The number of planets in our solar system has risen and gone down over the years. No, this is not because of the sudden emergence and absence of planets, but rather because of how they have been discovered since antiquity. Besides Earth, there were five planets that were visible to the naked eye: Mercury, Venus, Mars, Jupiter, and Saturn.

Sun and the Moon were added to their planet list by the ancient Greeks, but that idea never really caught on. In the late 1700s, Uranus’s discovery was a ground-breaking feat at the time because no one believed that there might be other planets besides the five visible. Since technology has progressed, our quest to find more planets like ours has resulted in constant observation of our universe. More recent discoveries have revealed more and more planet candidates including Ceres, Vesta, Pallas, and Juno. Which are all found in what we now know as the asteroid belt or the big asteroid belt between Mars and Jupiter’s orbit? In science textbooks in the early 1800s. They were all listed as planets. 

In the middle of the 1800s, Neptune was discovered and within just a few decades, we had quite a list of planets on our hands. At that time there wasn’t a clear distinction between the eight planets and other celestial bodies. We know today that over a 100 asteroids that were being discovered by the 1860s were finally given their own distinct classification as asteroids. These asteroids were described as objects that couldn’t be distinguished from stars and planets by the way they move across the sky. 

So even 100 or so years ago. We were ruthless and demoted planets. 

A lot of people in the world feel like Pluto has been hard done by, but Pluto has been treated just as harshly as the large asteroids. In 1930Pluto was discovered and with the excitement of finding something so large and distant as Pluto. It was quite an achievement at that time. 

In the 90s when telescopic capabilities greatly increased and other worlds were being discovered in and around the orbit of Pluto just like the discovery of the asteroid belt it quickly became apparent that there was another belt beyond the orbit of Neptune now known as the Kuiper belt. These objects are still being discovered the most famous ones being Eris, Haumea, Makemake, Gonggong, Quaoar, Sedna. But if you see the probable list of dwarf planets, seriously, they have found a lot. 

Why Pluto is important?

Pluto pushes the boundaries of our understanding of the universe nestled within the far-flung Kuiper belt at the edge of the Solar System. The dwarf planet is thought to be one of many astronomical objects left behind from the creation of the solar system. Although it has the mass similar to about half of the United States and is only about two-thirds the size of the Earth’s moon astonishingly it is one of the Kuiper belt’s largest bodies. There is something about this dwarf planet that captured the imagination of so many people and in this article, we will just find out the story behind Pluto’s demotion from a planet to a dwarf planet. And why it is important to reconsider Pluto’s status as a planet?

Pluto lies 4.67 billion miles away from Earth. If you want to contact someone on Pluto it would take about 4.5 hours for your message to reach them. 

The dwarf planet travels along a highly elliptical orbit that brings it inside Neptune’s orbit for 20 years out of every 248 years. Pluto’s revolution brings it closer to the Sun than Neptune. The last time this happened was from 1979 to 1999. It won’t happen again until 2227. Pluto, like the planet Uranus, rotates on its side, with its axis tilting around 120 degrees. Even when the dwarf planet is closest to the Sun it records a temperature of minus 369 degrees Fahrenheit. You would still be freezing out there. This distant world has an atmosphere, but don’t expect to breathe in it. The atmosphere there is very thin and weak, owing to the low gravity of the dwarf planet, which is just around 6% of Earth’s atmosphere consisting of nitrogen and methane gases plus the red hydrocarbon particles that scatter sunlight. Pluto’s atmosphere can freeze and fall back on its surface as snow. This varying geography is affected by the existence of weather cycles or an atmosphere

When Pluto passes closer to the Sun, ice on its surface slowly warms and sublimes near the surface (“evaporate” from solid to gas) to create a thin, mainly nitrogen-rich atmosphere. The gasses cool and refreeze as it travels away from the sun. As Pluto moves farther from the Sun, the atmosphere vanishes. 

The surface of Pluto has large differences in brightness meaning the dwarf planet has a varied landscape. The top surface of the dwarf planet is composed of rock material and other forms of ice such as frozen carbon monoxide, methane, and nitrogen. These frozen gasses surround Pluto’s about six point four million square miles of surface area, the rocky terrain is just like Earth’s and similar geological structures like polar ice caps, valley, planes, and craters can be found on its surface. It also has surface glaciers composed of frozen ice and liquid water that keep Giant mountains floating. The mountains there are made of water Ice. 

But how much would you way there? Well, if you weighed 150 pounds on Earth you would weigh only 10 pounds in Pluto. 

Floating high above the dwarf planet’s atmosphere are its five moons. The largest Charon is about half the size of Pluto and other moons Nix, Hydra, Kerberos, and Styx are much smaller. 

It was discovered by the mid-1800s, but Pluto was not spotted until 1930. Pluto named after the Roman god of the underworld was considered the ninth planet. No one minded it being called a planet but then in the 1970s, Pluto was discovered to be a lot tinier than expected. 

Eventually, in 2006 Pluto lost the status of being a planet at the time worlds similar to Pluto were being discovered deeper in the Kuiper belt. 

