The New Horizons space probe voyage to Pluto has helped to create new interest in learning about our solar system. And it has refocused attention on the issue of Pluto’s demotion from planetary status. I hope to convince you, in this article, that this unfortunate decision should be reversed.
Classification is an important part of all analysis, as it allows us to view and infer patterns of information. The issues raised are not confined to astronomy, as classification is integral to most areas of science and social science, including medicine and politics.
Space scientists are a venerable group. They combine excellent analytical capabilities with the tenacity to study natural phenomena that are not on human timescales. Large numbers can clearly explain their work and convey their enthusiasm to the public. Nevertheless, with respect only to the classification issues I discuss now, my conclusion is that astronomy is behind the times, and with their intense focus on space, astronomers may have lost touch with what is happening on Earth.
I feel comfortable with this viewpoint because I have an academic and professional background in finance, which includes knowledge of financial instruments and related computer programming. Classification issues in finance are much more complex and of more pressing importance than in astronomy. In addition, I studied physics and astronomy for a number of years.
Until 2006, the definition of “planet” meant (1) an object which orbits the Sun and (2) whose size was of sufficient magnitude such that gravity would force it into a round shape. This is called “hydrostatic equilibrium.” Then, in 2006, the International Astronomical Union (the IAU), a group of space scientists who study issues such as the classification of celestial bodies (stars, planets, asteroids, and other bodies) added a third criterion: (3) a planet should “clear its orbital path” of most bodies (such as asteroids), that is, there are no significant celestial objects (other than moons) that share its orbit.
Pluto could not meet criterion 3. Accordingly, it was designated a “dwarf planet.” A dwarf planet is not, (according to the IAU), a planet but a different type of object, as it only meets the first two requirements. Other bodies were also reclassified. Ceres, an asteroid that was originally classified as a planet, was reclassified as a dwarf planet. In addition, “plutoids,” that is, round ice bodies beyond Pluto such as Eris and Makemake, were also designated dwarf planets, because they don’t clear their paths.
Only about 4 percent of the estimated membership voted, with a majority (about 250) voting in favor of the proposal. Most members of the organization were researchers who studied stars and galaxies, not planets. Most planetary scientists are not members of the IAU, and an outside group of about 300 (more than the IAU majority) produced a dissenting view.
Many scientists and much of the public disagreed with this decision. It is not hard to see why. The IAU did not view dwarf planets as members of the larger group of planets—the word dwarf is not used by them as an adjective, as one might expect. Rather, the expression dwarf planet is a two-word noun, as is the term “mountain lion,” which is a different species from a lion—that is why I prefer the term “panther” or “cougar” to mountain lion. To avoid confusion, why not use a different name, such as “orbiting spherical body”? And why use the term dwarf, an objectionable word that has nearly disappeared from common usage?
As to criterion 3, clearing the orbital path, here is an analogy. Years ago, my doctor noted that my weight was increasing. Suppose that I had suggested that, instead of actually losing weight, I could lower my weight classification by simply returning when the office was very crowded, that is, when I didn’t have a clear path through the office and would bump into other patients. If I had said that, she would probably have suggested that I see a psychiatrist. Yet the logic of criterion 3 could result in a planet identical to Mercury being classified differently because it was in another, more crowded area of the solar system.
There were other factors that led the IAU to vote to demote Pluto: (a) Compared to what it defined as planets, some of the bodies in question are small—both Pluto and Ceres are smaller than the moon; (b) their orbits are not in the (relatively) flat plane that the traditional planets traverse and (c) Pluto resembles other icy bodies, plutoids, (noted above) that lie beyond its orbit, in an area called the Kuiper Belt.
But who said one can only be a member of one group? Why can a celestial body not be both a planet and a plutoid? After all, to understand a person, other life form, or inanimate object, one must see all the diverse elements, not try to collapse the information into a single formula.
Some examples: (a) The Internet has demonstrated conclusively that one person can have many diverse interests. (b) The financial industry is a large part of the American economy, and modern financial instruments may have many characteristics that don’t fit any one category. The simplest example is that of preferred stock, which has characteristics of both stocks and bonds. (c) In the political sphere it is often difficult to neatly categorize someone as liberal or conservative, and there are hybrids such as libertarians who are socially liberal and fiscally conservative. (d) A person’s political and spiritual worldview may not match the majority of individuals originating from the same demographic or religious background.
Another objection is that, if plutoids were designated planets, then it would be hard to learn the names of so many of them! Estimates of the number of plutoids run as high as 1,400. Talk about silliness. Most people can only name a few major cities, and many individuals interested in astronomy can only name a relatively small number of stars. That is why we have “apps” on our smartphones. Currently, the United States can’t fly to the International Space Station, a few hundred miles up. By the time we reach the outer solar system, billions of miles away, we almost certainly will have dramatically enhanced our memory capabilities.
I should note further that this attitude does not represent a cosmic perspective. It may well be that these smaller bodies are more prevalent in the universe than ones like the Earth, and that advanced civilizations on other worlds may view a population of a few hundred million as the optimal size. Regarding the size issue, in recent years astronomers have discovered there are many more small red suns than ones like our own Sun. Thus, our own Sun is not representative of stars in the galaxy, so we should learn from that experience and be careful not to categorize small worlds with the ugly term dwarf planets.
The fact that New Horizons has made the public more aware that Pluto has five moons seems to make it seem more like a planet, even a mini solar system, even though smaller bodies can have moons.
If there is interest on the part of readers and the Epoch Times, I will write a subsequent article about my ideas on a simplified approach to classifying solar system objects.
Arthur Wiegenfeld is an independent investor in New York City. He has training in economics, finance, physics, and computer simulation. Comments to firstname.lastname@example.org
Views expressed in this article are the opinions of the author and do not necessarily reflect the views of The Epoch Times.