CesiumGS · mzschwartz5 · Aug 22, 2025 · Aug 22, 2025 · Aug 22, 2025 · Aug 27, 2025
diff --git a/Apps/SampleData/Mars.czml b/Apps/SampleData/Mars.czml
diff --git a/Apps/SampleData/MarsPointsOfInterest.geojson b/Apps/SampleData/MarsPointsOfInterest.geojson
diff --git a/Apps/SampleData/models/Mars/Curiosity.glb b/Apps/SampleData/models/Mars/Curiosity.glb
diff --git a/Apps/SampleData/models/Mars/Ingenuity.glb b/Apps/SampleData/models/Mars/Ingenuity.glb
diff --git a/Apps/SampleData/models/Mars/Perseverance.glb b/Apps/SampleData/models/Mars/Perseverance.glb
diff --git a/Apps/Sandcastle/gallery/Mars.html b/Apps/Sandcastle/gallery/Mars.html
diff --git a/Apps/Sandcastle/gallery/Mars.jpg b/Apps/Sandcastle/gallery/Mars.jpg
diff --git a/CHANGES.md b/CHANGES.md
@@ -21,6 +21,7 @@
 
 - Added support for the [EXT_mesh_primitive_restart](https://github.com/KhronosGroup/glTF/pull/2478) glTF extension. [#12764](https://github.com/CesiumGS/cesium/issues/12764)
 - Added spherical harmonics support for Gaussian splats. Currently supported with the SPZ compression format.
+- Added `Ellipsoid.MARS` for use with Mars terrain and imagery. [#12828](https://github.com/CesiumGS/cesium/pull/12828)
 
 #### Deprecated :hourglass_flowing_sand:
 

diff --git a/packages/engine/Source/Core/Ellipsoid.js b/packages/engine/Source/Core/Ellipsoid.js
@@ -254,6 +254,15 @@ Ellipsoid.MOON = Object.freeze(
   ),
 );
 
+/**
+ * An Ellipsoid instance initialized to a sphere with the mean radii of Mars.
+ * Source: https://epsg.io/104905
+ *
+ * @type {Ellipsoid}
+ * @constant
+ */
+Ellipsoid.MARS = Object.freeze(new Ellipsoid(3396190.0, 3396190.0, 3376200.0));
+
 Ellipsoid._default = Ellipsoid.WGS84;
 Object.defineProperties(Ellipsoid, {
   /**