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Is Pluto a Planet?

Whenever questions arose on how many planets exist in the Solar System, any learned individual would say, ‘Nine’. Generally, most current research has reached the conclusion that there are only nine planets in the Solar System, i.e., Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and finally Pluto. However, various astronomical studies try to prove that Pluto should no longer be a planet. In 1930, a scientist named Clyde W. Tombaugh discovered Pluto in the Lowell Observatory, Flagstaff, Arizona. The mass of Pluto was calculated after the discovery of its biggest moon, Charon, in 1978. The size of Pluto is presently 2,400 km (1,500 miles) across.

An eleven-year-old girl in Oxford, England, coined the name Pluto, which refers to a Roman god of the underworld. Initially, this planet possessed the name Planet X. According to the current research, it may occur that Pluto can no longer be considered a planet. One of the main reasons for this deduction is that the composition of Pluto coincides well with that of other non-planet bodies. In addition, Pluto in its orbit, together with its moons, appears part of the large body of objects in outer space, also termed as the Kuiper Belt (Rothery, 1999).

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The Solar System is deemed to consist of nine planets. However, controversies persist as to whether Pluto should be included among the nine planets or not. Most characteristics of Pluto speak in favor of its being one of the nine planets. However, certain features of this planet do not allow us to be absolutely confident of this. In fact, the counterarguments seem to outweigh the supporter’s arguments. Hence, the majority of astronomers reject the idea of Pluto being a planet (Green, 2003).

As earlier stated, Pluto was ruled out as a planet because its composition seemed identical to the other asteroids beyond Neptune. In addition, the composition of these asteroids differed completely from that of the other eight planets in the Solar System. Secondly, Pluto was viewed as too small to earn the name ‘planet’. This point also faced controversies, since the size may not necessarily determine this. However, the small size of Pluto still matters since Pluto is smaller than nine other moons in the outer space. Some of these moons include Callisto, Titan, Ganymede, Triton, and Europa (Martin, 2012). Other discoveries proved that Pluto contained similar gaseous and mineral content as other asteroids. Some of these asteroids include Ceres, Pallas, Juno, and Vesta. Initially, these asteroids were called planets. However, after their numerous discoveries in space, their name changed to asteroids.

Theories that still present Pluto as a planet of the Solar System

For instance, Pluto exerts massive gravitational pull over the objects that lie around its orbit. Secondly, it has its own moons. However, Pluto possesses no clear neighborhood around its orbit. Thus, several astronomers concluded that Pluto is a ‘dwarf planet’ and ‘small solar-system bodies’. The International Astronomical Union uses the above points to rule out Pluto as a planet. Furthermore, these disputes are based on the definition of the word ‘planet’. This organization argued that a planet refers to a heavenly body that lies in its own orbit around the sun. It possesses massive gravitation that allows it to maintain its hydrostatic equilibrium elliptical shape. In addition, a planet possesses a clear surrounding around its orbit. The features described in the definition tallied with those portrayed by Pluto. However, the fact that Pluto lacks a clear surrounding around its orbit excludes its status of a planet, but a ‘dwarf planet’.

Another reason why Pluto is a dwarf planet is the fact that other objects larger than Pluto was discovered in the proximity. For example, the object known as Ceres has the same composition as Pluto. Another object 2003 UB313 (Xena), discovered by Brown, is also bigger than Pluto. Other hundreds of similar heavenly bodies were revealed after the discovery of Ceres and 2003 UB313. Thus, it appeared unrealistic to term them all as planets, which could lead to immense confusion in textbooks and articles. Hence, all these bodies earned the name dwarf planets or asteroids (Stuart, 2001).

One reason as to why Pluto lacks the defining characteristics of the other planets is the fact that its largest moon, Charon, is half of Pluto’s size. All the eight planets in the Solar System possess a large range of moons that rotate around them. In addition, the size of these surrounding moons is almost an eighth of the planets. Pluto lacks the ability to clear its rotational field of the other numerous asteroids that surround it. In addition, it has a congested orbit. The other planets dominate their surrounding and possess the capability to clear their pathways of numerous asteroids. This makes their orbits appear clearer. Contrary to the features of other planets, Pluto only appears to be a massive ice ball. This feature portrays characteristic of the other numerous bodies beyond Neptune. This provides another proof that Pluto is more of another asteroid than a planet.

