Written in the dust

Crater Moon

Every impact leaves a mark.
Give this little Moon a history.

Impactor diameter 130 m Impact speed 18 km/s Angle above the ground 65°

10° · grazing90° · vertical

Click anywhere on the surface to launch. Drag to orbit. The pale ring previews the crater’s approximate rim.

Your impacts0

Latest crater—

Try a small impact across the rim of an older crater.

Starting surface & seed

Starting surface

Restart repeats the starting surface. Your impact sequence makes its own history.

Illustrative crater shapes and relative sizes. Terrain scale, flight time and ejecta motion are simplified.

Click the surface to launch an impactor

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Crater Moon

Reshape a little moon with incoming rocks. Dig craters, scatter ejecta, and watch each new impact leave its mark on the landscape.

Overlapping impact craters and pale ejecta across a rocky lunar landscape against dark space.

Enable JavaScript in a browser with WebGL 2 to run this interactive simulation.

An impact can change a moon in an instant. Watch incoming rocks dig bowls, raise rims and throw material across the surface.

The hollow left by an impact is a crater. Material thrown out of it is called ejecta.
Larger or faster impactors make larger craters here. A shallow impact spreads the ejecta unevenly.
New impacts reshape older craters. The surface keeps a record of the impacts you make.
This is an illustrative patch of lunar ground. Impact sizes and times are simplified so you can explore the patterns.

Try this: Make a small crater, then aim a larger impact beside it. Look at how the new rim and ejecta change the older crater.