Threeworld is the third planet in Rocky’s home system. At least, Threeworld is what I call it. The Eridians don’t have a name for it, even in their own language. Just a designation: “Planet Three.” They didn’t have ancient people looking up at astronomical bodies and naming them after gods. They only discovered other planets in their system a few hundred years ago. But I don’t want to say “Planet Three” all the time, so I’ve named it Threeworld.
