javascript to C#, UnityEngine.Object to GameObject?

I am learning C# and unity, but im following a tutorial that is using javascript. I got stuck here:

 var newParticles = Instantiate(hitParticles, hit.point, Quaternion.FromToRotation(Vector3.up, hit.normal));
                     hitParticles.transform.position = hit.point;
                     hitParticles.transform.rotation = Quaternion.FromToRotation(Vector3.up, hit.normal);
                     hitParticles.Emit();
                     newParticles.GetComponent(ParticleAnimator).autodestruct = true;

I was reading the documents, Instantiate returns a UnityEngine.Object. So I tried UnityEngine.Object newParticles = Instantiate()... This gives me an error in the last statement because newParticles is not a GameObject, so I cant use GetComponent() with it. I looked up GetComponent, which returns a Component, and a Component is a child of UnityEngine.Object. Why do I have to cast newParticles as a GameObject first?

Here is what I did:

 GameObject newParticles = (GameObject)Instantiate(hitParticles, hit.point, Quaternion.FromToRotation(Vector3.up, hit.normal));
                 hitParticles.transform.position = hit.point;
                 hitParticles.transform.rotation = Quaternion.FromToRotation(Vector3.up, hit.normal);
                 hitParticles.Emit();
                 newParticles.GetComponent<ParticleAnimator>().autodestruct = true;