← All experimentsSPACE AND EARTH · AGES 6+

Moon Phases

Watch the visible sunlit part of the Moon change.

THE MOON WATCH LAB

One Moon, many views.

Move around Earth and discover why the Moon seems to change shape.

LEARNING LEVEL

SPACE VIEW · MOVE THE MOONSUNLIGHT →

VIEW FROM EARTH

New MoonAbout 0% of the visible disc is sunlitThe lit part grows

Move through the cycleDay 0.0 / 29.5

NewFirst quarterFullLast quarterNew

Animation speed

A simplified 29.5-day cycle, not today’s actual Moon. Drag, use the slider or keyboard arrows, or play the orbit.

EXPLORE · MOON WATCH

What can you see?

Move the Moon and compare its position with the view from Earth.

YOUR OBSERVATIONNew Moon

The sunlit half faces mostly away from Earth.

Try moving from new Moon to full Moon. What happens to the part we see lit?

Why does the Moon change shape?

The Sun lights half of the Moon. As the Moon orbits Earth, our viewing angle changes, so we see different amounts of its sunlit half. The Moon itself does not change shape.

Ordinary phases are not caused by Earth’s shadow. Earth’s shadow on the Moon is a lunar eclipse, which needs special alignment.

Watch the real Moon · words to know

Look for the Moon with a trusted adult over several evenings. Sketch what you see. It is not always visible at the same time or place in the sky.

Orbit: a path around another object. Waxing: the visible lit part grows. Waning: it shrinks. A quarter Moon is named for its place in the cycle; half its visible disc appears lit.

My discovery notebook

Save this view and an optional note on this device.

My note

No observations yet.

Quick quiz

Why do we see different Moon phases?

Simplified model: orbit and body sizes are not to scale. The Moon view uses a common Northern Hemisphere orientation; its angle varies by location and time. Phase cycle is approximately 29.5 days; actual timing varies.

Loading the fun.

THE BIG IDEA

What is happening?

The Sun lights half the Moon. As the Moon orbits Earth, we see different amounts of that sunlit half. The cycle takes about 29.5 days. Find new Moon, first quarter and full Moon, then follow the waning phases.

Simplified model: Idealised Northern Hemisphere orientation. Phase appearance rotates with viewing location; ordinary phases are not Earth's shadow.

Questions to explore

What will children learn?

Sequences eight Moon phases and distinguishes ordinary phases from a lunar eclipse.

How does it work?

The Sun lights half the Moon. As the Moon orbits Earth, we see different amounts of that sunlit half. The cycle takes about 29.5 days.

What should we try?

Find new Moon, first quarter and full Moon, then follow the waning phases.