Sunday, August 9, 2015

An Open Letter to the 29th IAU General Assembly

August 9, 2015

Dear Dr. Montmerle, Members of the IAU Executive Committee, Members of the Secretariat, Members of the Commission on Public Outreach Information Management, Commission on New Media, Working Group on Planetary System Nomenclature, Working Group on Small Bodies Nomenclature, Working Group on the Public Naming of Planets and Planetary Satellites, Working Group on International General Assemblies, and Delegates to the 29th IAU General Assembly,

I am an amateur astronomer and freelance writer who is writing to respectfully request the General Assembly officially reopen discussion on the issue of planet definition for both our solar system and the countless others both discovered and waiting to be discovered.

Please note that I do not represent any government, space agency, space mission, company, or print or online publication in writing this. These views are solely my own and those shared by like-minded people who have signed petitions stating, “I agree that Pluto is a planet, and a better definition is needed.”

The last three years in general and the year 2015 in particular have been a time of momentous, historic discoveries in planetary science. The Dawn mission’s orbit of Ceres and the New Horizons flyby of Pluto have stunned the world, not just with beautiful pictures, but with compelling evidence that these are complex geological worlds undergoing active internal processes as we speak.

While much data awaits from both missions, the information we have to date shows that Ceres and Pluto are far more than spherical worlds. Ceres may have a thin atmosphere and possibly a subsurface ocean. It could be one of the solar system’s most active and prominent water worlds.

Pluto’s lack of craters, its unusual variety of terrains, stunning mountains, and flowing ices indicate it too is geologically active today and like Ceres, may harbor a subsurface ocean. Like its larger planet counterparts, it seems to have an internal heat source. Analysis of the orbital dynamics of the six-body system (Pluto, Charon, and four small moons) reveals that its four small moons do not solely orbit Pluto but orbit a barycenter between Pluto and Charon, making the Pluto system a true binary, with Pluto and Charon acting much the way stars in a double star system do.

Incredibly, New Horizons has shown us that Pluto in many ways is more like Earth than possibly any other solar system world. As NASA associate administrator John Grunsfeld noted, “With flowing ices, exotic surface chemistry, mountain ranges, and vast haze, Pluto is showing a diversity of planetary geology that is truly thrilling.”

The question of what constitutes a planet is about far more than Pluto. As astronomer Dr. David Grinspoon pointed out, the current IAU definition completely excludes exoplanets, of which we have now discovered close to 2,000.

It makes no sense to have one definition for planets in our solar system and another or none for the billions that orbit other stars or float freely in space. Doing this privileges Earth and its parent star in a manner that runs counter to the Copernican principle.

In 2006, the leadership of the IAU attributed the need to come up with a definition of the word “planet” to the discovery of Eris and other large Kuiper Belt Objects. New information frequently compels revisiting and revising our classification systems. The discoveries of 2015 and of the last three years once again compel a paradigm shift and revision in our understanding of planets and planetary systems.

In our own solar system, scientists have been stunned to find that what we thought were dead worlds are much more akin to their larger counterparts, in spite of their size.

In other solar systems, we have found a diversity of worlds in a huge variety of sizes and orbits, many in locations and situations previously believed impossible. These discoveries have often resulted in scientists noting a need to “go back to the drawing board” to develop a new understanding of planet and solar system formation.

At the 2012 GA, the IAU approved electronic voting for members not able to be physically present at the conference, a step forward I respect and applaud.

Now, it is time to take the next step, to act with the flexibility and open-mindedness that represents science at its best. No definition should ever be final because we constantly learn more, requiring us to revisit concepts we thought we thoroughly understood.

For these reasons, I ask specifically that you reconsider and place for a new vote Resolution 5b from 2006, which would establish “planets” as a broad, umbrella category under which both classical and dwarf planets would be included and that the definition of planet be expanded to include objects that orbit a star or are free-floating in space, to accommodate exoplanets and rogue planets.

Additionally, I ask that you remove all dwarf planets from the “Minor Planet” category, remove minor planet numbers given to them, and remove them from the auspices of the Minor Planet Center. The term “minor planet,” as noted by Dr. David Weintraub, refers to objects now classed by the IAU as “Small Solar System Bodies,” in other words, asteroids, comets, and centaurs, objects too small to be in hydrostatic equilibrium. The newly-revealed complexity of dwarf planets confirms they do not belong in this category.

I also ask that you consider classifying complex spherical moons of planets, which undergo the same processes as the terrestrial planets, as part of a new category of “satellite planets.”

Continuing to ignore these new developments will not make them go away and constitutes a disservice to science. I am sure you are all aware that at a debate last fall at the Harvard Smithsonian Center for Astrophysics, participants, including scientists, educators, and students, voted overwhelmingly in favor of Pluto being classified as a planet.

Other polls, including those of professional astronomers, have shown similar results; people with strong backgrounds in astronomy and planetary science have overwhelmingly shown their support for dwarf planets being classed as planets and for a definition that includes exoplanets.

If you do not feel ready to put a resolution on the floor of this year’s GA, at least set in motion a process of establishing a committee to revisit the issue for the GA in 2018. I urge you to reach out to members of the New Horizons team, the only people in the world who actually sent a probe to Pluto, as well as to a broad cross-section of planetary scientists, both amateur and professional, and even to the public for input.

Now is an ideal time for such an effort, as the Dawn and New Horizons missions have generated a revived interest in astronomy and space exploration worldwide.

Failure to adequately address this issue based on new data will eventually result in another organization or simply public usage taking it up and adopting a better planet definition. If the IAU seeks to remain in a leadership role in terms of safeguarding the science of astronomy, it is time to revisit this issue and allow the time and deliberation necessary for the development of a genuine consensus, reaching out to as broad a spectrum of people as possible through digital media.

Laurel E. Kornfeld, Highland Park, NJ, USA

1 comment:

StevoR said...

Great letter. I'd definitely second and would sign this too.