Eliminating redefined constant

Author: benguild

s2/s2_test.go

@@ -22,6 +22,7 @@ import (
 	"math/rand"
 	"os"
 
+	"github.com/golang/geo/earth"
 	"github.com/golang/geo/r1"
 	"github.com/golang/geo/r2"
 	"github.com/golang/geo/s1"
@@ -74,8 +75,7 @@ func float64Near(x, y, ε float64) bool {
 	return math.Abs(x-y) <= ε
 }
 
-// The Earth's mean radius in kilometers (according to NASA).
-const earthRadiusKm = 6371.01
+var earthRadiusKm = earth.Radius.Kilometers()
 
 // kmToAngle converts a distance on the Earth's surface to an angle.
 func kmToAngle(km float64) s1.Angle {