diff --git a/Environment/LayeredSphericalAtmosphereBuilder.h b/Environment/LayeredSphericalAtmosphereBuilder.h
index a9c32abc141c14490eb046b805cd0352ecb9e5af..f051485ca7de45460003628be03052a988995466 100644
--- a/Environment/LayeredSphericalAtmosphereBuilder.h
+++ b/Environment/LayeredSphericalAtmosphereBuilder.h
@@ -13,6 +13,7 @@
 #include <corsika/environment/NuclearComposition.h>
 #include <corsika/environment/VolumeTreeNode.h>
 #include <corsika/geometry/Point.h>
+#include <corsika/units/PhysicalConstants.h>
 #include <corsika/units/PhysicalUnits.h>
 
 #include <memory>
@@ -20,16 +21,6 @@
 
 namespace corsika::environment {
 
-  /**
-   * A namespace containing various Earth radii.
-   */
-  namespace EarthRadius {
-    static constexpr auto Mean{6'371'000 * units::si::meter};
-    static constexpr auto Eqautorial{6'378'137 * units::si::meter};
-    static constexpr auto Polar{6'356'752 * units::si::meter};
-    static constexpr auto PolarCurvature{6'399'593 * units::si::meter};
-  } // namespace EarthRadius
-
   class LayeredSphericalAtmosphereBuilder {
     std::unique_ptr<NuclearComposition> composition_;
     geometry::Point center_;
@@ -44,7 +35,7 @@ namespace corsika::environment {
   public:
     LayeredSphericalAtmosphereBuilder(
         corsika::geometry::Point center,
-        units::si::LengthType earthRadius = EarthRadius::Mean)
+        units::si::LengthType earthRadius = units::constants::EarthRadius::Mean)
         : center_(center)
         , earthRadius_(earthRadius) {}
 
diff --git a/Framework/Units/PhysicalConstants.h b/Framework/Units/PhysicalConstants.h
index eacccfe165b779f810156cdf3c4d30df35d99dba..da86bbd1edc3564badee1dedfd0bf7ead7d2ad4f 100644
--- a/Framework/Units/PhysicalConstants.h
+++ b/Framework/Units/PhysicalConstants.h
@@ -53,6 +53,16 @@ namespace corsika::units::constants {
   // molar gas constant
   auto constexpr R = Rep(8.314'459'8) * joule / (mole * kelvin);
 
+  /**
+   * A namespace containing various Earth radii.
+   */
+  namespace EarthRadius {
+    static constexpr auto Mean{6'371'000 * meter};
+    static constexpr auto Eqautorial{6'378'137 * meter};
+    static constexpr auto Polar{6'356'752 * meter};
+    static constexpr auto PolarCurvature{6'399'593 * meter};
+  } // namespace EarthRadius
+
   // etc.
 
 } // namespace corsika::units::constants