When we were children, our teachers told us that there were nine planets in our solar system.
One day, however, we were told that the solar system went from nine planets to eight. Why was this?
It's because what was once Pluto was demoted.
1. The Background of Pluto
Discovered in 1930 by American astronomer Clyde Tombaugh, Pluto held the prestigious title of being the ninth planet in our solar system for over seven decades.
Named after the Roman god of the underworld, Pluto intrigued scientists due to its distance from the Sun and peculiar elliptical orbit.
Yet, as astronomical knowledge advanced, uncertainties arose regarding Pluto's classification as a planet.
2. Reclassification Criteria
The International Astronomical Union (IAU) is the governing body responsible for classifying celestial bodies in our solar system.
In 2006, the IAU created a new definition of what constitutes a planet. A celestial body must meet all three of the following criteria to be classified as a planet:
It must orbit the Sun.
It must be spherical due to its gravity.
It cleared other debris from orbit.
3. Pluto's Failure to Meet the Criteria
While Pluto successfully satisfied the first two criteria, it came up short in the third.
Pluto's orbit is heavily populated by numerous small celestial bodies, known as Kuiper Belt objects, which are remnants of solar system formation.
This disqualified Pluto from being categorized as a planet, as it failed to dominate its orbit.
4. The Discovery of Eris
The demotion of Pluto partially stemmed from the discovery of another celestial body in 2005, known as Eris.
Eris was found to be larger than Pluto and resided in the Kuiper Belt region.
Its discovery sparked a debate about the definition of a planet and whether Pluto should retain its planetary status.
As a result, the IAU convened to reassess how celestial bodies should be classified.
5. The Outcome: Pluto Becomes a Dwarf Planet
In 2006, the IAU reached a consensus and redefined Pluto's status.
Pluto was no longer classified as a planet but was deemed a "dwarf planet." This reclassification acknowledged the unique characteristics of Pluto and the absence of its ability to clear its orbit.
6. Scientific Advancements and Implications
The reclassification of Pluto has prompted scientists to deepen their understanding of celestial bodies within the Kuiper Belt.
The study of dwarf planets, such as Pluto and Eris, has enabled astronomers to unravel the intricacies of our solar system's past, including its formation and evolution.
Furthermore, this reclassification has emphasized the importance of precision and specificity in scientific terminology, ensuring accurate communication and fostering further research and discovery.
