Pluto: Is It a Dwarf Planet?

The International Astronomical Union (IAU) had classified Pluto as a non-object planet in solar system. This classification was based on the orbital aspect in accordance of the Sun. Subsequently, this definition had created many debates why the IAU categorized this planet into non-planet. Many scientists argue that Pluto is a planet, but the others suggested it is dwarf planet. However, many disagreed scientists believe that the reason of classification was merely not scientific as the perception of the orbital to the Sun. Was it a dwarf planet?

Image of Pluto as dwarf planet presented by NASA

Pluto was discovered was discovered by Tombaugh, an American astronomer, in 1930. It is located in the Kuiper Belt which forms a ring behind the Neptune. The name of Pluto was based on myth which has meaning the god of the underworld. The first person who coined the name was Venetia Burney who was a teenager in Oxford, England. Today, many debates have been occurred among scientists as this planet had been considered as dwarf planet. The arguing was happened because the IAU believe that it does not have criteria in revolution for the Sun.

What makes Pluto becoming the Dwarf Planet?

Well, the debates were started because of the definition of planet proposed by the IAU. Astronomers of the IAU believe Pluto does not orbit to our star which is the Sun. And even more, they suggested also Pluto has nothing do to in orbiting which means nor it is a rogue planet. The others scientists argued that this definition does not make sense as there is not objects in the universe including in our solar system have clear zone to do orbiting.

Mathematically speaking, if an object must have a clear zone so it means differently. It is because the planet must have an exact pattern which is not alternate. Therefore, K. D. Runyon considered this definition is merely intuition so it does not have scientific and technical reasons. By quoting the Runyon’s definition, a planet is a sub-stellar mass body that has never undergone nuclear fusion that has sufficient shape adequately to assume a spheroidal shape adequately described by a triaxle ellipsoid regardless of its orbital parameters.

As we know that the orbital patterns will always change because of gravitational interferences or perturbations. Therefore, astronomers utilize the derivation of Newton’s Law of motion and gravitation universally and collectively. This paradigm leads us to systems which orbits classically – proposed by Kepler. In short sentence, the objects in space must have ellipse, parabola and hyperbola so that they could be classified as planets in term of two dimension. However, based on this assumption we avoid the interactions as if we neglect the Newton’s Law of universal gravitation. As we knew that planet’s gravity generated by its own rotation governs every object near to its.

Issues will come if the definition of planet as mentioned

The main issue is about the space exploration in identifying whether an object is a star, planet, dwarf planet, asteroid, comet or others. If we only classify an object only based on the orbit of the Sun, then we could categorize it as planet too which means comet, asteroid, and dead star which have perhaps orbiting the sun as planet. Therefore, Runyon proposed that a planet must follows these criteria based on his definition

1. It has a mass body
2. It never does fusion reaction on its nucleus
3. It has an obvious self-gravitation, which
4. Makes it a sphere form, which also
5. Has triaxial ellipsoid in accordance of its orbits

The main issue also leads us to confusion in defining the object as a planet. In other words, the definition proposed by Runyon is based on the geophysical and astronomical aspects which can be considered as complete characteristics. On the other hand, the IAU statements which are written in Runyon’s paper could show their inconsistency as they only employ giant, ice giant, and terrestrial to describe geological and geophysical aspects of a planet. This will produce confuse to both educators-students and practitioners.

Conclusion

Based on the geological and geophysical factors, a planet must not act similar with the stars – such as the Sun –, which does not employ nuclear fusion. It must have its own gravity which can affect the shape to become sphere and the gravity also affects the orbits into triaxial ellipsoid. Subsequently, throughout these classification, Pluto is absolutely a planet which orbits on the solar system.

Reference

A geophysical planet definition. K. D Runyon, S. A. Stern, T. R Lauer, W. Grundy, M. E. Summers, K. N. Singer. Lunar and Planetary Science XLVIII (2017)