Pluto: The Planet That Lost its Title

As we all know Pluto is a planet that lost its title of being a planet. I remember when I was a kid, studying in 6th grade, my geography teacher used to make us memorize the names of planets.

He gave us a Mnemonic to memorize the names of the planets and that was like this, “My Very Educated Mother Just Served Us Nine Pizzas.” I memorize that very well.

By the time, when I got admission to my graduation, scientists ate those pizzas. Now the same mnemonic for the new generation is like ( My Very Educated Mother Just Served Us Nine). This happened because the pluto lost his title of being a planet in 2006. Now, it is being considered a dwarf planet.

I hope you must have got my point. Yes! Today I am gonna tell you everything about the planet that lost its title.

Discovery of the Dwarf

Urbain Le Verrier

If we talk about the discovery of Pluto, it can be said to be started in 1840, when Urbain Le Verrier used Newtonian mechanics to predict the Planet Neptune after analyzing perturbations in the orbit of Uranus.

Subsequent observations of Neptune led astronomers to believe that Uranus’s orbit is being disturbed not only by Neptune but some other planet also.

Percival Lowell

In 1906, Percival Lowell, the founder of Lowell Observatory in Flagstaff, Arizona, started an extensive project. The purpose of that project was to search the ninth planet. He called it “Planet X”.

By 1909, Lowell and William H. Pickering had suggested many possible celestial coordinates for such a planet. Lowell and his observatory continued his search until his death in 1916, but got nothing.

The director of Lowell Observatory, Vesto Melvin Slipher gave the task of finding the planet X to a 23-years old Clyde Tombaugh.

Clyde Tombaugh

Tombaugh’s task was to photographs of night sky and arrange them in an order. Then examine those photographs and determine the shift in any object’s movement.

He used a blink comparator and rapidly shifted back and forth between views of each of the photos to create the illusion of movement of any objects that had changed position or appearance between photographs.

After nearly a year of searching, on 18th Feb 1930, he discovered a possible moving object on his plates taken on 23rd and 29th Jan. News of the discovery sent to the Harvard College Observatory on March 13, 1930.


The first and only spacecraft that sent to pluto to explore it, was The New Horizon spacecraft in 2015. It was launched in 2006, and made its closest approach to Pluto on July 14, 2015, after a 3,462 days journey across the Solar System.

Scientific observations of Pluto started five months before the closest approach. It continued for at least a month after the encounter. The spacecraft has a remote sensing package equipped with imaging instrument and radio science investigation tool.

The scientific purpose of the New Horizon was to characterize the geology and morphology of Pluto and its moon Charon. The last bit of data was received from the New Horizon on 25th October 2016.


Dwarf planet Pluto is a member of a group of objects called Kuiper-Belt. This Kuiper Belt is a disc-like zone beyond the orbit of Neptune.

This inaccessible domain is populated with a large number of scaled-down frosty universes. It was framed right off the bat throughout the entire existence of our close planetary system about 4.5 billion years prior.

These icy, rocky bodies are known as Kuiper Belt objects, transneptunian objects, or plutoids.


Pluto is almost two-thirds of the diameter of Earth’s moon. Most probably it has a rocky core surrounded by a layer of water ice.

Interesting ices like methane and nitrogen frost coat it’s surface. Due to its low density, Pluto has a mass of about one-sixth that of Earth’s moon.

Size and Distance

Pluto has a radius of 1,151 kilometers, which makes it about 1/6 the width of Earth. If we assume the Earth to be the size of a nickel, Pluto would be almost as big as a popcorn kernel.

From a mean distance of 5.9 billion kilometers, Pluto is 39 astronomical units distant from the sun. One astronomical unit (abbreviated as AU), is the distance from the sun to Earth.

From this distance, sunlight takes 5.5 hours to travel from the sun to Pluto.

