diff --git a/libsgp4/DateTime.h b/libsgp4/DateTime.h
index 557011f..6d0d1c2 100644
--- a/libsgp4/DateTime.h
+++ b/libsgp4/DateTime.h
@@ -618,6 +618,16 @@ public:
         return Util::WrapTwoPI(Util::DegreesToRadians(theta / 240.0));
     }
 
+    /**
+     * Return the modified julian date since the j2000 epoch
+     * January 1, 2000, at 12:00 TT
+     * @returns the modified julian date
+     */
+    double ToJ2000() const
+    {
+        return ToJulian() - 2415020.0;
+    }
+
     /**
      * Convert to local mean sidereal time (GMST plus the observer's longitude)
      * @param[in] lon observers longitude
diff --git a/libsgp4/Globals.h b/libsgp4/Globals.h
index 0f7b2bc..d756832 100644
--- a/libsgp4/Globals.h
+++ b/libsgp4/Globals.h
@@ -70,14 +70,5 @@ const double kSECONDS_PER_DAY = 86400.0;
 const double kMINUTES_PER_DAY = 1440.0;
 const double kHOURS_PER_DAY = 24.0;
 
-// Jan 1.0 1900 = Jan 1 1900 00h UTC
-const double kEPOCH_JAN1_00H_1900 = 2415019.5;
-
-// Jan 1.5 1900 = Jan 1 1900 12h UTC
-const double kEPOCH_JAN1_12H_1900 = 2415020.0;
-
-// Jan 1.5 2000 = Jan 1 2000 12h UTC
-const double kEPOCH_JAN1_12H_2000 = 2451545.0;
-
 #endif
 
diff --git a/libsgp4/SGP4.cpp b/libsgp4/SGP4.cpp
index e8f0b50..fe92c80 100644
--- a/libsgp4/SGP4.cpp
+++ b/libsgp4/SGP4.cpp
@@ -672,7 +672,7 @@ void SGP4::DeepSpaceInitialise(
     /*
      * initialize lunar / solar terms
      */
-    const double jday = elements_.Epoch().ToJulian() - kEPOCH_JAN1_12H_2000;
+    const double jday = elements_.Epoch().ToJ2000();
 
     const double xnodce = 4.5236020 - 9.2422029e-4 * jday;
     const double xnodce_temp = fmod(xnodce, kTWOPI);
diff --git a/libsgp4/SolarPosition.cpp b/libsgp4/SolarPosition.cpp
index 11ae82e..1ddad9b 100644
--- a/libsgp4/SolarPosition.cpp
+++ b/libsgp4/SolarPosition.cpp
@@ -24,7 +24,7 @@
 
 Eci SolarPosition::FindPosition(const DateTime& dt)
 {
-    const double mjd = dt.ToJulian() - kEPOCH_JAN1_12H_1900;
+    const double mjd = dt.ToJ2000();
     const double year = 1900 + mjd / 365.25;
     const double T = (mjd + Delta_ET(year) / kSECONDS_PER_DAY) / 36525.0;
     const double M = Util::DegreesToRadians(Util::Wrap360(358.47583