protected override void OnRender(DrawingContext context)
        {
            base.OnRender(context);

            if (!_load && Planets.Count > 0)
            {
                _aspects = new Dictionary<PlanetModel, List<AspectUI>>();
                for (int i = 0; i < Planets.Count; i++)
                {
                    List<AspectUI> list = new List<AspectUI>();
                    for (int j = 0; j < Planets.Count; j++)
                    {
                        var aspect = new AspectUI(Planets[j]);
                        list.Add(aspect);
                        this.Children.Add(aspect);
                    }
                    _aspects.Add(Planets[i], list);
                }
                _load = true;
            }
        }

public class AspectUI : Canvas
{
    PlanetModel _planet;
    bool _show;
    Point _startPoint;
    Point _endPoint;
    Pen _pen;
    private static Action EmptyDelegate = delegate() { };

    public bool ShowAspect { get { return _show; } set { _show = value; } }

    public AspectUI(PlanetModel planet)
    {
        _planet = planet;
    }

    public void Show(Point startPoint, Point endPoint, Pen pen)
    {
        _startPoint = startPoint;
        _endPoint = endPoint;
        _pen = pen;
        //this.Dispatcher.Invoke(DispatcherPriority.Render, EmptyDelegate);
    }

    protected override void OnRender(DrawingContext context)
    {
        base.OnRender(context);

        if (_show)
                context.DrawLine(_pen, _startPoint, _endPoint);
    }
}

   public List<PlanetModel> Planets
   public OrbModel Orbs

                            <local:PlanetCircle Panel.ZIndex="2" 
                                                Radius="{Binding Path=Radius, Converter={StaticResource SizeConverter2}}" 
                                                Planets="{Binding Path=Planets}" 
                                                Orbs="{Binding Path=Orbs}" 
                                                CentreX="{Binding Path=Radius}" 
                                                CentreY="{Binding Path=Radius}" 
                                                Rotation="{Binding ElementName=icPlanets, Path=DataContext.Angle}">
                            </local:PlanetCircle>