diff --git a/src/core/modules/Planet.cpp b/src/core/modules/Planet.cpp
index b4fb68ff24c6c..e387041e7a47f 100644
--- a/src/core/modules/Planet.cpp
+++ b/src/core/modules/Planet.cpp
@@ -2865,7 +2865,7 @@ float Planet::getVMagnitude(const StelCore* core) const
 double Planet::getAngularRadius(const StelCore* core) const
 {
 	const double rad = (rings ? rings->getSize() : equatorialRadius);
-	return std::atan2(rad*sphereScale,getJ2000EquatorialPos(core).norm()) * M_180_PI;
+	return std::asin(rad*sphereScale/getJ2000EquatorialPos(core).norm()) * M_180_PI;
 }
 
 
diff --git a/src/core/modules/StarMgr.cpp b/src/core/modules/StarMgr.cpp
index 1798135abcb9e..ff5fef45f7ccd 100644
--- a/src/core/modules/StarMgr.cpp
+++ b/src/core/modules/StarMgr.cpp
@@ -1319,10 +1319,10 @@ void StarMgr::draw(StelCore* core)
 	PlanetP moon = GETSTELMODULE(SolarSystem)->getMoon();
 	Vec3d moonPos=moon->getJ2000EquatorialPos(core);
 	const double moonRadius = moon->getEquatorialRadius() * moon->getSphereScale();
-	double angularSize = atan2(moonRadius, moonPos.norm());
+	double angularSize = asin(moonRadius / moonPos.norm());
 	moonPos.normalize();
 	SphericalCap moonCap(moonPos, cos(angularSize));
-	for (auto  cap : viewportCaps)
+	for (auto  &cap : viewportCaps)
 	{
 	    if (cap.intersects(moonCap))
 		filterMoon=true;