The problem lays in the fact that it MUST cause gravitational effects. That is how the universe works.Alisbet said:Behind the sun, at the opposite side of earth's orbit. And let's assume that this planet in question is about the same size as Earth and does not cause any noticeable gravitational effects.ReadyAmyFire said:Don't know what's in where? In the sun? Behind the sun?
I think something that massive would be noticed by its gravitational effects. Was it Neptune or Pluto which was found specifically by following an unknown source of gravity?
inb4 jokes about the size or Ur(my)anus.
If you want to talk about an entirely hypothetical "what-if" just as a thought experiment, sure, why not. We would mount missions and send probes and have raving mad parties about how we were going to settle this other planet. If it has similar composition to earth we could speculate on how it would help our over-population problems. The discovery would fuel massive interest in our space program. It would be awesome.
But it cannot exist in reality, if it did, we would know about it, because there is no way that a) a stable, non-colliding orbit could be maintained or b) the planet's gravitational effects could be missed.