To answer this question, we first have to think about how we actually define what a planet is. In space we have different ways of characterizing the astronomical bodies, and of differentiating them from one another.
Is there a way to define what a planet it?
In science, numbers play the largest role because they are exact and everyone can understand them equally across the world, making them universal as a defining language.
But we still use words constantly to communicate science, so it follows that the definitions for these astronomical bodies are also in word format.
The wordy definition states that a planet is a celestial body that moves in an orbit around a star. Hence, earth is a planet, but the moon is not, since it orbits us.
Pluto orbits the sun!
Yes, Pluto does orbit the sun, just like Earth. This is where the numbers of the definition come along to make this answer a little more complicated.
This is why words alone cannot be the final definition of what each celestial body is. Just like a red dwarf star can technically be considered a planet, Pluto can technically not be considered one.
What is the math then?
Pluto is a rocky object in space that orbits our sun and has a radius of 1153 km and a mass of 1.3 x 1022 kg. These are the facts since they are the numbers and math of the astronomical object that is Pluto.
So, it is easier to call Pluto a planet or even an asteroid than to call it a rocky giant that orbits the sun.
What is the debate then?
The main debate that surrounds Pluto is obviously whether or not it fits the ‘planet’ characteristics. But this only a debate that takes place linguistically.
The math and numbers of the debate will never change, so there is no change in that area. But over time, verbal science and opinions can change. Our wording of the definition of what makes a planet can change.
These debates using language as opposed to numbers are all focused on using the right words and not adding more confusion to the question.
But what do I call Pluto then?
Technically, you can call Pluto whatever you want: planet, asteroid, great big rock that orbits the sun at the furthest point in the solar system.
But, if you are in a debate talking about what Pluto is, you will probably want to back it up with definitions and facts. One argument that Pluto is a planet is that it orbits a star and is a celestial body.
But one argument against it being a planet is that it is too small. But be aware that certain names can cause people to be confused, since some people will have differing definitions for the different names of objects in space.
Some facts about Pluto:
Here we have compiled some facts about Pluto, so that you can confidently debate this topic with friends, or even scientists and astronomers.
- Pluto does orbit the sun, just like planets, asteroids and even comets. The same sun that Earth orbits, since it is in the same solar system.
- Pluto has a relatively spherical shape, making it more like a planet than an asteroid or comet. This is a point in favor of it being a planet.
- Pluto even has its own moons like other planets, Earth and Jupiter included. Asteroids and comets do not have moons in their orbit.
- Pluto’s orbit around the sun mimics a comet, in that it is irregular, this is unlike the patterns of planet orbits.
- Pluto has a similar size and even shape to some of the asteroids that are beyond Neptune. This is a point in favor for Pluto not being a planet.
- Pluto has not gravitationally cleared its surroundings of other bodies like a planet would. Making it more like an asteroid.
Even though you could call Pluto a planet since you can call it whatever you choose to, sometimes this could be misleading. If you call Pluto a planet, someone might think you mean that it has a regular orbit around the sun like Earth, but it does not.
But if you call it an asteroid, people will think Pluto is not spherical, which it is.
What is the answer then?
In 2006, astronomers came up with a new classification to avoid this exact confusion. Pluto was considered a dwarf planet. It still is today in 2020. We consider it to be a dwarf planet that is in the Kuiper Belt just past Neptune.
So, it is neither a planet nor an asteroid. The reason there was so much debate surrounding Pluto is simply because we did not know much about it. Science is always developing and changing, making way for new definitions and classifications.