We Never Know
No Slack
Seems that you do not have much interest in Astronomy.
That is only a matter of convention of what can be termed as a planet (IAU definition of planet - Wikipedia). Actually, we have millions of asteroids* (largest, Ceres, with a diameter of 1,000 km), Centaurs (largest, Chariklo, with a diameter of 250 km) and comets, which revolve around the sun.
* "The asteroid belt contains tens of thousands, possibly millions, of objects over one kilometre in diameter." Solar System - Wikipedia
Asteroid Belt, Ceres, Kuiper Belt.
Nor do you.
Planet Nine is a hypothetical planet in the outer region of the Solar System. Its gravitational effects could explain the unusual clustering of orbits for a group of extreme trans-Neptunian objects (eTNOs), bodies beyond Neptune that orbit the Sun at distances averaging more than 250 times that of the Earth.
In Depth | Hypothetical Planet X – NASA Solar System Exploration