At this time, when we are discovering more types of exoplanets than we could have imagined, we should be broadening, not narrowing the concept of planet. If that means we have 200 planets in our solar system, then so be it. Memorization is not as important as is understanding the characteristics of the different types of planets. So we could divide the broad term planet into subcategories such as terrestrial planets, gas giants, ice giants, dwarf planets, etc. Yet all would still be planets. This classification would acknowledge the significant differences between inert, shapeless asteroids, and objects like Ceres, Pluto, and Eris that have achieved hydrostatic equilibrium.

Telling people to “get over” a decision we believe is scientifically wrong and was established by a closed, backroom process is ridiculous and nothing more than a personal attack, which is what people make when they have no arguments to back up their viewpoints.

As for the 11-year-old in Catholic school being taught that we have only eight planets, she and her classmates are not getting the whole truth, which is a disservice to them. Children can understand that some debates remain open, that different experts can observe the same facts and reach different conclusions. Teaching only one view is teaching dogma, plain and simple. Schools should use this opportunity to help children learn that some issues are open-ended and have more than one answer and that the process by which decisions are made are as important as those decisions themselves.

(Though still not exactly “years ago” . . . )

At least I got the August part right . . .

“Pluto was kicked out years ago.”

More like six months . . .

[[How about: “my very enormous member can jam sperm under nancy’s puffy exit.”]]

I think Nancy may just slap you upside the head when you get home.

Yeah, Pluto could be defined as both, as well as Eris and Ceres. I just think that things as they are now work better when you consider Ceres to be an asteroid (based on size, composition and location relative to other asteroids), Eris and Pluto as KBOs (again, based on the same). Then Mercury, Venus, Earth and Mars as terrestrial planets (as they are rocky worlds in areas that are, relatively speaking, empty and located closer to the center what was once the proto-planetaru disk, where the heavier elements that make them up would be expected) and Jupiter, Saturn, Uranus and Neptune as the gas giants (with their own traits and characteristic that should be obvious).

So far, the biggest reason that I’m always hearing as to keeping Pluto a planet is always more of a dogmatic answer rather than one based on observations or data (i.e. “Pluto will always be a planet to me!”). Maybe I’m just not listening to the right people, or the right people’s voices are being drowned out be the swaft of uneducated people who just cry “Pluto will always be a planet to me!” (as a Christian who believes in a figurative genesis and that religion should be changed to support science discovers, I know how that feels). Maybe when the essays in Seattle are done, they’ll post some. I think that it’s marvelous that they are getting kids to look at this critically, even if it is in opposition to my personal preference. I’m just hoping that the essays, at least from the high schoolers, have some real thought behind them.

Some other things:
1) Concerning Jupiter clearing out it’s orbit arguement – This is specifically why I think that the definition is poor or should be dropped altogether and we just look at all this planet crap on a case by case basis. Yeah, there as asteroids in Jupiter’s orbit which have not been “cleared out”, but they are being herded by Jupiter’s gravity. It’s clear who in control in Jupiter’s neighborhood.
2) Yeah, if we want to pick nits, the definition only applies to the solar system. But come on! Like you can’t easily take this definition and use it when looking at other systems? Wow, that’s narrow minded.

I think that the kicker question is this: If Pluto were found today, knowing what we know now about KBOs, would it be a planet? I doubt it. The only reason why Eris is being questioned about planet or KBO is because its larger that Pluto.

826 SEATTLE AND GREENWOOD SPACE TRAVEL SUPPLY ANNOUNCE “PLUTONIAN” PROTEST AND RALLY

On Saturday, March 15th, 2008 from 4-5PM, 826 Seattle and Greenwood Space Travel Supply, located at 8414 Greenwood Avenue North, are protesting the 2006 International Astronomical Union’s reclassification of Pluto as a “dwarf planet.” This event is free and open to the public.

