There may be an undiscovered planet in the outer solar system whose presence is revealed by the strange orbit of objects beyond the eighth planet Neptune. The tantalizing prospect of a ninth ...

No one was able to observe the planet directly ... James Unwin: If we do do our searches and it turns out that there is a planet in the outer solar system, this would be an absolutely incredible ...

Brown is still busy investigating the outer solar system ... you admit the possibility of a Planet 9, and you think about how Planet 9 got there, there’s no reason to not start asking the ...