Between Asteroids and Planets: A New Category?

Our current classification schemes for celestial objects are becoming more and more inadequate as new discoveries are being made. An article published in the October 9, 2009 issue of Science presents compelling evidence that Pallas, located in the asteroid belt between Mars and Jupiter and considered an asteroid since its mid-19th-century demotion from planethood, is not an asteroid at all, but an object of an intermediate category between asteroid and planet, described by some as a "protoplanet," a "planetary embryo," and/or a "baby planet."

Protoplanets are usually thought of as the precursors to full planets during the early formation of solar systems. They are objects in the process of accreting in a protoplanetary disk around a protostar (a star that has not yet ignited through hydrogen fusion). Our early solar system was much more active and violent than today's, as objects in the protoplanetary disk regularly impacted one another and some began the runaway growth that would eventually transform them into full blown planets.

The asteroid belt between Mars and Jupiter is composed of objects that never accreted into a single large planet, mostly because Jupiter, with its strong gravitational field, gobbled up most of the material in that region for itself.

Researchers including Britney Schmidt, who did a very thorough presentation on Vesta and Pallas at the Great Planet Debate, used the Hubble Space Telescope to study Pallas in depth and found that unlike most asteroids, this body is not simply a loosely-held together rubble pile. Measuring 165 miles in diameter, Pallas has surface features and color variations that indicate it experienced thermal evolution and had the potential of growing into a full blown planet.  Pallas may even have some degree of geological differentiation. The researchers theorize Pallas formed from water-rich material and began to experience the same geological differentiation seen on planets, with heavy elements sinking to the core and lighter ones rising toward the surface.

In fact, Pallas, like Vesta, may once have been spherical. An impact crater examined by the researchers indicates Pallas was impacted by a large object some time in its past.

In the words of the "Discovery Space" web site, which can be found at http://dsc.discovery.com/space/big-pic/hubble-pallas-asteroid-protoplanet.html , "The Hubble Space telescope has taken a look at the large asteroid 2 Pallas and realized that this isn't just another large rock with a crater in it. Pallas is a protoplanet."
Opponents of using the criterion of hydrostatic equilibrium as an identifying feature for objects to be designated as planets often raise the question of "borderline" objects about which it is difficult or impossible to tell whether hydrostatic equilibrium has been attained. What is interesting here is that Pallas is almost but not quite spherical, just short of being in hydrostatic equilibrium. That makes it, like Vesta, one of those "borderline" objects skeptics often raise in their arguments.

While Pallas had the geology that put it on the path of becoming a planet, including liquid water and geological processes, the process was stopped and frozen in place early in the lifetime of the solar system due to Jupiter's gravitational influence. Yet Pallas, which researchers say "is closer to a planet than to a typical asteroid," remained largely intact in spite of early impacts, making it--and Vesta--unique solar system objects, essentially "fossils" representing a state all planets went through on their journey to becoming planets.

In his October 8, 2009 column, Alan Boyle states: "The bottom line is that Pallas is, well, right on the line when it comes to the important features dividing the solar system's big planets and dwarfs (and, for that matter, roundish natural satellites such as our moon) from irregular objects such as small asteroids and comets." See http://cosmiclog.msnbc.msn.com/archive/2009/10/08/2092402.aspx

What this means, is that any classification system for this and other solar systems, if purporting to be accurate, essentially requires a new, intermediate category between asteroid and dwarf planet (I'm using dwarf planet as a subclass of planet for objects that orbit stars and are in hydrostatic equilibrium but do not gravitationally dominate their orbits--Stern's "unter planets"). Assigning Vesta and Pallas to the asteroid category does not do them justice because it tells us nothing about their advancement beyond the state of most asteroids, erroneously placing them in the same grouping as large rubble piles that never came close to being shaped by their own gravity. We can call this intermediate category "protoplanets," "planetary embryos," "baby planets," or something else, but for the sake of accuracy and thoroughness, astronomers must designate a new and separate category for them.

We may discover some borderline Kuiper Belt Objects that also fall into this protoplanet category. This would provide an answer to the skeptics who ask about those objects on the "borderline."  Incidentally, Pluto, Eris, Haumea, and Makemake do not fit into this category, as their being in hydrostatic equilibrium is not in doubt.

Should protoplanets be considered a subclass of planets? Maybe the answer is to establish a spectrum that reflects what is really out there instead of neatly putting things into categories, resulting in unlike bodies thrown together in classifications such as the IAU's "small solar system bodies." We have such a spectrum for stars, the Herszprung-Russell Diagram, and it has been modified with the addition of extra categories to account for brown dwarfs, a class of objects on the bottom of the stellar category, massive enough to fuse deuterium (an isotope of hydrogen) for a short time but not massive enough to ignite as full-fledged stars. Protostars, "baby stars" in the process of formation, stars that have not yet "turned on" and begun hydrogen fusion, still have a place on the Herszprung-Russell Diagram. Why not set up a similar diagram for planets with "protoplanets" at the bottom, just above asteroids. This seems far better and more comprehensive than throwing a very diverse group of objects together under a broad wastebasket category called "small solar system bodies."

