I Need help with gravity

I'm trying to make a fps game on a planet that goes around the sun, but when I run the script, the planet starts moving around the sun, but I get thrown off the planet.

I do have a script that's supposed to give the player gravity toward the planet, but it's not.

Can anyone help

This is the code I'm using for the gravity

 using UnityEngine;
 using System.Collections;
  
 public class GravityScript : MonoBehaviour {
     public Transform gravitySource;
     public float gravScalar = 4.0f;
     public Vector3 rotOffset = Vector3.zero;
     // Use this for initialization
     void Start () {
  
     }
  
     // Update is called once per frame
     void FixedUpdate () {
        var direction = gravitySource.position - transform.position;
        rigidbody.AddForce(direction.normalized * gravScalar);
        transform.rotation = Quaternion.LookRotation(direction.normalized) 
                         * Quaternion.Euler(rotOffset);
     }
 }