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Why Pluto Should Be A Planet

Updated on July 15, 2015

Pluto, the real deal, up close and personal!

The images of Pluto and New Horizons are provided by NASA, used with permission. Nice to meet you Pluto!
Credit: NASA, ESA and G. Bacon (STScI)
Credit: NASA, ESA and G. Bacon (STScI) | Source

The Case for Pluto

I first dreamed of being an astronomer in the fourth grade, when I chose astronomy as my topic for the science fair at my elementary school that year. One of the basic tenets any aspiring astronomer needed to know was the names of the planets, in order.










That's what everyone said, and that's what everyone had said since the last planet - Pluto - had been discovered way back in 1930.

That is, until, 2006, when the astronomical community passed rules regarding what traits a celestial body must have to be considered a full-fledged planet.

According to, those traits include:

  • It needs to be in orbit around the Sun – Yes, so maybe Pluto is a planet.
  • It needs to have enough gravity to pull itself into a spherical shape – Pluto…check
  • It needs to have “cleared the neighborhood” of its orbit – Uh oh. Here’s the rule breaker. According to this, Pluto is not a planet.

Therein lies the rub. After 76 years of calling Pluto a planet, the International Astronomical Union had decided to reclassify Pluto a Dwarf Planet.

Here's the problem. What does "Cleared the neighborhood" mean? One interesting detail I remember learning during my research for the science fair is that because Pluto has an irregular orbit, for a prolonged period of time, after the orbits of Pluto and its much larger neighbor Neptune intersect, Neptune was actually further away from the Sun than Pluto was.

So if the reason why astronomers feel that Pluto should not be considered a planet is because it has not "cleared the neighborhood," why should we feel that Neptune is a planet either? Obviously, if little old Pluto continues to intersect the orbit of Neptune every few hundred years, Neptune hasn't done enough to clear the neighborhood.

In fact, another interesting detail I remember about Pluto is that, at least in the 1970s, one of the ideas about Pluto is that it was once a moon of Neptune, but somehow it was able to escape the orbit of Neptune and establish its own (highly irregular) orbit around the Sun.

If Neptune was so weak that it could not keep this prodigal child in check, why should we take Neptune seriously as a planet? Could it be because Neptune is much bigger than Pluto?

I think we're getting warm here. The problem with Pluto is that it's just too small, and that's what got the IAU's panties in a bunch. Something that small just shouldn't be a planet. Of course, they couldn't just come out and say that, so they came up with this other idea about clearing the neighborhood (a nice, vague, easily debatable term).

Here's another interesting tidbit. Did you know that every year, our own Moon (which some in the astronomical community refer to as Luna) is getting further and further away from us? Did you know that the mass of the Earth in relation to the Moon is close enough that some astronomers refer to this as a binary planetary system with two planets in the same orbit around the Sun? Does that sound like Earth has "cleared the neighborhood?"

Interestingly enough, astronomers predict that in millions or billions of years, the Moon will stray far enough away from the Earth that the Moon will escape from our grasp and become a planet in its own right. But do you think the astronomers in the IAU will ever conclude that our precious Earth should not be a planet? I mean, look at it. Earth is tiny compared with the likes of Jupiter, Saturn, Uranus and Neptune, and if Neptune is so wimpy that it can't even keep tiny little Pluto in line, a mere dwarf planet, why should we presume to call our own home a planet?

Maybe in the broad scheme of things, it doesn't matter much whether we call ourselves a planet, a dwarf planet, or a piece of space junk. So in that regard, doesn't the IAU have more important things to do with its time than debate about whether Pluto should be a planet?


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    • Silver Poet profile image


      I think Pluto should be a planet. I also think they shouldn't mess up the jingles people make to remember the planets, such as "My Very Eager Mother Just Serve Up Nine Pies."

    • crashcromwell profile image

      crashcromwell 6 years ago from Florida

      I agree! I saw a website last night that said they would need to change the jingle to something like "My Very Eager Mother Just Served Up Nuts."

      Thanks for the comment Silver Poet!

    • Greensleeves Hubs profile image

      Greensleeves Hubs 5 years ago from Essex, UK

      Interesting, and I think I agree with you. I had always thought that the reason Pluto had been disqualified as a planet was because of its possible place of origin out in the Kuiper Belt. That never seemed like an adequate reason for disqualifying Pluto to me, and neither does the reason which you say is the official explanation.

      What if Jupiter had another object of almost the same size as it, interacting in a similar way to Neptune and Pluto? Would the second object have to be regarded as a 'minor planet' even if it was bigger than Saturn?

      I agree it doesn't seem like a good reason for discarding Pluto from the list of planets.

