What aren't you understanding? Of course I don't seriously believe aliens move objects around the solar system. It's just a silly thought experiment. The point

What aren't you understanding? Of course I don't seriously believe aliens move objects around the solar system. It's just a silly thought experiment. The point is it seems absurd that the past history of an object should matter, for this definition. Like if it's a big round object orbiting a star, it's a planet. It shouldn't matter how it got there. It seems quite possible there could be cases where another object clears the orbit of another object. Perhaps not aliens, but a rogue planet. I was trying to recreate the "star trek test" argument that I heard a real astronomer use. He was upset with the new definition, and made an analogy to start trek. On the show they don't wait around for 12 months to observe the planet and any objects in its orbit, let alone it's past history. He argued that any sensible definition should be possible to determine immediately. Of course we are arguing about the definition of a word, and all arguments are subjective and appeal to intuition. But still there can be bad definitions.