a problem on explosion on the official tutorial space shooter

I’m new to Unity.Following the tutorials of space shooter,i came across a problem on explosion, After hitting the asteroid, the spaceship,along with the asteroid disappears,leaving a strange image on the game scene.I suspect that it is from the images of player’s engine.I wonder if someone could offer me the answer.thX!!!

code:
public class DestroyByCollision : MonoBehaviour {
public GameObject explosion;
public GameObject playerExplosion;

void OnTriggerEnter(Collider other)
{

    if(other.tag=="Boundary")
    {
        return;
    }
    Instantiate(explosion, transform.position, transform.rotation);
    if (other.tag=="Player")
    {
        Instantiate(playerExplosion, other.transform.position, other.transform.rotation);
        Destroy(playerExplosion);
    }
    Destroy(gameObject);
    Destroy(other.gameObject);

}

}

the problem picture after collison:
[87187-qq截图20170202231335.png|87187]

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