DEMOTED?! 😥 Why Isn't Pluto A Planet Anymore? | COLOSSAL QUESTIONS

Summary

This script narrates the intriguing tale of Pluto, once considered the ninth planet in our solar system, but later reclassified as a dwarf planet. It explores the historical discovery of planets, from ancient astronomers identifying Mercury to Neptune, and the 20th-century discovery of Pluto. The crux lies in the 2006 definition of a planet, which Pluto fails to meet due to its inability to clear its orbital path of other objects. The script humorously concludes that Pluto, being so distant, might not even be aware of its demotion.

Takeaways

• 🌌 The script begins with the story of Pluto, once considered the farthest, smallest, and coldest planet in the solar system, but later reclassified as a dwarf planet.
• 🌟 Ancient Babylonian astronomers identified the first five planets: Mercury, Venus, Mars, Jupiter, and Saturn, around 3000 to 4000 years ago.
• 🌍 The concept of Earth being a planet dates back to ancient Greece, with the term 'Planataz' meaning 'Wanderers', indicating the planets' unique paths in the sky.
• 🔭 The discovery of Uranus in 1781 by Sir William Herschel marked the next addition to the known planets in our solar system.
• 🌊 Neptune was officially discovered in 1846 by Johann Galle, though it was observed by Galileo in 1612 but was mistaken for a star.
• 🚀 Pluto was discovered in 1930 and was considered the ninth planet of the solar system until the early 2000s.
• 🔍 The definition of a planet was revisited in the early 2000s due to the discovery of many Pluto-sized objects in the solar system.
• 🌐 In 2006, the International Astronomical Union established three criteria for an object to be considered a planet: orbiting the sun, being spherical due to its own gravity, and clearing its orbit of other objects.
• 💥 Pluto failed to meet the third criterion, as it does not have enough gravitational influence to clear its orbit of other debris, leading to its reclassification as a dwarf planet.
• 👨‍🔬 The reclassification of Pluto was a result of a more precise definition of what constitutes a planet, reflecting advancements in astronomical knowledge and technology.
• 👋 Despite the reclassification, the script humorously suggests that Pluto, being so far away, might not even be aware of its change in status.

Q & A

Why was Pluto reclassified from a planet to a dwarf planet?

Pluto was reclassified because it does not meet the third criterion for being a planet, which is to clear the neighborhood of its orbit. It is not massive enough to have cleared other objects from its orbital path.

What is the historical significance of the term 'planet' and its origin?

The term 'planet' originates from the ancient Greeks, who called them 'Planataz,' meaning 'Wanderers,' as they moved on their own paths through the sky, unlike stars.

How many planets were recognized in the solar system before Pluto's discovery?

Before Pluto's discovery in 1930, there were eight recognized planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

What was the first planet discovered by humans, and when was it identified?

The first planets discovered by humans were Mercury, Venus, Mars, Jupiter, and Saturn by ancient Babylonian astronomers between 3000 and 4000 years ago.

Who discovered Uranus, and what was initially mistaken for a comet?

Uranus was discovered by Sir William Herschel in 1781, who initially mistook it for a comet.

When was Neptune officially discovered, and by whom?

Neptune was officially discovered by Johann Galle in 1846.

Why was the definition of a planet revisited in the early 2000s?

The definition of a planet was revisited due to the discovery of many Pluto-sized objects, which raised the question of whether they should also be considered planets.

What are the three basic criteria for an object to be considered a planet?

The three criteria are: 1) It must orbit the sun, 2) It must be large enough for its own gravity to mold it into a spherical shape, and 3) It must clear the neighborhood of its orbit.

How many dwarf planets are recognized in the solar system as of 2023?

As of 2023, there are five recognized dwarf planets in the solar system: Pluto, Ceres, Eris, Haumea, and Makemake.

What is the significance of the year 2006 in the context of Pluto's classification?

In 2006, the International Astronomical Union (IAU) defined the criteria for a celestial body to be considered a planet, which led to Pluto's reclassification as a dwarf planet.

How does the script describe the public's perception of Pluto's reclassification?

The script describes the public's perception as empathetic, suggesting not to shed too many tears for poor Pluto, as it is still floating far out in the solar system and may not even be aware of its reclassification.

Outlines

00:00

🌌 The Downfall of Pluto: From Planet to Dwarf

This paragraph delves into the historical journey of Pluto's status within our solar system. Initially considered the farthest, smallest, and coldest planet, Pluto was demoted to a dwarf planet due to a change in the scientific definition of a planet in the early 2000s. The narrative begins with ancient observations of celestial bodies and the gradual recognition of Earth as a planet among others. It highlights the discovery of Uranus and Neptune and culminates with Pluto's discovery in 1930, which expanded our solar system to nine planets. The paragraph concludes with the revelation that Pluto's inability to meet the new criteria for a planet—specifically, clearing its orbit of other objects—led to its reclassification.

