Array - 'transform' is not member of Object

it gives me an error 'transform' is not member of Object. How do I tell unity that the objects I put in the array , are GameObjects.

  #pragma strict

  var MaxPlanets:int = 10;

  var clonePlanet : GameObject;

  var PlanetMaterial : Material;

  var planetGroundMaps : Texture[];

  var planets:Array = new Array();

  function Start () {

  createPlanets();

  }

  function Update () {

  rotatePlanets();

  }

  function createPlanets():void{

  var radiusMax:float = 5;

  var radiusMin:float = 1;

  var radiusRan:float;

  var Angle:float;

  var planetPosition:Vector3 = new Vector3(0,0,0);

  var planetRotation:float;

  var RanTexture:int;

      for(var i:int = 0;i <= MaxPlanets;i++){

          radiusRan = Random.Range(radiusMin,radiusMax);;

          Angle = ((360 / MaxPlanets) * i) * (Mathf.PI/180);

          planetPosition.x = Mathf.Cos(Angle) * radiusRan;

          planetPosition.z = Mathf.Sin(Angle) * radiusRan;

          var newPlanet = Instantiate(clonePlanet,planetPosition,Quaternion.identity);

          RanTexture = Random.Range(0,4);

          newPlanet.renderer.material = PlanetMaterial;

          newPlanet.renderer.material.SetTexture("_PlanetGround",planetGroundMaps[RanTexture]);

           if(RanTexture<3){

           newPlanet.renderer.material.SetTexture("_Clouds",null);

           newPlanet.renderer.material.SetTexture("_HeightMap",null);

           newPlanet.renderer.material.SetTexture("_lights",null);

          planets.Add(newPlanet.gameObject );

           }

      }

  }

  function rotatePlanets():void{

      for (var i in planets){

          i.transform.RotateAround(Vector3.zero,Vector3.up,Time.deltaTime);

      }

  }