Those are just the 700+ confirmed planets. There are more undiscovered planets out there than there are fictional ones.
Hell, Kepler has only been looking at a small slice of sky, we literally are just beginning because we've barely scratched the vast variety of worlds out there.
Given that the human empire (and emperor) in the Dune universe was called the emperor of a thousand worlds (or was it a million? I forget), so, such a vast array of planets is fitting.
It also looks like one of those color blindness test things.