What is the name of the art style with wacky space alien characters? I've seen the style in many places over time but a good example which I can provide is the illustrations in the [Area 51](http://area51.stackexchange.com/) StackExchange site. Here are some examples:

![UFO and moon](https://i.stack.imgur.com/PKlNk.png)  

![Planet landscape with space vehicles](https://i.stack.imgur.com/XEgMA.png)  

![Aliens saying bye to a departing rocket ship](https://i.stack.imgur.com/Ab99Z.png)