Animate Sprite Vertically

I am having real trouble getting a sprite to spawn on the screen at the top and then animate it from the top to the bottom. I have been following Ray Wenderlich’s tutorial on creating a simple game however that moves the sprite from right to left, I would like it to move from top to bottom and now I’m tremendously stuck! Below is my current code:

Code:

- (void)addComet:(CCTime)dt
{
    // Make sprite
    CCSprite *comet = [CCSprite spriteWithImageNamed:@"PlayerSprite.png"];
    
    // Verticle spawn range
    int minY = comet.contentSize.width;
    int maxY = self.contentSize.height - comet.contentSize.height / 2;
    int rangeY = maxY - minY;
    int randomY = (arc4random() % rangeY) + minY;
    
    // Position comets slightly off the screen
    comet.position = CGPointMake(self.contentSize.width + comet.contentSize.width, randomY);
    [self addChild:comet];
    
    // Duration range comets take to fly across screen
    int minDuration = 2.0;
    int maxDuration = 4.0;
    int rangeDuration = maxDuration - minDuration;
    int randomDuration = (arc4random() % rangeDuration) + minDuration;
    
    // Give comet animation
    CCAction *actionMove = [CCActionMoveTo actionWithDuration:randomDuration position:CGPointMake(0, 500)];
    CCAction *actionRemove = [CCActionRemove action];
    [comet runAction:[CCActionSequence actionWithArray:@[actionMove,actionRemove]]];
}

If anyone could point me in the right direction because I’ve been stuck on this for quite a while and just cannot get the sprite to spawn randomly at the top of the screen and then animate down to the bottom. I have also looked at sample code such as tweejump but have had no luck.