Pluto Will Always Be Our 9th Planet
Posted by 5x5 on March 19, 2009 under Random Science | 
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Pluto 9 T-shirt
It was August 24th 2006 when 424 out of 10,000+ members of The International Astronomical Union (IAU) decided they would take their long week and bad moods out on Pluto and downgrade it to a “dwarf planet”. After all, all the other scientists headed home during the last day of the 10 day conference. How dare Pluto not clear the neighborhood around its orbit? Sorry Pluto, you no longer get to play in the sandbox with the big wigs.
The choice was clear. Declare several of the newly discovered Trans-Neptunian Objects, some larger than Pluto, planets or downgrade Pluto to a dwarf planet. The underwhelming and unconvincing vote details are available for your viewing pleasure on the IAU’s website.
While the vote does not speak of the term “Dwarf Planet”, definitions (.pdf) were established to define “planet”, “dwarf planet” and “small solar system bodies”.
IAU’s resoning can be read in their “Pluto and the Developing Landscape of Our Solar System“.
Honestly, I can see where they are coming from. As more celestial bodies are discovered, they need to be categorized. Please don’t tell me my grade school teacher lied to me though. Certainly, 100s of textbooks are not wrong. Pluto was discovered on February 18, 1930 by Clyde Tombaugh. Being a large, roundish shaped object in the sky that orbited the sun, Pluto was declared our 9th planet. That is how I will always define Pluto.
The State of Illinois agrees with me. On March 13, 2009, another group of self-important people took back Pluto’s planet status. I stand with The Ninety-sixth General Assembly of the Sate of Illinois on Senate Resolution SR0046 (.pdf)
If you want to do more to save the planet (Pluto that is) visit SavePluto.com. Even if Pluto does not fit the new definition of “Planet,” I believe it should be grandfathered in to prevent traumatization to generations raised on the fact that we have 9 planets.
Laurel Kornfeld said,
Only ONE Trans-Neptunian Object larger than Pluto has been discovered, and that is Eris. Pluto IS a planet because unlike most objects in the Kuiper Belt, it has attained hydrostatic equilibrium, meaning it has enough self-gravity to have pulled itself into a round shape. When an object is large enough for this to happen, it becomes differentiated with core, mantle, and crust, just like Earth and the larger planets, and develops the same geological processes as the larger planets, processes that inert asteroids and most KBOs do not have.
The IAU definition makes no linguistic sense, as it states that dwarf planets are not planets at all. That’s like saying a grizzly bear is not a bear. Second, it defines objects solely by where they are while ignoring what they are. If Earth were placed in Pluto’s orbit, by the IAU definition, it would not be a planet. That is because the further away an object is from its parent star, the more difficulty it will have in clearing its orbit.
Many believe we should keep the term planet broad to encompass any non-self-luminous spheroidal object orbiting a star.
We can distinguish different types of planets with subcategories such as terrestrial planets, gas giants, ice giants, dwarf planets, super Earths, hot Jupiters, etc.
We should be broadening, not narrowing our concept of planet as more objects are being discovered in this and other solar systems.
I attended the Great Planet Debate, which actually took place in August 2008, and there was a strong consensus there that a broader, more encompassing planet definition is needed. I encourage anyone interested to listen to and view the conference proceedings at http://gpd.jhuapl.edu/ You can also read more about this issue on my blog at http://laurele.livejournal.com
You can find the petition of astronomers who rejected the demotion of Pluto here: http://www.ipetitions.com/petition/planetprotest/
5x5 said,
This is fantastic information. Thank you!
Kelly Brown said,
Hi, gr8 post thanks for posting. Information is useful!
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