space · FOLLOW YOUR CURIOSITY
The Moon is not changing shape. You are changing the view.
Move the Moon around Earth. Can you make the crescent disappear?
Explore the interactive discovery →
Make a month in a moment
Move through one full orbit.
New Moon
The lit half faces away from Earth.
Full Moon
The lit half faces Earth.
New Moon again
The same geometry returns.
Schematic geometry; not to scale. The slider follows an ideal orbit, not today’s real Moon.
What you just noticed
Sunlight illuminates half the Moon. Its orbit changes how much of that half we see. Ordinary phases are not Earth’s shadow.
Keep the distinction
See what happens
A phase is a changing view of sunlight on a sphere.
The lit half faces Earth.
AN IDEA TO TAKE WITH YOU
A phase is a changing view of sunlight on a sphere.
Follow a connection
Sources and transparency
NASA · Moon phases
Accessed: 2026-10-28
Royal Museums Greenwich · Moon phases
Accessed: 2026-10-28
Prepared with AI assistance. Illustrations are explanatory, not evidence. You can report an issue in the interactive discovery.