So, Pluto was reclassified and arguably demoted from being a true planet to a dwarf planet. 

But, new studies and pressure from the scientific community are pressing the IAU to reconsider Plutus’s status and with this many, more dwarf planets can actually be called planets. Pluto is as interesting and elusive as the other 8 planets and reconsidering it will ignite more explorations in the Kuiper belt and beyond. 

Discovery of Pluto

It was astronomer Clyde Tombaugh of America who discovered Pluto in 1930. But previous to the discovery another astronomer called Percival Lowell had been attempting to locate it for over a decade. In the late 19th and early 20th centuries, astronomical measurements showed wobbles in the orbits of Uranus and Neptune. Lowell believed these wobbles were caused by the gravitational pull of a ninth planet. 

He tried between 1906 and 1916, but his endeavors were unsuccessful. It wasn’t until Tombaugh used a modern optical method where new technique involved photographic plates paired with a blink microscope to scan for traces of moving objects in the sky was developed. 

He took photos of the same section of the night sky but on two different dates, he could measure the photographic plates to see how the location of an object had changed. Finally, Tombaugh on February 18, 1930, discovered a brand new planet that was called Pluto which was moving in an orbit around the sun. 

Why Pluto is not a planet?

It was classified as a planet although within a few decades it was discovered that it didn’t follow the conventions of a traditional Planet the planets. We know have circular orbits that are line roughly with the plane of the solar system. Pluto on the other hand orbits at an angle to the solar system and its orbit is so elliptical that at some point during its revolution around the sun, it can move really far away. 

The IAU finally classified a planet as a celestial object that:

• Is in orbit around the sun 
• Has a nearly round shape 
• Has cleared the neighborhood around its orbit. 

So although Pluto satisfies the first two conditions, because it lies in the Kuiper belt it is not cleared its orbit and thus is not regarded as a planet. It is instead known as a dwarf planet, which is almost the same except it’s not massive enough to have cleared its orbit. 

But curiosity to know what Pluto looks like took us near to this distant planet and we got a glimpse of this unique and interesting world. 

Closing notes

There’s been a huge debate in the public and in the scientific community about the fate of dwarf planets, especially Pluto. 

The IAU says a planet has to be a sun orbiting body that is massive enough to be round and will have cleared its orbit meaning nothing gets in the way as it goes around the Sun. This definition keeps asteroids, comets, and moons from being classifieds as planets, but it excludes some smaller bodies from being called a planet, which is why Pluto is now called a dwarf planet. 

Today, our solar system has eight planets, but it also has five dwarf planets as well. Ceres, Pluto, Eris Makemake, and Haumea. Although, the current definition actually upgraded four celestial bodies and yet nobody talks about it. Now, we have 13 planets in our solar system. 

The thing is dwarf planets aren’t technically planets though. But, some NASA scientists have proposed to reclassify planets and if it’s done we will have at least 100 new planets. 

That’s it. 

That means Pluto will be a planet again, which is awesome, but under this interpretation, it will also allow friends Ceres, Eris, Makemake, and Haumea to join the club of planets as well as 97 other objects. Our solar system will have 110 planets new to us.

Firstly, there are many explanations why scientists think about this, the existing interpretation states that all planets will circle our sun.

This means although over a thousand exoplanets have been discovered in the universe still there will be only planets eight real planets. As these planets are orbiting other stars and are not orbiting the Sun, so they are not technically planets.

Yes. It’s obscure. This is science. We’re talking about obscurity which is part of the game. On the other hand, both definitions do count being round is important because it keeps asteroids out of the planetary club, but the brightest of brains already pointing out the Moon. It is round and yes under the definition. Our moon would be a planet as would all the round moons of Jupiter and Saturn and elsewhere defining planets in this way. The IAU definition of classifying planets is ‘flawed’ according to many scientists. 

Not only because Pluto has been demoted, but it also seems unfair to other celestial bodies that are as unique and interesting as Saturn or Venus. If we continue to consider Ceres, Eris, Makemake, and Haumea as planets, the researchers expect that there will be further explorations to find out more about such dwarf planets.

If these celestial bodies are classified as planets astronomers would want to observe them. One of the lead authors on this paper is Alan Stern who is an outspoken critic of the 2006 IAU reclassification. 

Thanks to the amazing data scientists get from Pluto plus the things we ‘re discovering about moons like Europa, Enceladus, Titan, Io, and Ganymede, this controversy has been reignited.

For instance, Pluto is no longer considered to be a boring icy rock zipping past the sun but sometimes closer than Neptune. We know it has complex geological processes that may hide nitrogen subterranean oceans and glaciers, a thin atmosphere and its solar planetary interaction is unique and unlike the pompous planets like Neptune and Uranus in our solar system, but does being more interesting than we thought to warrant Pluto’s readmission to the planet club?

If it does, then there is great news. As we will have more celestial bodies classified properly, there will be more interest in knowing about them. It will fuel the upcoming generation to take up the universe as a field of study and solve many of its riddles. We want a fresh perspective for sure and reclassification of the planet can certainly ignite that fire.