Creating such a system should not be the big deal it has turned out to be. And it does not have to be done by the IAU. Instead, how about planetary scientists getting together and working on a useful classification system? It's about time.

What Not to Teach or Display in A Classroom

Here is the poster child for what not to display in classrooms and what should not be taught to children: http://davidwboswell.wordpress.com/2009/09/20/pluto-correctness/ . Blogger David Boswell displays this image under an entry titled “Pluto Correctness,” illustrating an actual poster in his daughter’s preschool classroom.

If a picture is worth a thousand words, this is clearly the picture for the worst possible education children can be given about the solar system. Pluto crossed out—what is the message here? Circling and crossing out exercises are often used with preschoolers. The general idea is circle the right answer and cross out the wrong one. For example, a worksheet will show several objects and ask children to cross out the one that doesn’t belong. A typical assignment might show a truck, a motorcycle, a car, and a television. Crossing out the television, the correct choice, indicates that the television does not belong since the other three objects are vehicles, and the television is not.

In her fantasy novel A Wind in the Door, Madeleine L’Engle invokes the image of “Xing” or crossing things out as a way of negating their very existence. The antagonists in the story seek to “X” whoever they view as a threat to their frightening plans for the universe’s future. Those who are “Xed” are as though they never were.

That is why, as a L’Engle fan, I have never been comfortable with the labeling of my generation as “Generation X.” It sounds too much like a baby boomers’ decision that the generation succeeding them doesn’t exist, has no identity of its own.

So what are the lessons of a solar system display with Pluto crossed out? Some of the likely resulting beliefs by preschoolers who see this are that Pluto no longer exists, that it has been destroyed, that it was imaginary and never existed, that it is really an asteroid, that it was hit and destroyed by an asteroid or by aliens, etc. Every one of these reactions has been reported by parents, teachers, and siblings from young children’s discussions of Pluto.

Boswell erroneously states, “It’s been long enough that younger kids have grown up only knowing that Pluto used to be a planet. It’s a paradigm shift in action with the new generation simply accepting the new status as normal while any disagreements among older generations start to fade away.”

Wow, is he wrong, and on many levels. His views are very much in conjunction with the IAU’s repeated attempt to suppress any continuing debate on planet definition. The problem is, if one has to suppress debate to force an opinion on others, that usually means that opinion is not fully accepted and deep down, those suppressing opposition know that.

Thanks to conscientious teachers, parents, writers, and amateur astronomers, kids are not growing up with simple blind acceptance of a position that is still part of an ongoing debate. Instead, they are growing up learning that some issues can be looked at from multiple viewpoints, that some questions still do not have a single answer, even among the world’s top scientists. The disagreements among the so-called “older generation” are not “fading away.” They are as active as ever, and to say otherwise is a tremendous disservice to children.

In fact, the real paradigm shift is not going from nine to eight planets; it’s going from nine to numerous planets, and that is just in our solar system. This is the paradigm shift so many have trouble accepting, as can be seen from remarks like, “If we count Pluto, then we have to count hundreds of objects in our solar system as planets.” Well, yes, we very well may have to count hundreds of objects in the solar system as planets. Why is that a problem? Who originated the idea that kids cannot understand that our solar system contains four terrestrial planets, two gas giants, two ice giants, and numerous dwarf planets, all of which fall under the umbrella of planets? Whoever did is seriously underestimating the learning capacity of children.

Interestingly, a CNN poll conducted on August 24, 2009, the third anniversary of the IAU’s disastrous decision, resulted in 83 percent of respondents supporting Pluto’s formal reinstatement as a planet. Such a profound public endorsement shows that Dr. Stern is correct in his assessment that people know a planet when they see one. They see a spherical object orbiting the sun, and in spite of convoluted logic about what it means for an object to clear its orbit, they recognize that object as a planet. Don’t expect any “fading away” of Pluto’s planet status, or that of dwarf planets, any time soon.

At the same time, a science quiz by the Pew Research Center takes the wrong approach with a badly-worded question, “According to most astronomers, which of the following is no longer considered a planet,” then listing Neptune, Pluto, Saturn, and Mercury. According to most astronomers? Has Pew taken a poll? How do they come by this information when 96 percent of IAU members never took part in the vote, hundreds of professional astronomers opposed the decision, and many astronomers do not even belong to the IAU. Pew should do the right thing, and re-word this question with only one change. It should read, “According to some astronomers, which of the following is no longer considered a planet?” What they have now is a disservice and not a valid scientific knowledge survey.

