This app allows you to visually learn about the different phases of the moon depending on the positions of the moon, the Earth, and the Sun.

The app has undergone a major overhaul to improve its features!

Why does the moon have different phases?
Why does the height of the Sun change depending on the season?
These diagrams provide easy answers to these questions!

You can intuitively grasp the positions of the Sun, the Earth, and the moon through overhead and celestial sphere diagrams!

What are the positions of the Sun and the moon during a full moon?
Where is the Sun when the waning crescent transits the meridian?

You can answer these questions by turning the dial and checking their positions!


※The size and distance of celestial objects are not drawn to scale but exaggerated for easier understanding.
※For easier understanding, the Earth's orbit is made circular instead of elliptic while the inclination of the moon's orbit has been omitted.