🌙 Moon Phases
🌙 Moon Phases — Why the Moon Changes Shape
Why does the Moon look different every night? Discover that the Moon never actually changes shape — what changes is how much of the sunlit side we can see from Earth.
🔬 What It Demonstrates
The Moon orbits Earth every 29.5 days. As it moves, different proportions of the sunlit half face Earth: New Moon (dark side toward us), Full Moon (lit side fully facing us), and all phases in between.
🎮 How to Use
Drag the Moon around its orbit and watch the phase change. Click Fast Forward to speed up to 1 day per second and see the full 29.5-day cycle. Toggle Sun rays to understand each phase.
💡 Did You Know?
The Moon is moving away from Earth at 3.8 cm per year. 1.4 billion years ago it was much closer, causing tides 10× higher than today. Eventually the Moon's orbital period and Earth's day will synchronise at about 47 days — billions of years from now.