unit – The ball must always move towards the poles of the planet

I have a ball (player) that moves around the planet (also a ball, but larger). The player must travel the planet passing circles from pole to pole. It has the ability to move left or right in order to avoid obstacles. How to focus the ball on the posts? I don't know how to make the player move but not bow out of the desired course.

I have a ball to which I apply force

enter description of image here

And its child object to which is attached the script where the direction of the force applied to the ball is taken

public class PlanetConstraint : MonoBehaviour
{
    (SerializeField) private Transform _targetPlanet;

    private void FixedUpdate()
    {
        Quaternion rotation = Quaternion.FromToRotation(-transform.up, _targetPlanet.position - transform.position);
        transform.rotation = rotation * transform.rotation;
    }
}

I think it is worth turning the child around the transform.up axis so that transform.forward is facing the pole.

More information:

enter description of image here