It is possible I made a post on this event a semester ago when it occurred, but my archive has become too dense and I am too lazy to look for it, and New Horizons brought it back up. It was the start of the Spring semester in my Engineering class, and we were meeting our temporary teams. The girl next to me, Sarah, was easy enough to have a conversation with in terms of getting her to talk but difficult in the sense of what she had to talk about. This is of course quite a common problem in this department but despite that it still struck me as abnormal. There had been plenty of articles showing up online that month claiming Pluto had gained its planetary status back and everyone celebrated, so I asked their opinions over it. Sarah had not heard this, and her response was, “Really? I didn’t know that. I didn’t know they could do that. Well, good for Pluto then, I guess.”
“Well, if they can take it away, they can give it back right? I mean that’s why everyone our age and the millennials were ever upset about it, nostalgia over a pneumonic song.”
It turned out she had thought Pluto had left the solar system. It had just floated off and stopped orbiting the sun, which I suppose could happen to a planet somewhere. The rest of us were given a moment to look at her and imagine our childhoods in 2006 learning that the ninth planet had left us instead of being reclassified through a democratic debate in the scientific community.
Those articles were commenting on a few smaller scientific communities that autonomically declared Pluto should be called a planet, but if you listen to anyone talk about Pluto during the New Horizons flyby the majority of scientists will still classify it as a dwarf planet, mostly because each one comes to the conclusion by asking and answering the question themselves with logic and reason, the way science and education should be done.
Most people argue Pluto’s status on size, which, while it does classify it as a dwarf planet, is not where the argument ends. Yes, calculations of Pluto’s size became lower and lower throughout the twentieth century, from the size of Earth, to Mars, to what we know now. Yes, there are moons bigger than Pluto, several. In fact, our moon is bigger than Pluto. The argument that if Pluto is a planet, the moon should be, however, is invalid because of their positions or roles in the solar system in relation to the sun. Pluto orbits the sun.
However, Pluto’s own moon, Charon, is not necessarily its moon at all. It is .125 the size of Pluto, in volume, .116, in mass, and .52 diametrically (that’s over half). To put that in perspective the moon is .02 of Earth, in volume, .012 in mass, and .2727 in diameter. In fact, Charon does not technically orbit Pluto, but Pluto and Charon both orbit a point, simultaneously orbiting the sun, outside of their surfaces, because of Charon’s pull on Pluto. While the classification has not been officially changed, it is for these reasons that the two objects can be considered a binary dwarf planetary system.
While Pluto’s size alone in relation to the other planets is not enough to declassify it, the nuances around its abnormality does provide more evidence. The eight planets can be easily classified into two groups (coincidentally equal ones). The two groups share many qualities determined by the formation of the solar system. The inner planets are smaller and have rocky surfaces while the outer planets are called gaseous giants. Pluto is the anomaly, being the “planet” furthest from the sun we should expect another gas giant, but it is a rocky asteroid smaller than any of the inner planets. However, in the video a mutual of mine posted that I shared on facebook of Colbert interviewing Neil deGrasse Tyson, Tyson explains that if we were to classify planets based on their relative sizes to each other or to Earth, Pluto could be a planet, as Pluto is only a fifth of the size of Earth while Jupiter is eleven times larger than Earth (radially). Two strange points brings us beyond just comparing objects to Earth, however. Like we said, Pluto does not fit the behavior of the other outer planets, in size or material. Secondly, there are other objects in the vicinity of Pluto that fit its characteristics as well, larger. These objects are asteroids of the Kuiper belt.
Pluto would indeed make more sense, along with its orbiting moons, including Charon, classified as an asteroid of the Kuiper belt. It is not a gas giant; it is a asteroid that orbits in the beyond Neptune.
This path is so abnormal for a planet that its orbit is seventeen degrees, with the sun as an axis, off from the orbits of the eight planets, all relatively parallel with one another. In fact, two-dimensionally, it doesn’t form the same ellipse the others are. It’s orbit is so off that it actually crosses Neptune’s, meaning for part of Pluto’s year it would be the eight planet from the sun.
Although I am on the downer side of the controversy, I always find it interesting.