exoplanets are often smaller than pluto. It's got nothing to do with size. Pluto doesnt control its orbit, there are other bits in its orbit that havent been cleared so its not a planet yet.
we can tell there is a planetoid bigger than pluto further out based on the math of gravity saying there is a pull coming from that point without even seeing it. thats how we found pluto too. Some smart folk noticed wobbles in neptunes orbit and did some heckin math to figure out "hey something is fucking with neptune's orbit roughly of X mass."
We also have a few probes taking pictures of a lot of stuff. All those high res pictures of pluto arent renders of an idea, they are real pictures from a camera on a probe.
also just google the kuiper belt. Pluto just happens to be the biggest object in a massive belt of object on the edge of the system. It's the same as calling for the planet status of the biggest asteroid in the belt between Jupiter and mars.
We also have a few probes taking pictures of a lot of stuff. All those high res pictures of pluto arent renders of an idea, they are real pictures from a camera on a probe.
also just google the kuiper belt. Pluto just happens to be the biggest object in a massive belt of object on the edge of the system. It's the same as calling for the planet status of the biggest asteroid in the belt between Jupiter and mars.