diff --git a/scenes/Main.tscn b/scenes/Main.tscn
index 990a849..a269a98 100644
--- a/scenes/Main.tscn
+++ b/scenes/Main.tscn
@@ -1,19 +1,15 @@
-[gd_scene load_steps=4 format=2]
+[gd_scene load_steps=3 format=2]
 
-[ext_resource path="res://scenes/Train.tscn" type="PackedScene" id=1]
-[ext_resource path="res://scenes/Railway.tscn" type="PackedScene" id=2]
 [ext_resource path="res://scenes/OrbitCamera.tscn" type="PackedScene" id=3]
+[ext_resource path="res://scenes/OrbitSystem.tscn" type="PackedScene" id=4]
 
 [node name="Main" type="Node2D"]
 
 [node name="DirectionalLight" type="DirectionalLight" parent="."]
 transform = Transform( 0.515898, 0.606099, -0.605386, -0.393123, 0.795389, 0.461314, 0.76112, -2.26831e-08, 0.648611, 0, 0, 0 )
+visible = false
 
-[node name="OrbitCamera" parent="." instance=ExtResource( 3 )]
+[node name="Camera" parent="." instance=ExtResource( 3 )]
 _speed = 0.5
 
-[node name="Railway" parent="." instance=ExtResource( 2 )]
-
-[node name="Train" parent="." instance=ExtResource( 1 )]
-_speed = 5.0
-_railwayPath = NodePath("../Railway")
+[node name="Orbit System" parent="." instance=ExtResource( 4 )]
diff --git a/scripts/orbits/Orbit.cs b/scripts/orbits/Orbit.cs
new file mode 100644
index 0000000..0aca13e
--- /dev/null
+++ b/scripts/orbits/Orbit.cs
@@ -0,0 +1,12 @@
+using Godot;
+using System;
+
+public class Orbit
+{
+    public Orbit(PointMass a, PointMass b)
+    {
+
+    }
+
+    // ellipse
+}
diff --git a/scripts/orbits/OrbitSystem.cs b/scripts/orbits/OrbitSystem.cs
index 358ad53..12e2531 100644
--- a/scripts/orbits/OrbitSystem.cs
+++ b/scripts/orbits/OrbitSystem.cs
@@ -26,7 +26,9 @@ public class OrbitSystem : Node, IMassive, ILocation
 
     public float Mass { get; } = 1;
 
-    private ImmediateGeometry _orbit;
+    private Orbit _orbit;
+
+    private ImmediateGeometry _orbitGeometry;
 
     public override void _Ready()
     {
@@ -39,35 +41,40 @@ public class OrbitSystem : Node, IMassive, ILocation
         DrawOrbit();
     }
 
+    private void InitOrbit()
+    {
+
+    }
+
     private void DrawOrbit()
     {
         int steps = 100;
 
-        _orbit.Clear();
-        _orbit.Begin(Mesh.PrimitiveType.LineLoop);
-        _orbit.SetColor(new Color(1, 0, 0));
+        _orbitGeometry.Clear();
+        _orbitGeometry.Begin(Mesh.PrimitiveType.LineLoop);
+        _orbitGeometry.SetColor(new Color(1, 0, 0));
         for (int i = 0; i < steps; i++)
         {
             float t = i / (float)steps;
             float a = t * Mathf.Tau;
 
-            _orbit.AddVertex(new Vector3
+            _orbitGeometry.AddVertex(new Vector3
             {
                 x = Mathf.Sin(a),
                 z = Mathf.Cos(a)
             });
         }
-        _orbit.End();
+        _orbitGeometry.End();
     }
 
     private void InitGeometry()
     {
-        _orbit = new ImmediateGeometry();
+        _orbitGeometry = new ImmediateGeometry();
         var m = new SpatialMaterial();
         m.VertexColorUseAsAlbedo = true;
         m.FlagsUnshaded = true;
-        _orbit.MaterialOverride = m;
-        AddChild(_orbit);
+        _orbitGeometry.MaterialOverride = m;
+        AddChild(_orbitGeometry);
     }
 
     private void InitPointMasses()
diff --git a/scripts/orbits/Planet.cs b/scripts/orbits/Planet.cs
index c93a33a..877455f 100644
--- a/scripts/orbits/Planet.cs
+++ b/scripts/orbits/Planet.cs
@@ -1,7 +1,7 @@
 using Godot;
 using System;
 
-public class Planet : Node
+public class Planet : Node, IMassive
 {
     [Export]
     public float Mass { get; set; }
diff --git a/scripts/orbits/PointMass.cs b/scripts/orbits/PointMass.cs
index bb277c1..bbeaa14 100644
--- a/scripts/orbits/PointMass.cs
+++ b/scripts/orbits/PointMass.cs
@@ -1,6 +1,6 @@
 using Godot;
 
-struct PointMass : IMassive, ILocation
+public struct PointMass : IMassive, ILocation
 {
     public float Mass => _massive == null ? _mass : _massive.Mass;
     public Vector3 Position => _spatial.Translation;
diff --git a/scripts/orbits/math/Double2.cs b/scripts/orbits/math/Double2.cs
new file mode 100644
index 0000000..942f746
--- /dev/null
+++ b/scripts/orbits/math/Double2.cs
@@ -0,0 +1,8 @@
+using Godot;
+using System;
+
+public struct Double2
+{
+    public double x;
+    public double y;
+}
\ No newline at end of file
diff --git a/scripts/orbits/math/Ellipse.cs b/scripts/orbits/math/Ellipse.cs
new file mode 100644
index 0000000..64751e7
--- /dev/null
+++ b/scripts/orbits/math/Ellipse.cs
@@ -0,0 +1,34 @@
+using Godot;
+using System;
+
+public struct Ellipse
+{
+    public double a { get => SemiMajorAxis; set => SemiMajorAxis = value; }
+    public double SemiMajorAxis { get; set; }
+
+    public double e { get => Eccentricity; set => Eccentricity = value; }
+    public double Eccentricity { get; set; }
+
+    public double b => SemiMajorAxis;
+    public double SemiMinorAxis => Math.Sqrt(Apisides.max * Apisides.min);
+
+    private Apisides Apisides => new Apisides(a, e);
+
+    public Ellipse(double a = 1, double e = 0)
+    {
+        SemiMajorAxis = a;
+        Eccentricity = e;
+    }
+}
+
+public struct Apisides
+{
+    public readonly double min;
+    public readonly double max;
+
+    public Apisides(double a, double e)
+    {
+        min = a * (1 - e);
+        max = a * (1 + e);
+    }
+}
\ No newline at end of file