There are far more than the 6 starter planets in the universe.
This map is a general outline of the universe. Typically, starter planets are just so you can level up a bit and gather enough resources to warp to the next place and settle.There are a lot more PvP and PvE planets around the universe. Each structure you build on the starter planets will exist for 7 days before it’s wiped by the server, so you’ll want to goo elsewhere before that.