05:02

🚀 Redefining Planetary Status: Pluto's Reclassification

The second paragraph focuses on the criteria established by planetary scientists in 2006 to define what constitutes a planet. It explains that while Pluto meets the first two criteria of orbiting the sun and having a spherical shape due to its gravity, it fails the third: clearing its orbit of other objects. This inability leads to Pluto's reclassification as a dwarf planet, reducing the number of recognized planets in our solar system to eight. The paragraph also mentions other dwarf planets such as Ceres, Eris, Haumea, and Makemake, and ends on a light-hearted note, suggesting that Pluto, being so distant, might not even be aware of its change in status.

Keywords

💡Pluto

Pluto is the central subject of the video, once considered the ninth planet in our solar system but later reclassified as a dwarf planet. The script discusses its historical significance and the reasons for its reclassification, highlighting its small size and inability to clear its orbit of other objects. The term 'Pluto' is used to evoke a sense of curiosity and to explore the changing definitions in astronomy.

💡Dwarf planet

A dwarf planet is a celestial body that orbits the Sun, is massive enough for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, has not cleared the neighborhood around its orbit, and is not a satellite (moon) of another object. The script uses 'dwarf planet' to explain Pluto's current classification and distinguishes it from the eight recognized planets.

💡Solar system

The solar system refers to the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or as moons. In the script, the solar system is the context for discussing the planets and Pluto, emphasizing the dynamic nature of celestial bodies and their discovery throughout history.

💡Planet

A planet is a celestial body that orbits a star, is massive enough to be nearly round, and has cleared its orbit of other debris. The script uses the term 'planet' to contrast with 'dwarf planet' and to illustrate the criteria established by astronomers in 2006 for what constitutes a planet, which led to Pluto's reclassification.

💡Astronomers

Astronomers are scientists who study celestial objects, the physics, chemistry, and evolution of such objects, and phenomena that originate outside the atmosphere of Earth. In the script, astronomers are credited with the discovery of planets and the redefinition of what constitutes a planet, which directly impacts Pluto's status.

💡Orbit

Orbit refers to the path that an object takes around another object in space, due to the force of gravity. The script mentions that for an object to be considered a planet, it must orbit the Sun, which is a key criterion for Pluto and other celestial bodies.

💡Hydrostatic equilibrium

Hydrostatic equilibrium is a state of balance where the inward force of gravity is precisely counterbalanced by the outward pressure of the material within a celestial body, resulting in a nearly round shape. The script uses this term to describe the second criterion for an object to be classified as a planet, which Pluto meets.

💡Clearing the neighborhood

Clearing the neighborhood is the third and most critical criterion for an object to be considered a planet, meaning it must have enough gravitational influence to clear its orbit of other debris and smaller objects. The script explains that Pluto fails to meet this criterion, leading to its reclassification as a dwarf planet.

💡Ceres, Eris, Haumea, Makemake

These are the four other recognized dwarf planets in our solar system, in addition to Pluto. The script mentions them to provide context and comparison for Pluto's status, emphasizing the unique characteristics that define dwarf planets.

💡2006 reclassification

The 2006 reclassification refers to the decision by the International Astronomical Union (IAU) to redefine the criteria for what constitutes a planet, which resulted in Pluto's reclassification as a dwarf planet. The script uses this event to illustrate the ongoing evolution of scientific understanding and classification in astronomy.

💡Stargazing

Stargazing is the practice of observing the night sky, typically with the naked eye, for recreational or scientific purposes. The script uses 'stargazing' to describe the historical method by which ancient civilizations discovered celestial bodies, setting the stage for the discovery and classification of planets.

Highlights

Pluto was once considered the farthest, smallest, and coldest planet in the solar system.

Pluto was reclassified from a planet to a dwarf planet due to changes in the scientific definition of a planet.

Ancient Babylonian astronomers identified the first five planets between 3000 and 4000 years ago.

The term 'planet' comes from the ancient Greeks, who called them 'Planataz', meaning 'Wanderers'.

Uranus was discovered in 1781 by Sir William Herschel, initially mistaken for a comet.

Neptune was officially discovered in 1846 by Johann Galle, after being observed by Galileo in 1612.

Pluto was discovered in 1930, completing the then-known solar system of nine planets.

The definition of a planet was revisited in the early 2000s due to the discovery of many Pluto-sized objects.

A planet must orbit the sun, be spherical due to its gravity, and clear its orbit of other objects.

Pluto failed to meet the third criteria of clearing its orbit, leading to its reclassification as a dwarf planet.

As of 2023, there are five recognized dwarf planets: Pluto, Ceres, Eris, Haumea, and Makemake.

Pluto's reclassification was due to its insufficient size to clear its orbit of other objects.

The story of Pluto's reclassification highlights the evolving nature of scientific definitions and discoveries.

