In our Solar System, highly unlikely. The only "possible" place a planet could lurk is beyond the Kuiper Belt. It has been hypothesised, but so far nothing has been seen. This does not discount that there "may" be another planet out there, it just hasn't been observed.
Computer simulations propose that an Earth sized planet "could" exist beyond the Kuiper belt as it would explain the Kuiper cliff.
14
We have no idea. :() We might discover some in the future. Maybe not. No one knows the future.
Kepler discovered the orbits of the solar system are elliptical.
New planets are more or less constantly being discovered outside the Solar system. There are almost certainly no unknown planets still lurking within the Solar system, though.
9 P in the S S = 9 Planets in the Solar System
Our solar system is the planets
There are nine planets in the solar system
Extra solar planets are planets that is outside of our solar system.
There are eight planets and five dwarf planets in our solar system.
There are 5 rocky planets in our solar system if you count Pluto. If not, there are 4 rocky planets in the solar system.
Planets that are not part of our solar system and in other solace systems are called exo-solar planets or exoplanets.
Name the planets that do not exist in the solar system