Good ol’ Pluto is no longer a planet. It has been demoted to the status of being a ‘dwarf planet’. As expected, the decision is not without its critics.

A vote at the International Astronomical Union’s (IAU) 10-day General Assembly in Prague this summer has demoted Pluto to the status of a dwarf planet. The IAU has been the official naming body for astronomy since 1919.

Raising consternation amongst the astronomers community is the fact that only 424 astronomers who remained in Prague for the last day of the meeting took part in the voting – thereby implying that the decision is far from universal.
An initial proposal by the IAU to add three new planets to the Solar System – the asteroid Ceres, Pluto’s moon Charon and the distant world known as 2003 UB313 – met with considerable opposition at the meeting. Days of heated debate followed during which four separate proposals were tabled.

Eventually, the scientists adopted historic guidelines that saw Pluto getting relegated to a secondary category of “dwarf planets”.

It would only be appropriate  to remind ourselves here that Pluto’s official status as a planet has been a constant subject of controversy, fueled by the past lack of a clear definition of planet, since at least as early as 1992, when the first Kuiper Belt Object, (15760) 1992 QB1, was discovered.

With betterment of telescope technology, further discoveries of trans-Neptunian objects, some of comparable size to that of Pluto, were made by scientists in US and Europe. In 2006 the matter came to a head with the need to categorize and name the recently-discovered trans-Neptunian object Eris, which, being larger than Pluto, was thought to be at least equally deserving of the status of ‘planet’.

“To most people the word “planet” is more cultural than scientific. It is part of the mental landscape that we use to organize our ideas of the universe around us. The best analogy I can come up with is with the word “continent.” The word sound like it should have some scientific definition, but clearly there is no way to construct a definition that somehow gets the 7 things we call continents to be singled out. Why is Europe called a separate continent? Only because of culture. You will never hear geologists engaged in a debate about the meaning of the word “continent” though.

Astronomers might be wise to learn from the geologists. Let culture define “planet” and let astronomers get back to the more important business of actually doing science.

Michael E. Brown (Discoverer of dwarf planet Eris)

In the wake of increasing debates within the IAU, Julio Fernández and Gonzalo Tancredi of Uruguay proposed of a redefining of the term ‘planet’; so that other objects beyond the traditional nine planets could also be included in the planetary family.

Eventually, on August 24, 2006 in Prague, Czech Republic, the vote removed Pluto’s status as a planet and reclassified it as a dwarf planet.

However, almost immediately after and since  the adoption of the new definition, there has been criticism of both the substance and the process of arriving at the decision.

Within five days of the new IAU Planet Definition over 300 scientists signed a petition that opposed the new definition. Interestingly, the petition too has been criticized; because unlike the wide national identities of the voters at the IAU assembly,  nearly all of its signatories are Americans. The petitioners also failed to propose an alternative definition, so their signatures are no indication that they are all of similar views.

Among the general public, reception is mixed amidst widespread media coverage. Some have accepted the reclassification, while some are seeking to overturn the decision, with online petitions urging the IAU to consider reinstatement.

Within five days of the new IAU Planet Definition, over 300 scientists signed a petition that opposed the new definition. The full text of the petition says: “We, as planetary scientists and astronomers, do not agree with the IAU’s definition of a planet, nor will we use it. A better definition is needed.”

The decision has its cultural and societal implications too. It will affect the astronomical artifacts and toys industry. Educational books need to be revised. Something that prompted the editors of the 2007 edition of the World Book Encyclopedia to hold off printing until a final result had been reached.


Author. Entrepreneur. Filmmaker. Journalist.

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