private bool obstacleCollisionDetection()
        {
            Point ballCenter = new Point(this.ballBoundingBox.X + ballRadius,
                this.ballBoundingBox.Y + ballRadius);

            Point sphereCenter1 = new Point(this.sphereBoundingBox1.X + sphereRadius1, 
                this.sphereBoundingBox1.Y + sphereRadius1); // create a coordinate center for scoring sphere 1 for collision detection 

            Point sphereCenter2 = new Point(this.sphereBoundingBox2.X + sphereRadius2,
                this.sphereBoundingBox2.Y + sphereRadius2); // create a coordinate center for scoring sphere 2 for collision detection

            // Note: There is a logic problem with this growing sphere, the shrinking one
            // is fine.
            // If the either of the colliding object is not destroyed upon collision, the
            // moving ball will get stuck within the sphere and will loop, infinitely
            // increasing its size. This should not be a problem for us as one of our balls is
            // destroyed upon contact but just to highlight the issue.
            Vector distanceVector2 = sphereCenter1 - ballCenter; // checks for collision for scoring sphere 1
            if (distanceVector2.Length < (ballRadius + sphereRadius1))
            {
                this.Children.Remove(scoringSphere1); // destroy original scoring sphere
                if (sphereRadius1 <= 75) // for winning game if a target size is reached
                {
                    sphereRadius1 += 5; // increase sphere size
                }
                makeScoringSphere1(sphereRadius1); // creates a bigger scoring sphere

                distanceVector2.Normalize();
                BallDirection = 2 * Vector.Multiply(-BallDirection, distanceVector2)
                    * distanceVector2 + BallDirection;
            }

            Vector distanceVector3 = sphereCenter2 - ballCenter; // checks for collision for scoring sphere 2
            if (distanceVector3.Length < (ballRadius + sphereRadius2))
            {
                distanceVector3.Normalize();
                BallDirection = 2 * Vector.Multiply(-BallDirection, distanceVector3)
                    * distanceVector3 + BallDirection;

                this.Children.Remove(scoringSphere2); // destroy original scoring sphere
                if (sphereRadius2 >= 25) // for losing game if a target size is reached
                {
                    sphereRadius2 -= 5; // decrease sphere size
                }
                makeScoringSphere2(sphereRadius2); // creates a smaller scoring sphere
            }

            int i = 0;
            foreach (Point obstacle in obstacleCenters)
            {
                Vector distanceVector = obstacle - ballCenter;
                if (distanceVector.Length < (ballRadius + obstacleRadius))
                {
                    // look at http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=30
                    // for a proper explanation on how to calculate the new direction vector
                    distanceVector.Normalize();
                    BallDirection = 2 * Vector.Multiply(-BallDirection,distanceVector)
                        * distanceVector + BallDirection;
                    
                    // delete obstacle
                    this.obstacleCenters.RemoveAt(i);
                    Ellipse ellipseToRemove = this.obstacles;
                    this.Children.Remove(ellipseToRemove);
                    this.obstacles.Remove(ellipseToRemove);

                    // rewind and play the sound
                    mp.Position = TimeSpan.FromMilliseconds(0);
                    mp.Play();
                    return true;
                }
                i++;
            }
            return false;
        }