Constructor for a sky box object used to provide background imagery for the full scene whatever the camera rotation. Each parameter defines a material that maps on to the box to create impresssion of sky, floor and 360 degree horizon.

starfield skybox  based on V2.1 

/**
 * create a random starfield skybox
 */

import away3d.materials.TransformBitmapMaterial;
import away3d.primitives.Skybox;
import flash.display.BitmapData;
import flash.display.Sprite;

// create a temporary container-sprite to add stars into
var mc:Sprite = new Sprite();
        mc.graphics.beginFill(0);
        mc.graphics.drawRect(0,0,2048,2048);
        mc.graphics.endFill();
// add 2000 star-sprites to the container
var s:Sprite, r:Number;
for( var i:uint=0; i<2000; i++ ) {
        r = Math.random()*Math.random();
        s = new Sprite();
        s.graphics.beginFill(0xFFFFFF,0.9);
        s.graphics.drawCircle(0,0,r);
        s.graphics.endFill();
        s.x = r + (mc.width - 2*r)*Math.random();
        s.y = r + (mc.height - 2*r)*Math.random();
        mc.addChild(s);
}

// render the container-sprite to a bitmap
var bmd:BitmapData = new BitmapData(mc.width, mc.height, false, 0);
        bmd.draw(mc);
// create a 2x2 tiled material from the bitmap
var mat:TransformBitmapMaterial = new TransformBitmapMaterial(bmd, {
        smooth: true, precision:0,
        repeat: true, scaleX: 0.5, scaleY: 0.5 });
// create a skybox using that material on all 6 sides
var box:Skybox = new Skybox( mat,mat,mat,mat,mat,mat );
// and finally add it to the scene
scene.addChild(box);

Source Files : http://kishalmi.servus.at/flash/earth/

random runtime generated starfield-skybox