Earth Is No Longer a Planet!

By Gregory Wonderwheel
(c)2006

Technically speaking, by definition Earth is no longer a planet!

At a meeting of star gazers in the Czech capital, Prague, the International Astronomical Union (IAU) held a 10-day General Assembly of members. The IAU is the official nomenclature body for astronomy that is responsible for naming stars, asteroids and other celestial bodies. On August 24, 2006, in a strange adjustment that demonstrated scientists can act as unreasonably, capriciously, and arbitrarily as any political body and in an act that will go down in the history of science rivaling the stupidity of denying that Galileo saw objects orbiting Jupiter through his telescope, the IAU adopted a new definition of “planet” that does not include Pluto, thus stripping Pluto of the status of planet.

But (in this case of the Emperor’s new cloths) it is an even more incredible fact that the new definition does not include Earth, Mars, Jupiter, and Neptune as planets. They are designated as planets only by the divine grace and fiat of a papal-like indulgence found in a footnote that arbitrarily designates them as planets whether or not they fit the definition! What an absolute legislative sausage that only shows these astronomers to be the space cadets of science. If scientific definitions are worth anything it is only because they are based on observation and rational classification and are not capricious outcome driven definitions.

The initial proposal was one that would have broadened the definition to include several additional bodies orbiting the sun. But there was a backlash of concern for the proposed new definition that pointed out several weaknesses yet offered a proposal with even greater weaknesses that was finally approved.

Nearing the last opportunity to vote before the meeting ended and the definition would have to wait until the next General Assembly, one of the IAU scientists addressed the relatively few astronomers remaining by stating that if they did not adopt a definition after so much debate that they would “look like idiots.” Well, upon that exhortation they adopted a definition that instead of preventing the appearance of idiocy, guaranteed it. This is how fear works. Stampeding in fear to avoid something, the mob rushes right into it.

The IAU has around 10,000 members of which about 2,700 astronomers attended parts of the 10-day General Assembly, but only 424 astronomers remained on the final day of the assembly when the vote took place.

A Definition Is Needed

The problem began when Mike Brown and colleagues at the California Institute of Technology discovered three years ago an object currently designated 2003 UB313 that was being called by some the "10th Planet". The object was measured to have a diameter of 3,000km (1,864 miles) which is a few hundred km more than Pluto. Astronomers were then faced with the question whether this new object was or wasn’t a planet. Since its creation in 1919, the IAU had never before adopted a definition of a planet. So a new definition was needed.

The initial proposal by the IAU's planet definition committee chaired by Professor Owen Gingerich would have immediately added three new planets to the Solar System - the asteroid Ceres, Pluto's “moon” Charon and the distant world known as 2003 UB313. Actually, it has been held for quite a while by not a few that Pluto and Charon are a “double planet.” Quite understandably the official recognition of Charon’s planetary status caused the fear that Earth’s moon might be recognized as a planet next! Additionally, a large minority of astronomers felt that the three new planets were simply the camel’s nose entering the proverbial tent and that there could eventually be dozens if not a hundred objects in the solar system that would become recognized as planets. Obviously this would cause great consternation among school children who have to learn the names of the planets.

While it may seem strange at first glance to lay persons that the “asteroid” Ceres was included as a planet, this is not illogical. Ceres is spherical and contains water-bearing minerals, and possibly a very weak atmosphere and frost. Infrared observations show that the surface is warm. So Ceres definitely does not fit the usual picture of an asteroid as an irregularly shaped cold rock in space.

So the first proposal was chucked into the black hole of parliamentary procedure by being tabled. During subsequent days of debate there were four separate proposals that were also tabled. The core of debate seemed to pit two types of astronomers against each other. On the side of the original proposal were the planetary geologists who wanted to create a definition that relied on the physical description of the celestial body. On the other extreme were the dynamicists - those astronomers who study the motion and gravitational effects of space objects. Astronomers are supposed to have their heads in the heavens with their feet on the ground of scientific method, but here they have shown themselves to have no place to stand and to be no more immune that any other set of people, such as Catholics and Protestants, Sunni and Shia, when it comes to sectarian rivalry over turf wars.

