Explore the Moon Phases Simulator
Move the Moon around its orbit and see what phase looks like from Earth. Free, no signup, runs in your browser.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
See it in action
The Moon Phases Simulator with sample data entered and the result showing.
What is the Moon Phases Simulator?
Move the Moon around its orbit and see what phase looks like from Earth. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
The Moon's phases guided calendars, tides and festivals throughout history, and astronomers, sailors and farmers still track them.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
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.
Jump to Full Moon.
Animate the whole month.
Find the first quarter.
Used for
Pick one to see how it fits.
Earth & Space learners
Astronomy and earth-science students, and teachers who need a visual model to explain what is happening in the sky.
Try it freeTeachers
For teachers: project the Moon Phases Simulator on the board, let students predict the result, then run it together and test this: Animate the whole month. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
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. The Moon Phases Simulator is free, needs no signup or download and runs in your web browser. It is part of the Earth & Space group of AZRS simulations.
Does the Moon Phases Simulator work on a phone or tablet?
Yes. The Moon Phases Simulator takes touch input as well as mouse input, so you can use its 1 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Moon Phases Simulator?
1. In the Moon Phases Simulator, use the controls to change Orbit angle. The simulation reacts instantly. 2. In the Moon Phases Simulator, pick an option such as New, First quarter, Full, Third quarter to switch modes or load an example. 3. In the Moon Phases Simulator, press "Animate", "Today's real Moon" to start, reset or change what is happening. 4. Start with this experiment: Jump to Full Moon. Drag any glowing handle, object or slider with your mouse or finger and the Moon Phases Simulator responds in real time. 5. Change one setting at a time and watch which readout moves, then compare it with this idea: Half of the Moon is always lit by the Sun. What changes is how much of that lit half faces Earth.
More free tools
Related to the Moon Phases Simulator.
Try the Moon Phases Simulator now
Move the Moon around its orbit and see what phase looks like from Earth. Free to use.
Try it free