If you somehow managed to remain on the outside of Pluto around early afternoon. The sun would be 1/900 the splendor it is here on Earth, or around multiple times as brilliant as our full moon.

There is a moment every day closer to sunset here on Earth when the light has the same brightness as midday on Pluto. This time on Earth is called “Pluto Time”. Find out the next “Pluto time” where you live.

Orbit and Rotation

Pluto’s circle around the sun is strangely contrasted with the planets: it’s both curved and tilted. Pluto’s 248-year-long, the oval-molded circle can accept it to the extent 49.3 galactic units (AU) from the sun, and as close as 30 AU.

One AU is the mean separation among Earth and the sun: around 93 million miles or 150 million kilometers. But by and large, Pluto is 3.7 billion miles (5.9 billion kilometers) away from the sun, or 39 AU.

From 1979 to 1999, Pluto was near perihelion, when it is nearest to the sun. During this time, Pluto was actually nearer to the sun than Neptune.

One day on Pluto takes around 153 hours. Its pivot of revolution is tilted 57 degrees as for the plane of its circle around the sun, so it turns nearly on its side.

Pluto additionally shows a retrograde revolution; turning from east to west like Venus and Uranus.


Pluto’s surface is described by mountains, valleys, fields, and holes. The temperature on Pluto can be as cold as – 226 to – 240 degrees Celsius.

Pluto’s mountains can be as tall as 6,500 to 9,800 feet and are big blocks of water ice. Sometimes with a coating of frozen gases such as methane.

What’s more, long troughs and valleys up to 370 miles (600 kilometers) add to the intriguing highlights of this faraway smaller person planet.

Craters as large as 260 kilometers in diameter dot some of the landscape on Pluto, with some clear signs of erosion and filling. This advises tectonic forces are slowly resurfacing Pluto.

The most unmistakable fields saw on Pluto have all the earmarks of being made of solidified nitrogen gas and show no holes. These fields do show structures proposing convection (masses of material coursing all over).


Pluto has a slender, questionable climate that extends when it comes nearer to the sun and crumples as it moves more remote away—like a comet. The main constituent is molecular nitrogen, though molecules of methane and carbon monoxide have also been detected.

When Pluto is near to the sun, its surface ices directly changes from solid to gas or sublimate and rise to temporarily form a thin atmosphere. Pluto’s very low gravity (about six percent of Earth’s) causes the atmosphere to be much more extended in altitude than our planet’s atmosphere.

Pluto becomes colder during the course of each year when it is orbiting far away from the sun. During this time, most of the planet’s atmosphere might freeze and fall like snow to the surface.


It is not clear whether Pluto has a magnetic field, but its small size and slow rotation suggest little or negligible.


As per the knowledge now, there are no rings around Pluto.


Till now it has five known moons: Charon, Nix, Hydra, Kerberos and Styx. This moon system might have been formed by an encounter between Pluto and another same-sized body early days in the history of the solar system.

Charon is the biggest moons in its system. It is around half the size of Pluto itself. This makes Charon the largest satellite relative to the planet it orbits in our solar system.

It orbits Pluto at a distance of only 19,640 kilometers. For comparison, our moon is 20 times away from Earth. Pluto and Charon are many times referred to as a double planet.

Charon takes 153 hours to orbit pluto —the same time it takes Pluto to complete one orbit. This clearly means Charon neither rises nor sets, but overlaps over the same spot on Pluto’s surface. Charon is tidally locked with pluto means it always faces the same side.

The other four moons of Pluto are much smaller, less than 160 kilometers wide. They’re also irregularly shaped, not spherical like Charon.

These moons are not tidally locked with pluto. They all spin and never keep the same face towards Pluto.

Potential for Life

Due to its extreme cold surface, it seems unlikely that life could nurture there. At such cold temperatures, water, the most vital part of life as we know it, is essentially frozen and are rock-like.

Pluto’s interior is warmer, however, and some think there could even be an ocean deep inside.

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