I am greating an Array on UFO type (just a class i created)
When I try instantiate any. or all for that matter, of the elements in the array I get the following
error
An unhandled exception of type 'System.NullReferenceException' occurred in spaceInvaders.exe

Additional information: Object reference not set to an instance of an object.
and points to this line in th code
item.X = screen.Height / 2;

here is the code for that part

Code:
 public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        Viewport screen;


        //create background image
        Texture2D background;
        Rectangle mainFrame;

        UFO[] aliensArr = new UFO[5];
       
  protected override void Initialize()
        {
            screen = graphics.GraphicsDevice.Viewport;
           
            foreach (UFO item in aliensArr)
            {
                
                   item.X = screen.Height / 2;
                   item.Y = screen.Width / 2;
                   item.Width = 75.0f;
                   item.Height = 50.0f;
            }
            base.Initialize();
        }
......
}
and the UFO class is
Code:
class UFO
    {
        public Texture2D Visual { get; set; }
        public float X { get; set; }
        public float Y { get; set; }
        public float Width { get; set; }
        public float Height { get; set; }
        public Rectangle Rect
        {
            get
            {
                return new Rectangle((int)X, (int)Y, (int)Width, (int)Height);
            }

        }

    }
any ideas why i am getting this?