Since one focus of this blog is to keep track of opposition to the IAU definition, it is appropriate here to congratulate McDonalds for distributing Happy Meal boxes reading “There are nine planets in total” in our solar system (http://deadlinescotland.wordpress.com/2009/10/04/10185-1916/ ). Some have gone so far as to accuse Ronald McDonald of “conning” kids into believing Pluto is still a planet. The real con, however, is by the IAU, which is attempting to force its one controversial view on the world as fact.

The IAU cannot even agree on what its role in astronomy is. Several IAU members have commented that their planet definition was never meant to be imposed on the entire world, that it is for internal use by IAU members only. Yet at the same time, the same people scream bloody hell when their definition isn’t followed. Scientist Paul Murdin calls McDonald’s inclusion of Pluto on these boxes as “a shame,” while the editor in Chief of the Encyclopedia of Astronomy and Astrophysics has stated, “McDonald’s have got this wrong. It’s a shame they didn’t check their facts.”

No, it’s the IAU that has it wrong. In fact, McDonald’s spokespeople have noted they are quite aware of the Pluto debate and rather than having gotten the facts “wrong,” they simply have chosen to join the many who reject the IAU’s controversial demotion of Pluto.

I would encourage McDonald’s to go further and add Ceres, Haumea, Makemake, and Eris to the Happy Meal boxes.

And while fast food is admittedly not the best choice healthwise, I encourage those who plan to purchase it anyway to vote with their dollars and support McDonald’s Happy Meal nine-planet boxes.

There are other ways to vote with one’s dollars as well. Jewelry designer Adriana Soto sells Planet Pluto Earrings and Planet Pluto Bracelets at this site: http://urbanheirlooms.blogspot.com/2009/09/planet-pluto-earring-284.html http://urbanheirlooms.blogspot.com/2009/09/290-planet-pluto-bracelet.html

Now, once more about that old, tired claim that it is only Americans who oppose the demotion of Pluto: the fact is, a very large number of the world’s planetary scientists are American, and planetary scientists make up the bulk of those who oppose the IAU planet definition. It is not surprising that the US is home to the largest number of planetary scientists, considering that the US led the space race and planetary missions for several decades. The issue is not whether Pluto is an “American” planet but the fact that those who study planets are heavily concentrated in the US, which has led the world in planetary research that has transformed the objects in our solar system from little more than names and tiny dots in a telescope’s field of view to real, up close, active worlds. Likewise, it makes the most sense that those who study planets would want a definition based on the traits of the objects they study rather than one based solely on where those objects are.

Finally, in terms of suppressing debate, that offense is being done solely by the pro-IAU camp. Opponents of the IAU definition have no problem admitting there is an ongoing debate, unlike supporters, who insist the debate is over. It seems the latter group is quite perturbed that what they thought was resolved their way has not been resolved at all!

Maybe that’s why Mike Brown has now formally banned me from his blog. That’s right. His reasoning is that I made “uncivil” comments there, but the reality is that went both ways. I did not insult Brown until he referred to me on Twitter as a “nutter,” prompting a British astronomer to write an entire blog entry called “Engaging the Loonies.” To that astronomer’s credit, he removed the offending entry when confronted about just how below the belt it was.

As for the statement that got me banned from Brown’s blog, it was a private email in which I vowed to undo his “killing” of Pluto and noted that even if he banned me, there are many other Pluto supporters active online, and he can’t ban them all.

Over at Alan Boyle’s “Cosmic Log” blog, one commenter, using the name “Harold Nations,” was right on about the suppression of debate by Brown and other supporters of Pluto’s demotion. With no prompting or input from me whatsoever, he wrote the following:

“A thing I find interesting in this debate is that Mike Brown clearly, originally, wanted Eris to be called the tenth planet and for obvious reasons.  He even posted the most telling thing I've ever read in the debate, that the word "planet" is clearly a cultural, not a scientific definition, much like the word "continent".  THEN, for reasons known only to himself, he decided to become oh so politically correct on the entire issue.  Had he stuck to his guns, there would NOT be a debate today, perhaps.  He's been debated time after time by Laurel Kornfeld on  his blog over planet nomenclature, and he's lost so many times he's now banned her from his blog.”

Source: http://cosmiclog.msnbc.msn.com/archive/2009/08/05/2020560.aspx

To get back to kids, these kids at the Music Tapes who made “For the Planet Pluto 3” make a definitive statement in their video by ultimately rejecting Pluto’s demotion and welcoming it back to planet status. “Out of the mouths of babes…” Visit http://opticalatlas.com/2009/08/video-the-music-tapes-for-the-planet-pluto-3/ to see this humorous, heartwarming video and song, as this debate continues.