Extensive researches in the attempts to classify Pluto in its rightful category still continue. The uncertainty amongst different astronomers led to Pluto acquiring a dual definition. It possesses both characteristics of a planet and the Trans-Neptunian Objects (TNOs). Most astronomers still protest against these definitions since they still think that there is no solid proof that Pluto is not a planet. Thus, it takes more research to finally establish the fate of Pluto as a planet.

Pluto has been viewed as a very small planet. In addition, it is extremely far away from the Sun, about 3.6 billion miles away. It also orbits far away from the planet Neptune. Thus, it appears similar to other Trans-Neptune Objects. Some astronomers also call it a plutoid. According to NASA, a plutoid simply refers to a dwarf planet that exists millions miles away from the planet Neptune. NASA discovered this by use of telescopes in their study and research on other existing heavenly bodies.

However, despite the fact that Pluto still does not stand as the ninth planet in the Solar System, it still possesses some features that some of the other eight planets lack. For instance, Pluto possesses about five moons. On the contrary, the planet Earth possesses only one moon; Mercury and Venus possess none. This is an extraordinary situation due to the extremely tiny size of Pluto compared to other planets with a lesser number of moons surrounding them.

The elliptical orbit of Pluto, which occurs rather sharply inclined, gives another proof of it appearing as a dwarf planet. Furthermore, apart from occurring immensely rocky, it also appears largely iced in nature. It possesses a lower gravitational pull around it as compared to the other eight planets. The fact that it originates right from the Kuiper Belt also rules it out as one of the planets of the Solar System. The origin of the other eight planets is not related to the Kuiper Belt. The other planets formed because of the convergence of remaining dust particles. These dust particles originated from the Sun during the process of its formation. To this effect, all the nine planets displayed a neat and uniform alignment in their orbits around the Sun. Pluto lacks these distinctive features of origin and alignment.

The government has a different outlook on the matter at hand. Though the impact of the government has appeared narrow, all the tours in space were authorized by it. The final data that attempt to prove that Pluto is a planet must be evaluated well by the government. This happens since the final deductions become part of textbooks used by learners in various institutions. In addition, failure to publish the right information may cause confusion in the whole learning process. Thus, for educative purposes, Pluto still exists in textbooks as the ninth planet in the Solar System.

The arguments that try to rule out Pluto as a planet in the Solar System may seem true. However, a number of astronomers still disagree with the idea that Pluto is a plutoid.


The right answer to whether Pluto is a planet or not appears as ‘yes’. The numerous researches carried out by the International Astronomical Union provide enough evidence for this answer. All the studies that this union has carried out since 1930 provide the required evidence. In trying to prove whether Pluto is a planet or not, many other discoveries have occurred. The presence of other bodies beyond the orbit of Neptune, which possess the same composition as Pluto, was one such discovery. It ultimately led to the questioning of whether Pluto is a planet or not.

Eventually, this study ruled out Pluto as a planet. This occurred since the origin of Pluto was different from that of the other eight planets. It seems that Pluto possesses a lower gravitational field around its orbit. This hinders it from swiping away the foreign bodies that surround it as it revolves on its orbit. To that effect, the surrounding of Pluto occurs relatively crowded.

Other than that, astronomers such as David Jewitt ND Jane Luu also contributed to proving that Pluto is not a planet. They discovered other planets of the Kuiper belt that portrayed similar characteristics to Pluto. The masses and compositions of those planets appeared similar to those of Pluto. In fact, one of these bodies occurred larger than Pluto, e.g., as Ceres, which has the same composition as and a larger size than Pluto. Owing to the fact that Ceres is a member of the Kuiper Belt, this showed that Pluto had a different origin as compared to the other planets.

The elliptical shape of Pluto’s orbit makes it revolve around the sun in an almost oval orbit. This makes it different from the other planets since they revolve in almost circular orbits. The reason for this difference includes the fact that these other planets possess larger gravitational pulls. In addition, they possess a control over the asteroids and objects that lie within their orbits. Pluto lacks these features since the gravitational pull around it is negligible (Weintraub, 2007). More research is needed since some astronomers still term Pluto as one of the planets in the Solar System. They stipulate that Pluto is as a mere Trans-Neptunian Object. These clear controversies call for more research and studies on the subject.

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