Them seem to suffer some sort of Venus envy.......
From the article “...In their analysis, they estimate that Planet Nine has a mass of 6.2 times that of the Earth and a periphelion (the point at which it is closest to the sun) of around 300 AU.
It also has an inclination - how much it tilts compared to the solar system’s plane - of around 16 degrees.
By contrast, the Earth has an inclination of 0 degrees, while Pluto’s inclination is 17 degrees, according to EarthSky.org.....”
Planet Nine is way bigger than Earth or Pluto.