Space Hall · EXH-0003
Why does the Moon look different each day?
The Moon is always round, yet the bright shape we see changes night by night.
Start the experience01
What should you look for?
What changed when the Moon moved?
- 01The sunlit half still faced the Sun
- 02Earth saw a different fraction of the bright half
- 03The Moon rotated once while orbiting once, keeping nearly the same face toward Earth
02
Why does this happen?
Half is always sunlit
Except during an eclipse, sunlight illuminates half of the Moon at every orbital position.
Our viewing angle changes
As the Moon orbits Earth, we see different amounts of that sunlit half. Ordinary phases are not Earth’s shadow.
Orbit and rotation stay in step
The Moon rotates once in the same direction during one orbit, so nearly the same lunar face keeps pointing toward Earth.
The 3D model keeps the Sun direction fixed, places Earth at the orbit center, links one lunar rotation to one orbit, and visualizes the orbit with about a 5° tilt. Earth’s orbit around the Sun is omitted.
03
Move it before reading the answer
Change the orbital position, then compare the sunlit side with the view from Earth.
Science source
Moon PhasesNASA Science ↗