onClipEvent(enterFrame) {
if(this._x<=0) this._x=2; //0 is the left boundary for my invader, you may want to change your's
if(this._x>=580) this._x=478; //480 is the right boundary, feel free to change!
if(this._x>80 && this._x<480) { //just to make sure that the ship is in a valid position
if (Key.isDown (Key.RIGHT) ) { //right key is down
this._x+=5 //5 is the speed, this moves the clip 5 to the right
}
else if (Key.isDown (Key.LEFT) ) {
this._x-=5 // moves the clip 5 to the left
}

if(Key.isDown (Key.SPACE) ) { //space key is down

if(_root.bullet._y>600) { //checks to see if the bullet is off the screen (so you can fire again)
bullet._x=this._x //sets the bullet's x to your x

bullet._y=this._y //sets the bullet's y to your y

}
}
} //end the onClipEvent handler

onClipEvent(enterFrame) {

this._y+=10 //moves the bullet 10 up

}

onClipEvent(load) {
this._y=-100-random(500) //sets the ships y to a random position (-100 -> -600)
this._x=random(600) //sets the ships x to a random position (0 -> 600)
}
onClipEvent(enterFrame) {
if(this._y<=0) { //if this is below the y border
_root.health-=10; //subtract 10 from the health
}
this._y+=3 //moves the ship by 3
if (this.hitTest(_root.bullet)) { //if this gets hit by the bullet
_root.score+=10 //increase the score by 10
//you could make the ship go to it's explode animation if you had one
this._y=-100-random(500) //sets the y random
this._x=random(600)//sets the x random
}

if(_root.health<=0) {

_root.gotoAndStop(3)

}
}