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About the Lunar Calendar

The Lunar Calendar tool provides a beautiful and scientifically accurate way to explore the phases of the Moon. Using data from NASA's Scientific Visualization Studio, this tool lets you see what the Moon looked like—or will look like—at any moment in time. It's a fascinating resource for astronomers, educators, gardeners, and anyone curious about our closest celestial neighbor.

Powered by NASA's Dial-A-Moon

This tool fetches data directly from NASA's Dial-A-Moon service, ensuring you receive the most accurate information available. For any given date and time, you can see not only a visual representation of the Moon but also detailed ephemeris data, including:

• Illumination: The percentage of the Moon's visible surface that is lit by the Sun.
• Age: The number of days that have passed since the last New Moon.
• Distance: The distance from the center of the Earth to the center of the Moon in kilometers.
• Apparent Diameter: The angular size of the Moon in the sky.

Understanding the Phases

The Moon's phase is determined by its position relative to the Earth and the Sun. As the Moon orbits our planet, the amount of its sunlit side that we can see changes, creating a cycle of phases that repeats approximately every 29.5 days. This cycle, from New Moon to Full Moon and back again, is known as a synodic month or lunation.

Related Tools

Many traditional calendars, like the Hijri Islamic Calendar and Hebrew Calendar, are based on the cycles of the moon. You can also explore the Earth's relationship with the Sun in our Solar Calendar.