How Pluto Lost Its Status As A Planet

As I was a young student, I learnt that our solar system consists of 9 planets, and Pluto was the last among them from the sun. I was also taught that Pluto was the outermost and coldest planet in our solar system. But in the meantime, Pluto has been declassified as a planet (since 2006), and is now known as a dwarf planet. What the actual fudge? How did that happen? And why? I had so many questions when I came to know of this. This article is an attempt to get some answers as to why Pluto is no longer considered a planet of our solar system.

This essay is supported by Generatebg

The Background

Pluto was discovered in 1930 by an American astronomer Clyde Tombaugh. It was the first object to be discovered in the Kuiper Belt, a large region of icy bodies beyond Neptune’s orbit. Pluto is about 3,700 km (2,300 miles) wide and has a mass of about 6.4 x 10^22 kg. It takes 248 years to orbit the Sun once. It’s safe to say that none of us would live (in present times) to experience one Pluto-year.

The Anomaly:

Pluto’s discovery led to a lot of excitement as it was the first planet discovered after Neptune. However, it was soon found that Pluto’s mass was too small to have cleared its neighborhood of other objects as Neptune did. This led to the discovery of Eris, a dwarf planet larger than Pluto which is 27% more massive than Pluto and is located in the Kuiper Belt.

In 2005, Eris was officially classified as a dwarf planet by the International Astronomical Union (IAU). This classification was based on three criteria:

1. It must be in orbit around the Sun.
2. It must have enough mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape.
3. It must have cleared its neighborhood of other orbiting bodies.

The Change in Pluto’s Fate:

Eris met all these criteria while Pluto did not meet criterion number 3 above. This led to Pluto being declassified as a planet and being reclassified as a dwarf planet instead. This decision by IAU caused quite a stir among astronomers and planetary scientists who felt that this decision would cause confusion among school children who had been taught that there were nine planets in our solar system. I am sad to say that I am one of these poor children. I confirm the confusion and broken trust in our education system.

In 2006, IAU decided to reclassify Pluto as a “dwarf planet” along with Ceres, Haumea and Makemake (I did not ‘make’ that name up; apparently it’s named after the Rapa Nui God of fertility) which are also considered dwarf planets today. This decision was accepted by most astronomers and planetary scientists but some still feel that Pluto should be considered as a planet due to its size and mass which is larger than some other objects classified as dwarf planets today such as Eris and Makemake.

The Future:

What does this mean for the future of Pluto? Will it ever be considered a planet again? Will it be declassified as a planet forever? Only time will tell.

What we can say for sure is that this whole saga shows us how little we know about things that we think we know, and how feeble our ‘structured’ education system is. I am sure that telling school children, “What we learn might not be the truth” is not the best of things to do. But still, I would argue that there is a lesson to be learnt here. There may be value in teaching children the uncertainty in the knowledge imparted by the education system. This would at the very least make them more prepared to face the harsher reality than how the relative utopian educational system prepared me when I was a school-going-child.

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Further reading that might interest you: Are We Living in a Simulation.