentage calculated?

The moon phase calculator uses astronomical calculations based on the moon's position relative to Earth and the Sun. This determines the visible illuminated portion of the moon for any selected date and time.

Can I check historical moon phases?

Yes. You can select past or future dates to view historical moon phases, lunar age, and illumination percentage instantly.

A Supermoon occurs when a Full Moon appears closer to Earth during its orbit, making it look slightly larger and brighter in the sky.

Why does the moon appear flipped in the Southern Hemisphere?

People in the Southern Hemisphere view the moon from a different orientation, causing the illuminated portion to appear visually flipped compared to the Northern Hemisphere.

Does this moon phase calculator work on mobile devices?

Yes. The moon phase calculator works on desktop computers, tablets, and mobile devices directly in your browser.

Moon Phase Calculator | Lunar Age, Illumination & Moon Cycles

100% Browser-Based • Local Processing

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Illumination --% Fraction of surface lit

Lunar Age -- Days Synodic cycle progress

Distance -- km Earth to Moon center

Zodiac Sign -- Current Constellation

Next Full Moon --

Next New Moon --

Explore Lunar Cycle Timeline

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Astronomical Tracking

Understand the Night Sky Accurately

Are you an astrophotography enthusiast, a camper planning a night under the stars, or simply someone fascinated by the night sky? Understanding the lunar cycle is essential, but static calendars often fail to provide the full picture. Our interactive moon phase calculator solves this by instantly visualizing the exact current moon phase, lunar age, and illumination percentage based on real-time astronomical algorithms.

Whether you need to find the exact sunrise and sunset time to pair with a moonrise, or you want to check if tonight features a Supermoon, this tool gives you precise, immediate answers. Because it processes everything locally in your browser, your data remains completely private. There are no uploads, no delays, and no tracking. You can effortlessly switch between Northern and Southern hemisphere views or explore upcoming phases like the next Full Moon or New Moon seamlessly.

Quick Guide

How to Use the Moon Tracker

Using the calculator is intuitive and designed for both casual users and astronomy enthusiasts.

Step 1: Set Your Date

Start by selecting your target date using the calendar input at the top. The observatory will instantly calculate the lunar positioning for that day. If you want to jump back to the present moment, simply click the 'Now' button. You can easily pair this with our calendar generator to plan out a full month of stargazing and observation.

Step 2: Read the Telemetry

Analyze the data dashboard to see the exact illumination percentage, lunar age in days, and the distance between the Earth and the Moon. The tool automatically detects special events like Supermoons or Micromoons, giving you immediate context on whether tonight's moon will be exceptionally bright or slightly smaller than usual.

Step 3: Explore the Timeline

Use the horizontal Lunar Cycle Explorer to scrub through the days seamlessly. You can drag left or right to preview upcoming weeks. This is highly useful when planning a trip and pairing it with an event countdown timer to guarantee you schedule your activities on a perfect dark-sky night.

Knowledge Base

Frequently Asked Questions

Is my location data tracked to calculate the moon phase?

No, your location and selected dates are never tracked. The calculator runs 100% locally in your browser, relying on your device's system clock and mathematical formulas rather than pinging an external server. This guarantees total privacy and zero latency.

How does the hemisphere toggle work?

While the moon phase itself (like a Full Moon) is a global event, its visual orientation changes depending on where you stand on Earth. The hemisphere toggle flips the visual render so it matches what you see in the sky, whether you are in North America or Australia.

What is the difference between lunar age and illumination?

Lunar age is the number of days that have passed since the last New Moon, progressing up to approximately 29.5 days. Illumination is the physical percentage of the moon's surface currently lit by the sun.

Can I use this for historical moon phases?

Yes. You can use the date picker to go back to any date in the past or forward into the future to see exactly what the moon looked like or will look like on that specific day. It's an excellent tool to pair with a birthday calculator to discover the moon phase on the day you were born.

What exactly constitutes a Supermoon?

A Supermoon occurs when a Full Moon coincides with the moon's closest approach to Earth in its elliptical orbit, known as perigee. Because it is closer, it appears slightly larger and brighter than a standard full moon in the night sky.

Still have questions?

If you can't find the answer you're looking for, feel free to contact our support team.

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Interactive Moon Phase Calculator & Lunar Tracker

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Understand the Night Sky Accurately

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Interactive Moon Phase Calculator & Lunar Tracker

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