Pluto Is A Planet. So Why Was It Called Not a Planet?

Pluto is a planet: it’s round, it has many satellites, including a huge one (Charon), a complicated geography with mountain ranges and plains, and probable plate tectonic (thus Pluto is alive, geologically alive). Moreover, Pluto has a blue atmosphere, and plenty of water ice. It’s a world… and a wanderer (planet in Greek).

The announcement of Eris in 2005, an object 27% more massive than Pluto, created the impetus for an official definition of a planet. Considering Pluto a planet would have demanded that Eris be considered a planet as well. However, both Ganymede and Titan are larger than Mercury, and the former two are supposed to be “Moons”, not planets… 

A big deal was made that Pluto’s orbit intersects, or is somewhat entangled, with Neptune’s orbit: it has not “cleared its orbit”. The International Astronomical Union decided that when there is no clearance, there is no planet. That a world’s orbit intersects another should be irrelevant… because we know exoplanets have often migrated. Moreover Pluto’s orbit is transverse, with little intersection.

So what’s a planet? A body that has never undergone nuclear fusion and has enough gravitation to be round due to hydrostatic equilibrium, with or without plate tectonic, regardless of its orbital parameters. That would exclude white dwarves. Haumea, a large Kuiper mostly rocky object is not round at all.

Such a definition of a planet incorporates many of the so-called “dwarf planets”, including Eris and Ceres (the largest asteroid; it has water). But it would semantically turn Earth’s Moon into a planet. Is it? Well, there is a possibility that one could set an atmosphere on the Moon. It would seem all we need would be a powerful source of energy to get oxygen and water out of the Moon’s surface rocks: they seem to have plenty of both. 

In the popular imagination, a “planet” is a large, round, potentially habitable world… Like the mythological Pandora rotating around a giant planet from the Proxima Centauri system in the movie Avatar. We already know that this Red-Yellow Dwarf star has a radius one sixth that of the Sun. It is capable of flares of 27 million degrees Kelvin, emitting plenty of hard radiation, as large as the star, and increasing its energy output by a factor of eight. Most of its energy is in the infrared, and it has at least one planet with a mass similar to Earth inside its habitable zone… Although “habitable zone” around a flare star has to be taken with a grain of salt… As I pointed out many planets may turn out to be habitable for transhumans with very high tech, but be otherwise unhospitable for indigenous animal life

So why were some astronomers so insistent about Pluto not being a planet? Because then they could print t-shirts with “I have killed Pluto” emblazoned on it. People, especially children and those thoroughly immature, look for glory… thus showing that they feel they are not much, left to their own instruments… Demoting Pluto and making a big deal about it, claiming Pluto has been “killed”, is a perfect example of that.

Instead the important notion in planetary astronomy discovered in the last 20 years is probably that it seems there is much more water in the Solar System than anticipated… And this is very good news for space COLONIZATION (lack of water had been anticipated throughout the Solar System). Whether Pluto is a “Dwarf” or not, is a distraction for kindergarten… And we mention it here to show the folly affecting even scientists, trying to make themselves interesting, even with frivolous subjects.

Oh yes, and I mentioned “colonization”… I run with wild words I mount powerfully in my conquest of even wilder worlds. Colonization is assuredly not a politically correct word. Yet, colonization is Humanity’s main drive forcing its evolution… We all descend from colonizers. Considering the importance and nature of the concept of colonization in defining humanity, colonization has become assuredly the main reason to look out there… Now that colonization of the solar system becomes indeed possible.

Patrice Ayme

Here are 25 solar system planets and dwarves smaller than Earth… But there are others, roughly Pluto sized, like Eris, Makemake, and Haumea….

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5 Responses to “Pluto Is A Planet. So Why Was It Called Not a Planet?”

  1. domobran7 Says:

    Stupidity of redefinition of Pluto can be seen from a simple fact that Earth would be a moon if it orbited Jupiter instead of a sun… though I wonder how many planets Solar system does have if we include all objects that had formed into spheres and orbit the Sun. “Lonely in the orbit” doesn’t help as even Earth isn’t alone in its own orbit (there are IIRC two asteroid groups orbiting the Sun together with us).


  2. Ian Miller Says:

    Ian Miller
    If you accept the mechanism of planetary formation in my ebook “Planetary Formation and Biogenesis”, each planetary system (core of planet and satellites) has a different composition that led to their formation. In this part of the system, it is the sequential volatalization of ices that causes the difference. If so, the Kuiper Belt, and Pluto, are the tail remnants of Neptune’s formation, the tail being longer because out there the temperature gradient was smaller. So from that point of view, Pluto is not a different system, but really left-overs from Neptune’s formation.


    • Patrice Ayme Says:

      I thought the Asteroid belt was caused by Jupiter’s disruption of attempted planet there… Pluto has a transverse orbit… Anyway my point was rather semantics, hinging on planet migration as observed apparently out there


      • Ian Miller Says:

        Jupiter did partially disrupt the asteroid belt – there are the Kirkwood gaps where there are gravitational resonances, and they are a little asymmetric, indicating that at one stage Jupiter moved a very little bit inwards. This is probably due to a mean motion resonance with Saturn, which probably moved out somewhat more.


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