Planet 9, still invisible in every telescope pointed its way, survives as a hypothesis because the orbital math keeps pointing back to an unseen mass. I see a pattern that has become harder to dismiss ...

Planet 9 sits at the edge of scientific imagination, promising either an epic expansion of the Solar System or a lesson in how easily patterns can mislead us. As new data arrive and old assumptions ...

Mike Brown is convinced that beyond Neptune, at the far reaches of our solar system, there's an unseen giant planet. "This is the 5th largest planet in our solar system, lurking out there, waiting to ...