Moon Phases Simulator
Move the Moon around its orbit and see what phase looks like from Earth.
About the Moon Phases Simulator
Free moon phases simulation. Drag the Moon around Earth, see the view from Earth and the phase name, with waxing and waning, crescent and gibbous explained. Built for earth & space, the moon phases simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Move the Moon around its orbit and see what phase looks like from Earth. Use it to explore earth & space ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Moon Phases Simulator
- Use the controls to change Orbit angle. The simulation reacts instantly.
- Pick an option such as New, First quarter, Full, Third quarter to switch modes or load an example.
- Press "Animate" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Jump to Full Moon.
- Animate the whole month.
- Find the first quarter.
- Drag the Moon around.
Key ideas you can learn
- Half of the Moon is always lit by the Sun. What changes is how much of that lit half faces Earth.
- The full cycle takes about 29.5 days.
- Waxing means the lit part is growing, and waning means it is shrinking.
Where this is used in the real world
The Moon's phases guided calendars, tides and festivals throughout history, and astronomers, sailors and farmers still track them.
Who is this simulation for?
Astronomy and earth-science students, and teachers who need a visual model to explain what is happening in the sky.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Is the Moon's shadow from Earth causing the phases?
No. Phases come from our viewing angle of the sunlit half. Earth's shadow only falls on the Moon during a lunar eclipse.
What is the difference between a crescent and a gibbous Moon?
A crescent shows less than half of the disc lit, while a gibbous shows more than half.
Is the Moon Phases Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Moon Phases Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.