Why does the moon change shape every night?
Quick Answer: The moon changes shape every night because we see different parts of its sunlit side as it orbits Earth. This cycle, called the lunar phases, happens as the moon moves around us, showing varying amounts of light from new moon to full moon and back.
The moon doesn’t actually change shape. Instead, the sunlight reflects off different portions of its surface as the moon circles Earth. When the side facing us is mostly dark, that’s a new moon. When it’s fully lit, that’s a full moon.
This cycle takes about 29.5 days to complete. Each night, the angle between the sun, moon, and Earth shifts, changing how much of the moon’s bright side we can see. That’s why the moon looks like it’s growing, shrinking, or even disappearing at times.