I'll write more about this later when I have time, but apparently the Planet-9-that's-not-really-Planet-9 theory article just came out and I'm quoted a bunch: https://physicsworld.com/a/earth-sized-planet-could-be-lurking-at-the-edge-of-the-solar-system-simulations-suggests/ 

 @e38e83a6 👍 very cool