Is there a hidden massive planet in the outskirts of the Solar System? Scientists recently questioned the planet nine hypothesis. Credit: ESO/Tom Ruen/nagualdesign

Twist of Gravity: The Enigmatic Hunt for Planet Nine

Okay, so is there a ninth planet hiding in our solar system, one that we haven't discovered yet?


On the adventurous path to discovering a ninth planet in our cosmic backyard (sorry Pluto), a duo of theoretical physicists are shedding light on a different trail. They argue that the peculiar orbital behaviors, that ignited the search for a ninth planet, might be pointing towards a fundamental change in how we understand gravity, especially beyond the realms of our solar system.

Researchers Harsh Mathur, a physics professor at Case Western Reserve University, and Katherine Brown, an associate physics professor at Hamilton College, embarked on this exploration, delving into the effects the vast Milky Way galaxy might have on distant solar objects, under the guiding light of a theory known as Modified Newtonian Dynamics (MOND).


Gravity Redefined: The MOND Theory

The MOND theory nudges the centuries-old Newton’s law of gravity to the side when gravitational acceleration reaches a minuscule threshold, allowing a different gravitational playbook to take center stage.

The theory, initially crafted to decode the rotational mysteries of galaxies, has gained traction amongst a faction of the scientific community as a plausible alternative to the elusive “dark matter,” an inferred form of matter believed to exhibit gravitational pull yet remains invisible to the electromagnetic spectrum.

“MOND is proficient in decoding galactic-scale observations,” asserts Mathur, “nevertheless, its implications on our outer solar system were a revelation.”


Their groundbreaking work, recently showcased in The Astronomical Journal, is not the duo’s first rendezvous with MOND, yet the local effects of this theory caught their eye following a 2016 announcement by astronomers about certain outer solar system objects exhibiting orbital oddities, hinting at a potential ninth planet.

Unveiling Cosmic Secrets Through Orbital Anomalies

Historically, orbital anomalies have been cosmic breadcrumbs leading to monumental discoveries. The revelation of Neptune was triggered by its gravitational dance with nearby celestial objects, while the subtle orbital precession of Mercury fortified Einstein’s theory of general relativity. More recently, orbital dynamics unveiled the presence of a supermassive black hole at the heart of our galaxy.

Driven by curiosity, Brown questioned if the MOND theory could align with the observations propelling the hunt for the ninth planet. Our goal was to investigate if the data backing the Planet Nine hypothesis would essentially dismiss MOND, she explained.

Contrary to expectations, Mathur and Brown discovered that MOND precisely forecasts the observed clustering. Over millions of years, the gravitational choreography of the Milky Way could entangle the orbits of some distant solar system objects, pulling them into alignment with the galaxy’s own gravitational symphony.

A Striking Alignment: Unfolding the MOND Narrative

The alignment witnessed when juxtaposing the orbits from the Planet Nine dataset against the Milky Way’s gravitational field was “astounding,” in Mathur’s words.


Despite the excitement, the researchers exercise caution, acknowledging the limited dataset and the myriad of possibilities awaiting exploration. Some in the astronomical community argue that the observed orbital peculiarities might stem from observational bias.

Irrespective of the ultimate conclusion, Brown emphasizes that this endeavor underscores the outer solar system’s potential as a fertile ground for probing gravity and delving into fundamental physics conundrums.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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