Not a Planet anymore: Pluto - Erakina

In my 4th or 5th grade, I heard the biggest news from the scientific world that makes the content in our textbooks alter. From now on (2006), there will be only eight planets in the solar system as the smallest one, Pluto, has been removed. I thought I knew why it’d been done without realizing that I was wrong until this moment when I started reading about Pluto for writing this blog.

Planets in sequential order away from the sun

Discovery and Description:

It could be said it is the latest planet discovered in the year 1930. Even though Percivall Lowell started the work in 1906 under the name of Planet-X, Clyde Tombaugh, a 23 years old young man, discovered the planet’s existence after Lowell’s death. Beyond Neptune, the ninth planet from the Sun consists of ice and rocks, and its atmosphere has traces of Methane, Carbon Monoxide, and Nitrogen on the ice coatings. It takes 5.5 hours for the Sun’s light to reach its surface compared to the Earth, which is only 8 minutes, 20 seconds, and requires 247.68 years to complete one rotation around the Sun. The temperature on the planet is frigid, holding at -228 degrees Centigrade.

Space expeditions to Pluto:

The farthest planet Pluto took longer to be discovered, and it was difficult to study its surface and Moons. NASA launched a New Horizons mission in 2006 which was the first probe launched to understand Pluto, its Moons, and any other significant planetoids outside the Kuiper belt (a dense layer of icy objects beyond which exists, Pluto). After a long journey through inter-planetary spaces passing closely through Jupiter, it finally reached the atmospheres of Pluto by 2015. The icy structures on the surface of pluto pictures were retrieved from this probe and helped discover moons of Pluto.

Pluto and Its Moons:

There are five moons for Pluto – Charon, largest, Nix, Hydra (discovered in 2005), Kerberos, and Styx found with the help of New Horizons Mission.

Charon is half of the diameter of the planet Pluto, which was found with a reddish-brown ice cap towards the North Pole. The organic macromolecules, tholins emitting Methane, Nitrogen, and other gases, prove the chances of the emergence of life. Charon has a synchronous rotation with the planet means – both of them move simultaneously, such that one couldn’t view their Moon Charon when living on the opposite end of the planet.

The five Moons of the Pluto

Deportation from the solar system:

In 2006, the International Astronomical Union redefined the Planets’ definition, disbarred the planet Pluto from the list, and categorized it as a Dwarf planet. For the gigantic masses to be called planets – criteria (3) required are – entity orbiting around the Sun, possessing its gravity to maintain its shape, and lastly must have clear its neighbourhood around its orbit.

After satisfying the first two rules, Pluto couldn’t fulfil this condition of clearing neighborhood, means the gravitational force exerted by it couldn’t suffice to clear its way of the orbit. Also, its orbit overlaps twice with the Neptune when rotating around the Sun and is under the influence of Neptune’s gravitational force.

Dwarf planets:


The planetary material that couldn’t clear their surrounding masses. Cemers (the only Dwarf planet within the asteroid belt- between Mars and Jupiter), Pluto, Haumea (elongated), Makemake, Eris (outermost one).

By – Anusha Velamuri

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