      For me, the only two factors which should matter are that the primary orbit should be around the Sun, and the object should be massive enough to be effectively spheroidal.

      So yes, I think Pluto should be a planet too.

      Thanks for the hub. Interesting.

    • crashcromwell profile image

      crashcromwell 5 years ago from Florida

      Well Greensleeves, thanks for your insightful comment. It will be interesting to see actual images of the Plutonian system in a few years when the New Horizons probe does a fly by of Pluto in July of 2015. I recall hearing about that mission a while back that in order to traverse the billions of miles it must go to reach Pluto in 10 years, this probe is traveling faster than any other satellite humans have created. As a result, it would be impossible to slow down the probe enough to insert it into an orbit around Pluto, which means that NASA will have one chance only to learn all that it can about this tiny little planet.

    • Daisy Mariposa profile image

      Daisy Mariposa 5 years ago from Orange County (Southern California)

      I agree with the hub author, as does my boyfriend. My boyfriend once heard the discoverer of Pluto, American astronomer Clyde Tombaugh, give a lecture. My boyfriend has a master's degree in astronomy, and wonders if the International Astronomical Union (IAU) was eager to approve a new definition of planets which excluded Pluto from being a planet, because it was discovered by an American. He particularly regrets that American astronomer Neil Tyson, who appears on the PBS show NOVA, took an active role in the demotion of Pluto from planet status.

    • crashcromwell profile image

      crashcromwell 5 years ago from Florida


      As I read your note, I recalled seeing a show on the Discovery Science Channel in which Neil Tyson was the chief person defending the decision to reclassify Pluto, and I discounted the theory you advanced based on that. But then I saw you mention his role in it. In the broad scheme of things, it's probably not a big deal what the IAU did. It's not like Pluto suddenly ceases to exist because of this, and I am sure that the vast majority of people who have ever heard of Pluto still think of it as a planet. However, what I find as curious is that these yahoos have so much time on their hands that they need to waste time reclassifying Pluto. Isn't there something substantive they could be spending their time on? Thanks for the comment Daisy!

      Jim, aka Crash Cromwell

    • Daisy Mariposa profile image

      Daisy Mariposa 5 years ago from Orange County (Southern California)

      Crash: My boyfriend's comment on the added third planet criterion that disqualified Pluto: Pluto has large icy objects in "it's neighborhood", which it has not "cleared out". In the early era of the solar system, there were many planetismals in the inner solar system. The reason they've been cleared out of the Earth's "neighborhood" is almost all due to the gravitational effects of Jupiter. By the IAU reasoning, therefore, the Earth isn't a planet!

      As for Tyson, I think he has issues. I was once shocked to see him give a mini-rant on one of his Nova shows that he would have been an astronaut except he's black and NASA discriminated. Maybe they did, but there's a time and place for everything.

    • crashcromwell profile image

      crashcromwell 5 years ago from Florida

      Wow, never saw that rant. But considering Tyson's age, I would guess he would have been an astronaut candidate back in the Apollo era, and it is entirely plausible that there could have been discrimination going on in that day and age.

      As far as the early history of the solar system is concerned, I know what you are talking about. In fact, it is widely speculated that the moon was created when a Mars-sized planet that happened to share space in Earth's orbit struck the planet, and a big hunk of the Earth became Luna. My suspicion is that the IAU would justify this by saying that by this advanced date in the history of the solar system, if a celestrial object were going to clear the neighborhood, it would have done so already. Thanks for the comment!

      Jim, aka Crash

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      thierry henry 5 years ago

      i agree pluto should be a time give reasons why you think pluto should be a planet

    • crashcromwell profile image

      crashcromwell 5 years ago from Florida

      I think I did give reasons why Pluto should be a planet, so your comment confuses me a bit. Thanks for writing, though!

      Jim Henry, aka Crash Cromwell

    • Civil War Bob profile image

      Civil War Bob 5 years ago from Glenside, Pennsylvania

      Good hub, Crash...voted up, useful, interesting. Well, they may decide Pluto is not a planet, but he'll always be Mickey Mouse's dog!! Enjoy the day!

    • crashcromwell profile image

      crashcromwell 5 years ago from Florida

      Thanks Bob! The thing that bothers me about it is that for decades Pluto was a planet. An oddball, but still a planet. Then all these astronomers who apparently have nothing better to do with their time than to reclassify planets decide this needs to change. It reeked of internal politics in the scientific community. At the end of the day, Pluto is still out there, and I would bet that if there were any Plutonians, they would not care whether astronomers on a far-off planet like Earth thought their little hunk of rock was a planet or not. Thanks for the comment!

