为什么在Unity中将对象更改为父对象时实例化的对象被销毁？

Question

我用行星创造了一个游戏。中心是一颗星星。从下面有一个我要运行的星球。之后，我在屏幕上单击，克隆对象被实例化并进入太阳轨道。行星得到父变换，sun.transform。这很好。但是，有时当行星得到父变换时，它会被销毁。

private void OnCollisionEnter2D(Collision2D other) {

    if (isFixed)
        return;

    if (other.transform.tag == "Sun") {

        rb.constraints = RigidbodyConstraints2D.FreezeAll;
        rb.bodyType = RigidbodyType2D.Static;
        transform.parent = Par;
        rb.gravityScale = 0;
        isFixed = true;
        source.PlayOneShot (Hit, 1);
        Game.Score += 1;
        Game.plusStage += 1;
        PlayerPrefs.SetInt ("Score", Game.Score); 
        PlayerPrefs.Save ();

        if (isHit == false) {
            rb.AddTorque (10, ForceMode2D.Impulse);
            rb.AddForce (new Vector2 (Random.Range(-1.0f, 1.0f), 10f));
            transform.parent = Par2;
            GameOver = true;
            showGm = true;
        }


    } else if (other.transform.tag == "Comet" || other.transform.tag == "Planet") {
        gameObject.transform.parent = Par2;
        rb.bodyType = RigidbodyType2D.Dynamic;
        Destroy(gameObject.GetComponent<CapsuleCollider2D>());
        gameObject.GetComponent<SpriteRenderer> ().sortingOrder = 3;
        isHit = false;
        rb.constraints = RigidbodyConstraints2D.None;
        gameObject.GetComponent<Rigidbody2D> ().constraints = RigidbodyConstraints2D.None;
        rb.gravityScale = 5;
        gameObject.GetComponent<CapsuleCollider2D> ().isTrigger = true;
        rb.AddTorque (10, ForceMode2D.Impulse);
        rb.AddForce (new Vector2 (Random.Range(-1.0f, 1.0f), 10f));
        GameOver = true;
        source.PlayOneShot (Nohit, 1);
        NoHit.Play ();
        showGm = true;
        if (vibro == 1) {
            Handheld.Vibrate();
        }
    } 

}