Are We About to Discover a Ninth Planet . . . Again?

We’ve been discovering the ninth planet for almost 200 years now. What makes this time different?

In 2014, something strange was found with the orbit of the dwarf planetoid, Sedna. Sedna lies far beyond Pluto and is known as a trans-neptunian object. It and a number of other trans-neptunian objects share an irregularity in their orbits that might point to what has been called a “giant perturber.”

Or a ninth planet.

If this planet exists, it could be 10–15 times the mass of Earth.

It may be a gas giant similar to Neptune or it could be a Super-earth — a planet just a bit bigger than our own.

And unlike anything else in our solar system.

There’s no way to know because we haven’t seen it yet. But scientists are confident this planet will be found any day now.

Yet this isn’t the first time we’ve thought we found a ninth planet.

Over 170 years ago, almost immediately after the discovery of Neptune, scientists began speculating on the existence of another planet beyond Neptune’s orbit.

2 years later, Jacques Babinet, recalculated Neptune’s mass and orbit and found a discrepancy that seemed to point to the influence of another planet. He called the proposed planet “Hyperion” and estimated it to be about 12 earth masses. Actually pretty close to the hypothetical planet we are detecting today.

But Neptune’s discoverer, Urbain Le Verrier, strongly refuted Babinet’s hypothesis but that didn’t stop others from finding their own ninth planet candidates.

In 1909, an eccentric scientist and self-proclaimed “greatest astronomer in the world”, T. J. J. See not only asserted that there was a ninth planet, but there also had to be a tenth and an eleventh. He named his ninth planet, “Oceanus” and gave its distance from the sun but never provided any evidence for his claims and there’s no indication he ever made any observations of the so-called whereabouts of his ninth planet.

But 2 years before T. J. J. See’s unfounded speculations, another American astronomer, Percival Lowell, began a search for a trans-neptunian object he called Planet X.

Lowell believed aberrations in Uranus’s orbit were evidence of a ninth planet and he was determined to find it. For years he had been derided by the scientific community for promoting the idea of canals and intelligent life on Mars.* But Lowell hoped that the discovery of Planet X would rehabilitate his reputation as a serious scientist. However, after searching for more than a decade, he died without finding anything.

The search for Planet X didn’t end with Lowell’s death though.

The task for finding the ninth planet was handed to a 22 year old farm boy named Clyde Tombaugh.

Utilizing Lowell’s predicted location of Planet X, Tombaugh detected an object moving across the sky, using a new technique of comparing differences in photographic plates through a microscope.

His discovery was soon confirmed and Venetia Burney — an 11 year old girl from England — gave the newly discovered ninth planet the name Pluto.

But Pluto was not Planet X. It was much too small to have caused the irregularities observed in Neptune and Uranus’s orbit.

The fact that Pluto had been found in Lowell’s predicted location was nothing more than a coincidence.

But the search for Planet X didn’t end there.

Over the years since the discovery of Pluto, there have been many searches for another, even more elusive planet.

And while Planet X remained difficult to find in the night sky, it began appearing everywhere in popular culture.

Planet X turned up in movies, TV, books, and comic books. It was home to hostile alien races and explorers alike. It was even purported to be on a collision course with Earth from time to time.

But the Voyager 2 flyby in 1989 revised Neptune’s mass and eliminated any orbital discrepancies. This effectively ended the search for Planet X once and for all.

But that didn’t mean there was nothing to find out there on the edges of our solar system.

Many icy worlds have been found in the subsequent decades. But none of them big enough to be called planets.

But arguably the biggest controversy these days is not whether or not there is a ninth planet out there, but what exactly can be called a planet in the first place.

In 2006 the International Astronomical Union tweaked the definition of a planet to include the ability to clear the neighborhood of its orbit. That means, a planet not only has to orbit the sun and be nearly round, its orbit must be clear of debris and other objects.

This is what knocked Pluto out of the planet category. It inhabits an area of space called the Kuiper Belt which is filled with icy worlds of all kinds. Pluto just doesn’t have enough mass to have cpushed them out of the way.

But this decision hasn’t been devoid of controversy. Geophysicists from the New Horizons mission that swung by Pluto in 2015 have proposed a much simpler definition of a planet.

According to them, a planet is a thing that’s big enough to become round by the force of its own gravity.

Simple, right? Planets are round. What’s wrong with that?

Well, if we go by that definition not only does Pluto become the ninth planet again, it becomes 1 of a approximately 110 planets in the solar system.

The moon is a planet by this measure.

So not the most practical definition.

Since its first inklings in 2014 — when it was merely the perturbation in the orbit of a small planetoid — the evidence for a ninth planet’s existence has only grown. A number of other worlds show irregularities in their orbits and several other research teams have confirmed that these irregularities seem to be the result of an unseen influence.

At its estimated size — about 4 times the width of Earth — the Giant Perturber should be able to be seen with a professional telescope.

But the sky is big and the search area is massive. But with enough eyes looking, it seems inevitable that the ninth planet will eventually be found.

We’ve been discovering the ninth planet in our solar system for 170 years now. So if we discover another planet soon lurking in the outer depths of our solar system — whether it’s the ninth, tenth or one hundred tenth planet — we can expect to keep discovering new members of our solar system far into the foreseeable future.

Video Version Here: https://www.youtube.com/watch?v=dbms5Nd1BEk

*I actually talk all about that in another piece.