Is Planet Nine lurking in the solar system?

Scientists have been on the hunt for a possible ninth planet in our solar system for some time. The existence of this elusive “Planet Nine” has sparked considerable debate, with arguments both for and against it.

Recent data suggests a strong likelihood that an undiscovered ninth planet may indeed be present. Unusual gravitational effects and strange orbital patterns observed in the Kuiper Belt have intensified speculation. NASA is developing a new telescope, expected to be operational by late 2025, designed to survey the entire night sky and potentially confirm Planet Nine’s existence.

A recent study offered the most compelling evidence yet for Planet Nine, suggesting it may be hidden within the Kuiper Belt. Researchers believe this mysterious planet is smaller than previously thought, with a mass between 1.5 and 3 times that of Earth. Its composition remains uncertain—it could be a rocky, icy body similar to Earth or something akin to a “super-Pluto.”

The planet’s significant mass suggests it might generate enough internal heat to sustain subsurface oceans. Associate professor Patryk Sofia Lykawka from Japan’s Kindai University, co-author of the study, noted that Planet Nine’s orbit would be highly inclined and situated far beyond Neptune.

The search for Planet Nine began in earnest in 2014 when scientists Konstantin Batygin and Michael Brown proposed that a previously unknown planet larger than Earth might exist in the far reaches of the solar system. They speculated that this “super-Earth,” with a mass five to seven times that of our planet, could be influencing the orbits of distant objects in the Kuiper Belt.

Astronomers have long noticed that some trans-Neptunian objects exhibit unusual, clustered orbits, hinting at an unseen gravitational influence. Prior to Batygin and Brown’s proposal, astronomers Scott Sheppard and Chadwick Trujillo observed similar anomalies in trans-Neptunian object orbits, suggesting that a hidden planet might be at work.

Batygin pointed out that since Neptune’s discovery in 1846, at least 30 astronomers have hypothesized about unseen objects in the outer solar system, only to be proven wrong. Meanwhile, some scientists propose an alternative explanation: these orbital anomalies might be caused by a primordial black hole, formed soon after the Big Bang and potentially captured by our solar system as it traveled through the galaxy.