Tuesday, April 15, 2008

The Great Planet Debate--A Stellar Idea Whose Time Has Come

It’s happening at last! The conference aimed at addressing the planet definition issue, announced by Dr. Alan Stern immediately following the IAU’s controversial demotion of Pluto nearly 20 months ago, has been scheduled for August 14-16, 2008, at the Johns Hopkins University Applied Physics Laboratory in Laurel, MD (on a personal note, I can’t help but be amused at the name of the city chosen for the conference).

Co-sponsored by NASA, the Johns Hopkins University Applied Physics Laboratory, the Planetary Science Institute, the Planetary Society, and the American Astronautical Society, it is open to all interested members of the public and especially geared towards educators.

The conference title is “The Great Planet Debate: Science As Progress.”

While the initial idea of the conference was Stern’s, it is Dr. Mark Sykes, another leading proponent of Pluto’s planetary status, who is serving as event chair.

Days one and two will feature a discussion of both the IAU planet definition, based on dynamics, and an alternative geophysical definition. This portion will include a lecture and panel discussion and will be followed by a reception.

On the third day, an Educator Workshop will address the issue of dealing with the planet debate in schools and how to use it as a springboard to discuss science as a process.

The conference will feature a public debate--Neil deGrasse Tyson vs. Mark Sykes.

Information about the conference, including a registration form, schedule, and conference information, can be found at http://gpd.jhuapl.edu/

In an April 10 article, Scientific American makes note of the conference in an article titled “Is Rekindling the Pluto Planet Debate a Good Idea?”

A subtitle to the article quotes conference critics labeling the event “beating a dead planet.”

Naturally, proponents of the IAU decision want this to stay a closed subject. After all, if the debate is re-opened, the very shaky planet definition adopted by four percent of the IAU has very little real science on which to stand. When people think they have won a debate, the last thing they want to see is that debate re-opened.

But one cannot re-open something that has never truly been closed. And most certainly, the debate over Pluto’s planetary status has remained very much open over the last year and a half, beginning with Stern’s petition of 300 plus professional astronomers who signed within days of the demotion saying they will not use the IAU’s definition.

The objections by those who support the IAU decision, described in the article as “irking” some researchers, are worth examining exactly because, unintentionally of course, they reinforce the major problems with the decision.

Dr. Harold Levison, a planetary scientist at the Southwest Research Institute in Boulder, Colorado who agrees with the IAU decision, claims that fighting the decision does more harm than good to researchers’ reputations while in the same paragraph admitting he would have rather seen a more encompassing planet definition that divides planets into two subcategories, major and minor.

This appears to indicate he supports a definition with which he himself is not entirely comfortable. Why support something he recognizes as flawed instead of pushing for his superior definition? Sticking with a problematic definition is more likely to hurt researchers’ reputations than is keeping the issue open and standing up for an outcome he knows is better.

Levison also claims that Pluto’s orbital eccentricity somehow makes it stand out as less than a planet. Just how does that work? Mercury’s orbit is also somewhat eccentric, and Eris’ orbit is so eccentric it makes Pluto’s look ordinary. Why should having an eccentric orbit disqualify an object from being a planet? Many of the exo-planets we have discovered have very eccentric orbits. Does that make them not planets? More likely, the eccentric orbit of round objects in the Kuiper Belt simply makes them a new subcategory of planets, the ice dwarfs, still planets but with their own unique characteristics.

If there are dozens more objects in the Kuiper Belt that have achieved hydrostatic equilibrium and fit this decision, then there are dozens more of this subcategory of planets. It’s that simple.

Researcher and author Jack Lissauer, co-author of the textbook Planetary Sciences, is quoted in the article as recognizing the problematic nature of the IAU “dwarf planet” classification, claiming that if a Mercury-sized object were discovered in the Kuiper Belt, it likely would be considered a planet even though it doesn’t clear its orbital zone.

Now wait just a minute here. According to the IAU definition, even a Jupiter-sized object would not be a planet if it does not clear its orbit. So how and why could this Mercury-sized object qualify? That would imply that size rather than clearing its orbit is the criteria for planethood. Who decides, and based on what criteria?

It is through scenarios like this one that we can see just how flawed and untenable the IAU definition is.

Even more laughable are the “polls” cited by Professor Ed Prather of the Steward Observatory at the University of Arizona in Tucson, who teaches Astronomy 101 to non-science majors.

A supporter of the demotion, Prather says he regularly polls his students about the issue, and 70 percent respond saying there is no reason to classify Pluto as a planet, that it is simply a rock sitting “way out there.”

Have Prather’s students had the opportunity to hear both sides of the debate, or more likely, is the majority of this group of people who likely had no prior exposure to astronomy simply parroting the biased view their professor has pounded into their heads all semester long? One has to wonder.

It turns out Prather doesn’t like the idea of educators or members of the public taking part in decision making on scientific issues. Once the public perceives scientists making decisions based on “personal feelings and historical convention…we’ve dropped the ball.”

Sorry, professor, but an international organization of scientists that cannot enact electronic voting and rushes through controversial decisions without sufficient debate with only four percent of its membership having a say has already “dropped the ball.”

As for the textbook publishers cited, they would do well to present the issue as an ongoing debate rather than rush to print new editions excluding Pluto from the cannon of planets. The issue is unresolved. Changing textbooks now is like the line from Kenny Rogers’ song “The Gambler” about counting the money when you’re still sitting at the table. If textbook companies insist on doing this, they likely will be caught up in an endless cycle of printings and re-printings each time a new decision is reached. Besides, what is wrong with portraying an issue as not having one clear answer?

Sykes is correct in his characterization of the IAU decision as “providing no insight” into the nature of celestial objects because it does not take into consideration the composition of those objects.

Like Stern and many other planetary scientists, he believes that an object that has achieved hydrostatic equilibrium, meaning it has sufficient gravity to have pulled itself into a round shape, should be considered a planet.

These objects all have geological processes such as volcanism, erosion, and plate tectonics, all of which clearly distinguish them from the asteroids with which the IAU assigns them the same category.

In summary, the Pluto planet debate is alive and well and will likely remain so for quite some time. Nothing can sufficiently prepare us for the voluminous amount of information we will obtain on the Pluto system when New Horizons photographs it in 2015, information that is sure to one way or another change our view of this enigmatic planet. At least until then, the debate must remain open.

For anyone interested, my March 9 radio interview on WNTI, 91.9 FM at New Jersey’s Centenary College, can be heard at http://www.publicbroadcasting.net/wnti/arts.artsmain?action=viewArticle&sid=9&id=1239341&pid=247
The recording is through the "Contours" program and occurs in the middle of the broadcast, about 17 and a half minutes in.

You can also find a hard copy petition to the IAU to download at http://groups.yahoo.com/group/friends-of-laurel/Files
Scroll down the list to “Pluto Petition.” An amateur astronomer friend of mine will be compiling these and sending them to the IAU in time for their 2009 General Assembly, so if you want to or have collected signatures, email me at laurelkornfeld@netzero.net and I will give you the address to which you can “snail mail” them. Hard copy petitions usually carry more weight than Internet petitions, so I encourage all Pluto supporters to take part in this.

I also want to personally encourage anyone interested in this issue to seriously consider attending the Great Planet Pluto Debate in August. Discussions and ideas presented during the conference could potentially be brought to light at the next IAU General Assembly in 2009. For this reason, those of us who support Pluto’s planet status should make every effort to attend and make our voices heard.

Sign up for the conference at http://gpd.jhuapl.edu/
I’m looking forward to seeing many fellow Pluto supporters there.

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