Is Pluto a Planet?

IsPluto a Planet?

IsPluto a planet?

Fora celestial body to be considered unique, it had to possess uniquefeatures. For the case of Pluto, till it was discovered, it has beenidentified as a planet till the year 2006 when it was found to havefive known moons. The moons are regarded as satellites. These fivesatellites were seen orbiting around planet Pluto. These satelliteseliminated the uniqueness that Pluto used to enjoy as a planet. Aminor planet discovered in the late 1970’s by the name Chiron wasfound to have a relatively higher mass than Pluto raising questionsover its recognition as a planet. Between the 20thand the 21stcentury, outside the solar planet were discovered several otherobjects were discovered which were similar to Pluto in every aspect.The most notable object was the Eris, which exceeded the mass ofPluto by 27%. IAU decided that there were several objects thatresembled Pluto and keeping Pluto as a planet it meant that all theother objects that had similar characteristics to Pluto should beincluded in the list of planets. But this again was not possiblebecause all the eight other planets that have been accepteduniversally have special features that make them be distinguishedfrom others. Since this other objects Pluto included have no specialfeatures and they seem similar making it impossible to differentiateone planet from the other, the only option by the IAU was todisqualify Pluto as a planet (Kortenkamp, 2007).

Toanswer these question as to whether Pluto is a planet or not, theuniversally agreed definition of a planet should be reviewed. IAUheld a meeting to determine and discusses the matters arising as towhat features a planet should have or what should be the correctdefinition of a planet. This idea came up because of the severalplanets Pluto that were discovered. The Union came up withdefinitions of both the dwarf planet and the planet. Thesedefinitions were voted on by the members who positively agreed on theproposed definitions which disqualified Pluto as a planet. Takinginto consideration that there are dwarf planets as well, bothdefinitions should be reviewed, and Pluto studied keenly to determinewhether it is a planet or a dwarf planet. The InternationalAstronomical Union is an international body that has been given theauthority and mandate to name all the celestial bodies in space andthe features these bodies may possess. The assigning of the names isdone using the internationally accepted rules. The InternationalAstronomical Union (IAU) came up with a universal definition in theyear 2006 to distinguish between dwarf planets and arose planet. TheIAU defined the term planet as a celestial body that orbits round thesun and it has a substantial mass that makes it assume an equilibriumshape, and also the neighborhood around its orbit is very clearwithout anything visible around it (Weintraub, 2007). Examining Plutofrom this definition, it orbits around the sun just like all theother eight planets are doing and also its shape that is round makesit have a hydrostatic equilibrium. From this point, Pluto seems to bea planet and not a satellite. A contradiction arose when IAU defineda dwarf planet. A dwarf planet is a celestial body is that orbitsround the sun has a sufficient mass that enables it to have anequilibrium shape, the neighborhood around where it orbits is notcleared, and also it should have the features of a satellite. Goingby this definition, the only difference between the two planets isthat of a clear neighborhood. Studying Pluto from this point, in itsimmediate neighborhood was Eris. This qualifies Pluto to be a dwarfplanet alongside Eris. Both of them did not meet the criteria set tobe called planets and, therefore, Pluto was disqualified on thisground from the list of planets. Because of this conclusion, Plutowas added to the members of the minor planets (NASA, 2015).

Despitethis agreement by the majority astronomers who are members of IAUthat Pluto is no longer a planet, some of the astronomers stillinsist the Pluto is still a planet and should not be deprived off itsstatus of being a planet (Mortenbrey, 2015). The reasons they putforward are that Pluto has a cluster of moons. As well, they arguethat all the dwarf planets should be classified as planets alongsidePluto. This class of astronomers has come up to defend heavily theirstand that Pluto should continue to be regarded as a planet. Theystart by criticizing the definition that the IAU came up with whichled to demoting Pluto. They argue that this definition was unfairbecause it relied on mass and the shape of the planets. This two werenot known by 1930, and there was no possible way they could have beenknown. The new definition as well suggests that the planet should beround whereas not even the famous planet Earth is round. The ruleunder which Pluto was disqualified as not having a clear neighborhoodis under attack from this group of astronauts (NASA, 2015). Theyargue that there are Trojan asteroids at planet Jupiter, there areNears around planet Earth and also there’s even dust around it.They argue that this rule if applied will zero down the number ofplanets in the solar system. The concept of the planet clearing itsorbit is under attack under attack as well because as per theseastronauts, the idea is not practical regarding the volume it shouldclear which keeps increasing as the distance of that particularplanet increases from the sun. Because Pluto is the furthest distancefrom the sun, clearing will be the most difficult thing for it. Thepoor neighborhood of Pluto has been criticized as well. They identifyplanet Mars as having stayed in the cluttered region which shouldhave disqualified it as a planet, but it’s still known as a planet.Mars even had the massive Jupiter around it that helped it clean itsorbit. They believe that definition of a planet by IAU is timedependent, and there’s no effort which was made to know the historyof these bodies before this status was assigned to them (Mensing &ampFaure, 2007). They as well propose that defining an object based onits position is too remote. They prefer terms like star clusterslatter than star clusters as proposed by IAU. These astronautsquestion the way and transparency through which this definition waschosen. They remain to wonder if science should be done in thebackroom or in an open forum where members contribute freely andopenly. They feel that this definition of a planet was botchedbecause even a dwarf planet is also a planet. They suggest that thefunding to the space to go and do more research about Pluto willreceive a serious setback because of the decision to demote Pluto asa planet. As per these astronauts, these changes puts doubt in thescientific classification already done to be real rather thaninfluenced by the human construct. Lastly, the opposing astronauts todemoting Pluto argue that Eris that has been termed as bigger thanPluto, its orbit is inclined to the ecliptic.

Toconclude, Pluto was a victim of multiple discoveries that werediscovered in the solar system. The discovery gave rise to severalobjects that were similar to Pluto in every manner. This made Plutoloose the uniqueness it had and it was declared no longer unique. Thediscovery of the many objects gave room for a proper definition ofwhat a planet is. The IAU used the power bestowed over it to come upwith definitions which were voted by its members to make themuniversally acceptable. It’s after the members agreed on thedefinitions that the union demoted Pluto as a planet and it was putin the same class as the other objects which it had the same featuresand size with. The current learning materials should be now edited byredefining the solar system to contain the eight planets and not nineplanets as it was previously known. The IAU has set the necessaryfoundation for making the study of the solar system interesting.


Kortenkamp,S. (2007). WhyIsn’t Pluto a Planet? A Book about Planets.Capstone Publishers.

Mensing,M.T &amp Faure, G. (2007). Introductionto Planetary Science. The Geological Perspective. SpringerScience &amp Business Media.

Moltenbrey,M. (2015). Dawnof Small Worlds. Dwarf Planets, Asteroids, Comets.Springer Publishers.

NASA.(2015). Pluto:The `Other` Red Planet.Retrieved from

Weintraub,A.D. (2007). AHistorical Journey through the Solar System.Princeton University Press.