The reclassification of Pluto has led to a better understanding of celestial bodies in our solar system.

The process of defining a planet involves a combination of historical context and modern scientific criteria.

The story of Pluto serves as a reminder of the dynamic nature of astronomical discoveries and classifications.

Transcripts

SPEAKER: Have you ever heard the sad story

of Pluto, the poor little dwarf planet that was?

For decades, it was considered the farthest, smallest,

and coldest planet in the solar system

until it was kicked out of the group.

Talk about cold.

So what on Earth happened?

Why isn't Pluto considered a planet anymore?

Let's find out on today's episode of Colossal Questions.

Did you know that thousands of years

ago, people didn't have every form of entertainment

imaginable in front of their eyes at all times.

Yep, they had to sit down, relax, and just look up.

Sounds boring, right?

Maybe at first.

But once the sun went down, people

started to notice that there were lots of interesting things

up in the night sky.

Not just pretty little stars, but patterns, colors,

and objects of different sizes that

seemed to move differently than the rest of the stars blinking

in the sky.

People started noticing these strange little balls

of colorful light.

Bulbs that would ultimately be known as the planets

in our solar system.

But finding each of the planets in our solar system

took some time and some stargazing.

Funny enough, Earth wasn't actually

the first planet we discovered.

We lived here all along.

So first we had to look up and discover other planets

in the sky before we realized we were on one of them.

Ancient Babylonian astronomers, I

did mercury, Venus, Mars, Jupiter, and Saturn

sometime between 3000 and 4000 years ago.

That's a really long time ago.

The idea of the Earth being one of the planets

in the solar system dates back to at least ancient

Greece around 2,300 years ago.

The ancient Greeks called them Planataz,

which is where we get the word in English.

It means Wanderers, since the planets forged their own paths

through the sky.

Over the next 2,000 or so years, humans mostly

found the occasional meteor, asteroid, or moon floating

around in the solar system.

It wasn't until 1781 that the next planet was discovered.

Uranus, an astronomer named Sir William Herschel first

mistook the seventh planet from the sun for a comet.

Fast forward 65 more years to 1846,

and Neptune is officially discovered by Johann Galle,

the eighth planet from the sun.

Fun fact.

It was actually first spotted by Galileo

all the way back in 1612, but he mistook it for a star.

Whoops.

And finally, of course, there was Pluto, the poor dwarf

planet that used to be a planet was discovered in 1930.

This gave us a solar system of nine planets--

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,

Neptune, and last but not least, Pluto.

It was the coldest, furthest, and smallest planet

of the group, even smaller than the Earth's moon.

Pluto was a fixture in our solar system for more than 70 years.

Just minding its own business out in the furthest

reaches of our solar system doing its thing.

So what changed?

Well, Pluto itself didn't actually change at all.

What did change was the actual definition of a planet

back in the early 2000s.

You see, up to that point, the scientific definition

of a planet was surprisingly loose.

There was no real criteria to decide what officially made

something a planet.

Up to that point, astronomers had loosely

grouped all the planets together since they all

seemed to move on their own paths through the sky,

unlike stars.

For a long time, this super loose definition

wasn't much of a problem.

But that started to change as more and more Pluto-sized

planetoids were being discovered.

In the past, it would take hundreds,

sometimes thousands of years for humans to notice a new planet.

But with modern technology, we started finding

lots of new things quickly.

So quickly that we were forced to ask,

should all these new discoveries be considered planets too?

After all, they weren't much different from Pluto.

And if Pluto was a planet, then without an official definition,

they probably should be planets too.

So in 2006, some of the top planetary scientists

got together to try and define a planet once and for all.

They came back with just three basic things

an object needed in order to be considered a planet.

First, it needed to orbit the sun.

For Pluto, that's a check.

Second, a planet must be large enough so

that its own gravity molded it into a spherical shape.

Another check for little round Pluto.

But the third condition for planethood

is where Pluto ran into a problem.

A planet must clear the neighborhood of its orbit.

In other words, as a planet travels,

its gravity should clear the space

around it of other objects.

Some objects might crash into the surface,

others might start orbiting the planet and become moons.

Unfortunately for Pluto, it simply

isn't even close to big enough to clear everything

in its path.

So astronomers decided to officially reclassify

the former ninth planet Pluto as a dwarf planet,

leaving us with only eight planets in our solar system.

As of 2023, there are just four other dwarf planets

in addition to Pluto--

Ceres, Eris, Haumea, and Makemake.

So why isn't Pluto a planet anymore?

At the end of the day, the little planet

that could in the far reaches of the solar system

simply isn't big enough to be an actual planet, at least not

based on the current definition.

It might sound cold.

But honestly, it's nothing new for that frozen bowl of ice.

So don't shed too many tears for poor Pluto.

I mean, it's floating so far out there,

chances are it hasn't even gotten the memo yet.