IAU’s Embarrassing New Definition

The adopted definition has gone completely wrong because the scientists were voting on the basis of patently unscientific reasons. What it came down to was that the scientists voted, not for a definition with scientific integrity, but on an outcome, whether or not scientific, that made the number of planets stable at eight. The BBC World Service reported such renowned scientists as
Iwan Williams, the IAU's president of planetary systems science, as saying, "By the end of the decade, we would have had 100 planets, and I think people would have said 'my goodness, what a mess they made back in 2006'." Mike Brown the man who led the discovery of 2003 UB313 absurdly stated, "Eight is enough,"

As someone who grew up with the belief that science is an ongoing endeavor of hypothesis and re-hypothesis with the goal of developing as consistent description of reality as is humanly possible, it is very difficult to hear scientists arguing for a definition on the basis of whether the definition will make eight or 100 planets. My word! Don’t these astronomers know that a definition must have scientific integrity, so that it describes reality regardless of how many objects are found to fit that definition? What a bloody mess these so-called objective scientists have created. They have all apparently spent far too much time with their eyes glued to something other than their telescopes.

Some of the IAU scientists have kept their heads. Professor Gingerich said afterwards that the IAU General Assembly had been “hijacked.”

Dr Alan Stern, head of the US space agency's New Horizons mission to Pluto who was not in Prague for the vote called the new definition “embarrassing” and told BBC News: "It's an awful definition; it's sloppy science and it would never pass peer review.”

Some members are now describing the IAU as the "Irrelevant Astronomical Union".

The New Definition

So, according to the IAU’s newly adopted definition, a "planet" is defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

Well, this definition is so looney that it has to have a footnote explaining that the only bodies that meet this definition are the eight planets minus Pluto. This led to one astronomer at the assembly to quip, “Why didn’t they just adopt the footnote as the definition?”

The third criteria of the adopted definition is just plain illogical, lacking all internal consistency. It states that a planet must have "cleared the neighbourhood around its orbit". This means that the gravitational influence of the world on nearby objects will clear the material in their paths either by pulling it into the planet or sweeping it out of the way with a gravitational tug that sends it away. There’s only one problem with this definition: it doesn’t work!

Pluto fails the neighborhood clearing test because its highly elliptical orbit overlaps with that of the much bigger Neptune. But, this is also the first obvious example of the illogical failure of the “cleared neighbourhood” measures because the planet Neptune likewise has not cleared it’s orbit of Pluto, the very planet the definition was designed to remove!

But even more serious, and causing the greatest dubiousness of the definition, is that in addition to Neptune, the new definition removes the Earth, Mars, and Jupiter from the status of planets, because they too have not cleared their neighborhood orbits. Every time there is a prediction of meteor showers or we see a shooting star, we are reminded that Earth still has space rubble in our path that has not yet been cleared. Sweep, sweep, sweep that neighborhood orbit, and eventually you too can become a planet in the eyes of the IAU.

How stupid can you get? The astronomers have adopted a definition of planet that removes five of the nine planets from planethood! As stated above, they inserted a footnote to the definition that arbitrarily designates Earth, Mars, Jupiter and Neptune as planets whether or not they fit the definition, and they left Pluto off the list in order to exclude it from this capricious dispensation.

Pluto was relegated instead to the second-class status of “dwarf planet” with absolutely no logical boundary or observational basis for the dividing line between planet and dwarf planet. The first members of the new "dwarf planet" category are Ceres, Pluto and 2003 UB313. But the astronomers believe themselves to be clear on one point: a dwarf planet is not a planet since dwarf planets and planets are “distinct classes of objects,” which of course is clearly as absurd and as denigrating as saying that a dwarf human is not a human.

Clearly the entire fiasco of this new definition has no other purpose than to remove Pluto from the ranks of planethood. When five of the nine planets do not meet the scientific sounding standard of “cleared the neighborhood around its orbit” it becomes clear that the criterion is mere smoke and mirrors to create the magician’s distraction from the real purpose: to declare there are only eight planets no-matter what the definition says.

Well, by this colossal mistake the astronomers have proven they are human too. Hopefully they will have the human capacity to say mea culpa and fix their erring ways by adopting a definition that includes both scientific integrity and common sense.

Another New Definition Is Needed

What kind of definition is needed? First, the astronomers must be committed to a definition that describes reality regardless of the number of objects that may eventually fit that definition and does not need a footnote to include objects that don’t fit the definition.

Second, the first two of the criteria that were adopted (orbit around a star while not being a star and being spherical) are based on observation and are perfectly appropriate. In fact some astronomers believe these are the only two criteria required. Dr. Marc Buie, of the Lowell Observatory in Arizona, was one of the first to advocate this position. Before the convocation of the General Assembly, he told the BBC, "I believe the definition of planet should be as simple as possible, so I've come up with two criteria. One is that it can't be big enough to burn its own matter - that's what a star does. On the small end, I think the boundary between a planet and not a planet should be, is the gravity of the object stronger than the strength of the material of the object? That's a fancy way of saying is it round?"

