"We believe that continuing such activities will further expand our horizon in the field of planetary science." ...

The celestial body's unusual orbit “implies that something extraordinary occurred" in the early days of the solar system—and ...

A stronomers have discovered an incredibly rare non-planetary body lurking on the outer reaches of the Solar System, which ...

Planet Nine should appear stationary over the course of a single day but show detectable movement over months.

If Planet Nine is finally discovered, as one of those who first postulated its existence, does Brown have any suggestions for a possible formal name for this new member of the solar system?

A new study's "treasure map" suggests that a planet several times more massive than Earth could be hiding in our solar system, camouflaged by the bright strip of stars that make up the Milky Way.

Planet Nine? 'Extreme' objects hint at more evidence of possible unseen world When will we find Planet Nine? Learn more by listening to the episode "Does Planet Nine Exist?" ...

In contrast, Planet Nine could be anywhere in its orbit, perhaps as much as 70 billion miles away. If that’s the case, it might take a very long time before we’re able to discover Planet Nine.

Evidence of a ninth planet at the edge of the solar system was announced by Caltech researchers three years ago.

Why has it been so difficult so far to find Planet Nine, or whatever it might actually be? “Planet Nine is so faint that in order to even hope to detect it, everything has to go right ...

Even if Planet Nine never turns up, a search party at the edges of the solar system is a worthwhile endeavor, says Laughlin.

Planet Nine’s gravitational influence could even serve as a solution to the long-standing mystery of why the sun’s axis of spin is tilted six degrees askew to the orbits of the inner planets.