826 Seattle is the city’s only writing center entirely dedicated to helping students, ages 6 to18, improve their written communication skills. All 826 programs are structured around the belief that great leaps in learning can happen with one-on-one attention and that strong writing skills are fundamental to a young person’s future success. With the help of hundreds of volunteers, 826 Seattle offers free after-school tutoring, special writing workshops, class field trips, in-school programs, and publishing opportunities for Seattle students to improve their ability to communicate effectively in writing. 826 Seattle is supported in part by the Greenwood Space Travel Supply storefront.

The “Pluto IS a Planet” protest march and rally is the culmination of a two-day persuasive writing workshop geared towards youth ten years and older. The march begins at The Greenwood Space Travel Supply Co., travels north on the sidewalks of Greenwood Avenue to 87th Street, and returns south at Neptune Coffee, located at 8415 Greenwood Ave North. At the rally, before a panel of experts, workshop participants will read their persuasive arguments as to why Pluto should be reclassified as a planet. Experts include professional persuasive author, Seattle Times columnist Nicole Brodeur, professional persuasive speaker, lawyer Shawn Rediger, and local rocket scientist Tim Lloyd.

# # #

For more information, please contact Justin Allan, Store and Events Manager at (206) 725-2625 or go to http://www.826seattle.org.

As I’ve already said, I think the IAU’s decision to “demote” Pluto is warranted, as it really does appear to be a KBO, just as Ceres was reclassified as an asteroid in 1802.

@Elwood: ‘…and anyway if we keep changing our minds about things like this, it only gives ammo to the Anti-Science brigade who say “See? The scientists are always changing the facts! So it’s obviously all made up.”’

But that’s part of science! Updating and changing old ideas to represent a better understanding of the data is supposed to be central in scientific pursuit. When Pluto was discovered, it made since to call it a planet. But as time has gone on, we’ve discovered that Pluto isn’t this lonely little odd planet at the fringe of the solar system, but instead, part of another class of objects. Is it still worthy of recognition and the money it takes to study it? Heck yeah! But refusing to accept that Pluto really fits into the KBO classification better then the planet classification just because it clashes with existing world views? Isn’t that the kind of thinking that people like BA are fighting when they speak out against the Anti-Science brigade?

The mobile in my son’s bedroom says so.

You try telling him otherwise.

(Dadoo, I know exactly where you’re coming from.)

Gopher65′s definitions are much better.

And the Levinson equations tell how long a planet ought to take to clear their orbits. He solves for the current age of the solar system.

And isn’t “forcing into a resonant orbit” the same as “clearing”?

So did my very fat and very late aunt, but we didn’t call her a planet.

We called her “the human eclipse”, but never a planet.

My Very Educated Mother Just Said “Uh-oh! No Pluto!”

Hal Levison made an error in the first sentence of his paramaterizaion of the definition. According to the IAU, a planet is a celestial body that:

- is in orbit around the Sun,
- has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape, and
- has “cleared the neighbourhood” around its orbit.

Levison rephrased that third part of the definition as an “object large enough to clear its neighborhood of small bodies”.

The problem is that the IAU used the past tense (that the body has already cleared the neighbourhood), whereas Levison is stating a potential (that it possibly could).

According to the strictest interpretation of the IAU definition, there are only two planets in the universe: Saturn and Uranus. Extrasolar planets are not planets, because they don’t orbit the Sun. Mercury, Venus, Earth, and Mars have not yet cleared their neighborhoods of asteroids. Jupiter has trojan asteroids. Neptune has not cleared Pluto from its orbit.

My new mnemonic is therefore: Silly Universe!

We do need mnemonics any more. We needed them before we could visualized planets. Back then, planets were nothing more than a list of names. Now, planets are worlds. When I heard Neptune, I see Neptune in my head. Just show the children pictures about the planets as they learn them. Frankly, these meaningless mnemonics are harder to remember than just imagining the Solar System on a logarithmic scale with a picture of each planet enbiggened logarithmically. That is what I do.

Seriously, we’d better stop being lazy on Earth. I’m sure there’s kids orbiting some distant star who have to memorize 20+ planets with far more confusing properties.

Let’s cherish the star-crap we have, it’s all we’re gonna get out here.