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      shoezimm 5 years ago

      The description of planets having to clear their paths does not take into consideration Lagrangian points... Earth, Mars, Jupiter and Neptune have so far been discovered to have bodies lingering in these "points" in their orbits, either before or behind them. Why are they not being demoted to dwarf planets when there are still items that are obviously not moons, but are still stuck in their line or orbit?

    • crashcromwell profile image

      crashcromwell 5 years ago from Florida

      That is a very good question, but sadly not one I could answer myself. It would be wonderful to find a member of the scientific community who supported this change in classification to explain why they do, and to respond to questions like this. Thanks for the note!

      Jim Henry, aka Crash

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      alice m 5 years ago

      yeah i agree.this is right compared to what i thought.

    • crashcromwell profile image

      crashcromwell 5 years ago from Florida

      What did you think before reading this hub? And thanks for the comment!

      Jim Henry, aka Crash

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      Bobughu 4 years ago

      In my opion it's a planet

    • profile image

      Robert 4 years ago

      It needs to have an orbit clear of objects bigger than it. And besides more than half of it's mass is ice and it gets a tail (like a comet) when it nears the sun.

    • crashcromwell profile image

      crashcromwell 4 years ago from Florida

      Sorry Robert, but that is kind of counter-intuitive. If there is something larger than the planet, and there is a collision, odds are the smaller object disappears. You cannot expect a smaller object to clear the orbit of items larger than it is.

      Now, what HAS Pluto done? Last time I checked, Pluto has captured several Kuiper Belt objects which have become its satellite system. So it sounds to me like Pluto is the biggest fish in this small pond.

      Meanwhile, your argument regarding the ice content of the planet falls flat with me for one simple reason: The surface of the Earth is 2/3 covered with water, a great proportion of which, I am sure, turned to ice in the Ice Ages, and I would bet that as Earth comes closer to the sun during those times it would develop a tail as well.

      So you have not persuaded me Robert, but thanks for the comment!

      Jim Henry, aka Crashcromwell

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      TIFFANI ARENAS 4 years ago


    • profile image

      Stuckinthe40s 4 years ago

      I found this article incredibly ignorant. You copied information from this article:

      But didn't bother to continue reading. "Clearing the neighborhood" does NOT mean how close to the sun it gets. Let me fill in the holes:

      "As planets form, they become the dominant gravitational body in their orbit in the Solar System. As they interact with other, smaller objects, they either consume them, or sling them away with their gravity. Pluto is only 0.07 times the mass of the other objects in its orbit. The Earth, in comparison, has 1.7 million times the mass of the other objects in its orbit.

      Any object that doesn’t meet this 3rd criteria is considered a dwarf planet. And so, Pluto is a dwarf planet. There are still many objects with similar size and mass to Pluto jostling around in its orbit. And until Pluto crashes into many of them and gains mass, it will remain a dwarf planet. Eris suffers from the same problem."

      Yes, it has a gravitational force, but that gravitational force is FAR too weak to drag much into it. Hence, dwarf planet. It's kind of a planet, but it is missing that last requirement to make it an official planet. Like the article said, let it crash into a number of smaller things to gain mass and increase gravitational force.

      Please, finish reading your sources before you throw around information.

    • profile image

      lily 3 years ago

      Oh yeah, stuckinthe40s guy

      where u get ur info? Have u thought maybe copy this article? Anyway, i have an interest in pluto. Demoting it from its title is a huge step backwards. Astronomy is progress and discovery. I think it is irrelevant. Important objects wont have an apportunity to be widely known as others. The problem is not Pluto, it is astronomers in the IAU. They are too ignorant to realize that they r making a huge mistake. Comments welcomed. Especially negative comments. P.S i am 12 yrs old. I am above average with an IQ of 144.

    • profile image

      lily 3 years ago

      Crashcromwell, please comment on my ideas. It would mean a lot to me. Thank you.

    • crashcromwell profile image

      crashcromwell 3 years ago from Florida

      Stuckinthe40s guy, I gave credit to universetoday, and I chose to extract from that source the criteria the astronomical community used to differentiate between a planet and a dwarf planet. The rest of the article I will readily admit is based on decades of fascination with all things space, since my fourth grade science fair project on the solar system.

      What I find outrageously funny is that with all the things there are to explore and discover in space that the demotion of Pluto from planet to dwarf planet was so important to the astronomical community. Whether one calls Pluto a dwarf planet or a planet really is immaterial. Of all my 106 hubs, this one is one of the most visited and active hubs of the lot. Obviously people still have an affinity for Pluto. I, for one, cannot wait until New Horizons arrives in Pluto starting about a year from now, because it will be the first time we get to see the Plutonian system up close.

      Lily, thanks for taking time to respond!

      Jim Henry, aka Crash

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