The problem with this definition for many is that it would make many moons, as well as asteroids like Ceres, into planets. For example the Earth and its moon could be recognized as a paired or double planet grouping in a single orbit. For some the objection to this definition amounts to a plain emotional offense and distaste at calling Earth’s moon a planet.

So third, any additional criteria added to the basic two common sense observations must itself meet a test of common sense and observational verification and should be adopted on the basis of scientific peer review methods, such as publication, and not on the basis of emotional political voting at a meeting.

A Taxonomy of Planets

One possible scheme (which I tend toward) is to adopt a taxonomy of planets using the seven chief groups that make up a system in scientific classification of living things. The groups are: (1) kingdom, (2) phylum or division, (3) class, (4) order, (5) family, (6) genus, and (7) species. The kingdom is the largest group. The species is the smallest.

I would propose that there are two kingdoms of celestial bodies, in the first kingdom are the stars that burn their own matter (the autocombustibles) and in the second kingdom are the bodies that don’t burn themselves (the noncombustibles).

In the kingdom of the noncombustible space objects there are two obvious divisions: those that orbit stars (the stellar orbitals) and those that don’t (the interstellar isolates).

In the division of orbitals there are several possible classes: those objects with gravity stronger than the strength of the material of the object thus forming a spherical shape (planets), those irregular rocks whose gravity is not strong enough to shape the object and which orbit a star (asteroids), those irregular rocks that orbit planets (minor satellites), and those objects of ice and dust in highly elliptical orbit transecting the orbits of the planets that shed their materials in tails as they near the sun (comets).

In the class of planets there are the two obvious orders of solid planets and gas planets.

In the order of solid planets there might be division of families based on the materials that compose them. For example, those that are composed primarily of geologic substances such as the silicates and metals might be one family (the stoney planets) and those composed primarily of ice such as the double planets of Pluto and Charon and 2003 UB313 might be in another family (the icy planets).

In the family of stony planets are the logical genera differentiating between the different kinds and amounts of atmosphere (e.g., listing by the element that is greatest in the atmosphere) and the degree of protection of atmosphere by magnetic field.

In the genus of nitrogen rich atmospherics are the species of planets with or without biologic life.

Thus a taxonomy could look like this:
I. Kingdom: Autocombustibles (stars, black holes, etc.)
II. Kingdom: Noncombustibles
A. Division: Stellar Orbitals
1. Class: Planets
a. Order: Solid Planets
1) Family: Stony Planets
a) Genus: Nitrogen Primary Atmosphere (Earth)
(1) Species: Biological Life Planet
b) Genus: Carbon Dioxide Rich Atmosphere
c) Genus: Atmosphere Deprived
d) Genus: (other atmospherics)
2) Family: Icy Planets
b. Order: Gas Planets
2. Class: Asteroids
3. Class: Minor Satellites
4. Class: Comets
B. Division: Interstellar Isolates

This is an admittedly undeveloped draft classification by a layman engaged in brainstorming, and it could, of course, benefit from an intelligent debate by scientists of the IAU. And isn’t this the type of imaginative debate the astronomers of the IAU need to engage in, rather than debating whether having more planets than eight is a burden on the public imagination?

Whatever the final outcome, it is clear that the current absurd definition can not stand if astronomy is not to be held up as the laughing stock of science. So every time you see a shooting star, you may console yourself that though Earth is not yet a planet, we are still working at it.

-end essay-

Appendix:

BBC News stories:

“Crunch time for Planet Pluto” By Nicola Cook, BBC Horizon
http://news.bbc.co.uk/2/hi/science/nature/5099292.stm

“Pluto vote 'hijacked' in revolt” By Paul Rincon, Science reporter, BBC News
http://news.bbc.co.uk/2/hi/science/nature/5283956.stm

News from IAU XXVIth General Assembly:
http://www.iau2006.org/

IAU RESOLUTION 5A
The IAU therefore resolves that "planets" and other bodies in our Solar System be defined into three distinct categories in the following way:

(1) A "planet"[1] is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape[2] , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects[3] except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".
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[1]The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
[2]An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
[3]These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
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IAU RESOLUTION 6A
The IAU further resolves:

Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.

-end appendix-