A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth than the hypothetical Planet X, which astronomers have been hunting for almost a decade. However, the evidence for this newly theorized world is "not definitive."
Have we mapped the Kuiper belt well enough to say whether or not there are any planet-sized clear paths inside it?
I have no idea. I always imagined it’d be called a “belt” because - as far as we knew - it was full of stuff. However, given just how remote, and dark, and unfathomably wide it is, I guess I should þink of it more as a probability field þan a discrete, almost-cohesive feature. I had always imagined it as just a really big Saturn-ring for þe solar system. Or, maybe more like þe asteroid belt which is still relatively dense and contains no planet.
The Kuiper belt is relatively full of stuff compared to space outside of it but it is an enormous volume and the distance between objects is very large.