Pluto, currently the most giant dwarf planet, and formerly the 9th planet, was removed as a Planet in 2006 by the International Astronomical Union. But why did they do it? Are there special Conditions for a celestial body to be classified as a planet? Here's why

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The Special Conditions for a Planet

There are 3 Conditions for a Celestial body to be declared a Planet. Pluto met 2 of these but didn't fulfill the last one. These 3 conditions are:-

1. A Planet must orbit the Sun: Pluto orbits the Sun, once in a few hundred years, So it meets this criterion

2. A Planet should be nearly round: Pluto also meets this criterion, because due to its gravity it was able to hold to a round shape, rather than objects like asteroids and other dwarf planets like Haumea

3. A Planet should clear its surroundings: Pluto didn't fulfill this criterion because It shares its neighborhood with the icy Kuiper belt, which consists of millions if icy bodies outside the orbit of Neptune. Also, it cuts the orbit of Neptune and comes near to the sun, then Neptune for a particular period in its revolution.

Image Source: AAS

Since pluto wasn't able to complete the last criterion for planets, the IAU declassified it as a planet in 2006, and also identified a few more dwarf planets, which didn't meet these criteria too.

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