Turns Out Earth May Not Be A Planet

Michael Tanne
Student Voices
Published in
6 min readMar 21, 2017


It turns out that Earth is not a planet. Asteroid 2016 H03, first spotted on April 27, 2016, by the Pan-STARRS 1 asteroid survey telescope on Haleakala, Hawaii, is a companion of Earth, too distant to be considered a true satellite.

Orbit of Earth and Asteroid 2016 H03

“Since 2016 HO3 loops around our planet, but never ventures very far away as we both go around the sun, we refer to it as a quasi-satellite of Earth,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California.

Asteroid 2016 H03 is proof that Earth has not cleared the neighborhood around its orbit. Therefore, under the definition of a planet vigorously defended by the IAU since the adoption of Resolution 5A on August 24, 2006, Earth is a ‘dwarf planet’ because it has not cleared its orbit, which is the only one of the criteria of their definition that Pluto fails. (I think we’ll eventually discover that very few of the ‘planets’ have cleared their orbits).

Most of us who were baffled by the IAUs declaration and outraged at the obvious discrimination of Pluto knew there was something wrong, even if we couldn’t put our finger on it — we just ‘knew’ Pluto was a planet, right?

Caltech scientist Mike Brown crowed about how he ‘was responsible for Pluto’s death’ and how important this decision was, because it emphasized the importance and number of ‘dwarf planets’ (huge coincidence: Mike Brown is known for his role in the discovery of the dwarf planet, Eris).

At the time Alan Stern, Kirby Runyon and others pointed out that the decision was unscientific, particularly the ‘orbit clearing’ criterion. Well, the IAU’s tortured logic has now come back to bite them in the plutoid.

Here’s what all of us non-scientists intuitively understood all along: “A planet is defined as an astronomical body that “has not undergone nuclear fusion, and having sufficient self-gravitation to assume a spheroidal shape” — in other words, it’s round and not on fire.

How could the distinguished scientists be so wrong?

Here are the 3 problems:
1. The definition of anything must rely solely on its own properties, or predictable interactions with other things. Alkali metals are shiny, soft metals at STP conditions, and highly reactive because they readily lose their outermost electron to form cations with charge +1. Orbital mechanics are so highly complex, that there’s no way to conclude an body can clear its orbit. How much space is that? what other bodies exert gravitational influence? What if there’s been a collision that produced new substellar bodies? How many years is a planet allotted to clear the orbit again? This definition is highly unscientific by its very construction.

2. ‘Civilians’ are upset and confused when they’re told they wouldn’t understand — that experts have decided (‘appeal to authority’ fallacy), especially if they sense an agenda. It’s how teens react when their parents say something irrational then defend it by saying “because I’m your parent and I said so!” The IAU resolution was a process in which 400+ scientists debated and vied to ‘win’ adoption of their favorite definition, as if they were the bishops attending the Council of Nicaea debating the Nicene Creed. Mike Brown, the ‘Bishop of Dwarf Planets’ could declare victory if Pluto was assigned to his diocese. The obvious victim is scientific truth, when everyone in the room has something to win or lose, and the other 9000 members of the IAU weren’t even consulted.

3. Sampling error. We can observe alkali metals in innumerable conditions in nature, in the lab, interacting with thousands of other substances at all different temperatures and pressures. We can even observe their interactions at great distance with mass spectroscopy. This gives us great confidence that our classification is consistent with observed phenomena. However with only 9̶ 8̶ 7 planets to observe, and only under one planetary system, it’s ludicrous to arrive at a definition of planet that requires a predictable interaction with the bodies around it. It’s almost a given that not only will we find our own system doesn’t meet the definition, but since a planet is a planet regardless of what system it’s in (unless the IAU would like to vote against that?) we can’t possibly know that the thousands of extrasolar planets are clearing their orbital paths — meaning it’s a definition which is not only improbable but also untestable.

So Earth itself is now hostage to this debate. Will Mike Brown be responsible for the death the Pluto AND Earth? Or will scientists drop the politics, put on their scientific thinking hats, and restore the faith children everywhere have in the scientific process they are taught, and the intuition we all have that Pluto, is in fact, a planet.

Author’s Note:

This article has been viewed nearly 100k times and I’ve received numerous messages and comments. I appreciate everyone’s interest in the topic of planets, Pluto specifically, and in the process by which human institutions reach decisions on scientific matters. This isn’t about me; I’m not seeking recognition, page views, or followers. Thank you to the grammarians who have spotted my mistakes — I’ve made corrections.

I’m just a lay person who’s been fascinated with the Solar System and space my whole life. Apollo 11 landed Neil Armstrong and Buzz Aldrin on the Moon when I was a small child. I first saw the USS Enterprise enter orbit around a planet to investigate or offer assistance a few years later. I remember laying painted styrofoam balls on the gymnasium floor measuring off the relative distances, amazed at how close Mercury was to the Sun, and how distant was Pluto.

Since then I’ve been a frequent observer of the nighttime skies — noting how bright or how close Venus or Mars were during a particular season, spotting satellites on a campout, or gazing out to where Pluto must be. When I was in high school that was midway between Arcturus and Spica. Since then Pluto’s only moved 52 degrees, crossing the Milky Way to where it is presently.

I’m adding a personal note because of the responses I’ve received. Most have expressed support or added additional dimension to the subject. Others have been critical or pointed out technical inaccuracies, almost as if this were a peer-reviewed scientific paper. I’m usually tempted to go full nerd and start running numbers, but that misses the point of this article.

Many have claimed the matter is ‘settled’, the votes have been cast, and it’s time for ‘you Americans’ to stop making a big deal of it. Statements like this accentuates to lay people that many who claim to be people of science do see this through a political lens. So I want to make a few points:

  1. This is satire. The intent is to shine a light on human folly, particularly those of governing bodies, institutions and society itself, with the goal of some improvement. That so many missed this makes me wonder how many reader complaints The Onion receives each week. In case there was any confusion, I don’t actually think Earth is not a planet.
  2. Science holds itself above the politics and other motives of society, especially astronomy which deals matters sublime and majestic. I’ve visited the birthplace of Nicolaus Copernicus in Toruń, Poland and was grateful that unlike in his time, the nature of the Solar System is now subject to scientific observation. The objectivity of science is something we must protect vigilantly, so I wanted to call out what appeared to be unscientific, even politically motivated activity.
  3. Scientific principles are not subject to voting. Yes, practically speaking there are organizations requiring their members to weigh in on various matters, and taxonomies are more a human construct than fundamental scientific fact. But the nature of a planet doesn’t hang on a vote. That seemed as obvious to me as when King Arthur explained in Monty Python and the Holy Grail “You don’t vote for kings.” Dennis responded that “you can’t wield supreme executive power just because some watery tart threw a sword at you”. Similarly you can’t redefine the nature of a planet that’s existed for billions of years, and of which there are many billions more like it in the galaxy, simply because a group of 400 voted in Prague.
  4. I’m not qualified to argue precisely what ‘clearing the neighborhood’ means, nor the importance of the location of the barycenter of two bodies, one orbiting the other. I understand what most people intuitively do, that a planet is round, and not on fire. The definition of something so fundamental in the universe shouldn’t be subject to such subtle variations. There’s a continuum of bodies from the smallest rock to Jupiter, but there’s a point where they have become round due to their own gravity and occupy a stable orbit, and we’d find the same in any star system. If that means there are hundreds of planets, so be it.

Thank you for reading. I hope it was worth your investment of time. ~Michael