Update uxarray/grid/grid.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: philipc2

uxarray/grid/grid.py

@@ -1907,7 +1907,7 @@ def compute_face_areas(
             # Ω_pix = 4π / (12 * Nside²) = π / (3 * Nside²)
             # Górski et al. 2005, “HEALPix: A Framework for High‐Resolution Discretization and Fast Analysis of Data Distributed on the Sphere”
             n_side = self._ds.attrs["n_side"]
-            face_area = np.pi / 3 * n_side**2
+            face_area = np.pi / (3 * n_side**2)
             return np.ones(self.n_face) * face_area, None
 
         self.normalize_cartesian_coordinates()