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Thursday, February 23, 2017

Pluto is still a planet, and geophysical planet definition proposal is not a "non-starter"

In his Feb. 22 New Scientist comment, "Pluto is Still an Ex-Planet," Mike Brown attempts to impose one view in an ongoing debate as fact.

The community of planetary scientists who support Pluto's planet status is not, as he describes, "a small but vocal group" and is not limited to those on the New Horizons mission. Neither did a "majority of astronomers" reject the notion of Pluto retaining its planet status in 2006.

With these statements, Brown presumes a consensus in the science community that never existed. Planetary scientists and astronomers were just as divided about Pluto's status and about how to define the term "planet" 10 years ago as they are today.

Only four percent of the IAU voted on the controversial 2006 definition, and most were not planetary scientists but other types of astronomers. Their decision was immediately rejected by an equal number of professional planetary scientists in a formal petition released just days later.

Brown's claim that nothing about Pluto has changed since 2006 ignores the extensive findings of the New Horizons mission, all of which show Pluto to be a geologically living object with wind-blown dunes like those on Earth and Europa; flowing glaciers not seen anywhere else in the solar system besides Earth and Mars; tectonic forces; an internal heat source; cryovolcanoes, and even a possible subsurface ocean. All these are features characteristic of planets.

His citation of the discovery of Ceres as a precedent actually works against the argument he makes. Nineteenth-century telescopes were not powerful enough to resolve Ceres into a disk, so astronomers of the day had no way of knowing that unlike the asteroids discovered after it, Ceres is in hydrostatic equilibrium. As shown by NASA's Dawn mission, Ceres is very different from the majority of asteroids, which are largely rubble piles. Like Pluto, it experiences complex geological processes and may harbor an underground ocean.

It is misleading to conflate the new proposal's inclusion of Earth's Moon as a satellite planet with the geocentric view of the universe held 500 years ago. Compositionally, spherical moons are much like the terrestrial planets except for the fact that they orbit other planets instead of orbiting the Sun directly. Designating them as "moon planets," as the proposal does, sufficiently distinguishes them from planets in primary orbits around the Sun.

We can have a scientifically consistent definition of planet that includes numerous subcategories to account for both orbital dynamics and intrinsic properties.

Saturday, February 18, 2017

87 Years of Pluto: Complete List of Signatories Who Signed 2006 Petition Rejecting IAU Definition

February 18, 1930, is a tribute to underdogs.

On this day, 87 years ago, 24-year-old Clyde Tombaugh, working at the Lowell Observatory with just a high school diploma, discovered planet Pluto using a blink comparator to move back and forth between two photographic plates of the same portion of the night sky, taken on January 23 and January 29 of that year.

Unfortunately, too often biased in favor of the controversial IAU decision, the mainstream media report that “Pluto was a planet for 76 years.” For many, ranging from top planetary scientists and astronomers to amateur astronomers to citizen scientists and members of the public, Pluto has been a planet—a known planet—for 87 years and counting.

Actually, Pluto has been a planet for four billion years and counting. It just took a long time for a late-coming species to the planet Earth to discover it.

Even ten-and-half years later, many people are unaware of basic facts about Pluto’s status—such as the fact that only four percent of the IAU voted on the definition that demoted Pluto, and most were not planetary scientists but other types of astronomers. In other words, they were NOT experts in this field and do NOT even study planets.

Just 333 of 424 IAU members present voted that dwarf planets should not be counted as planets, a misuse of the term “dwarf planet” as coined by Alan Stern, who intended the term to designate a third class of planets in addition to terrestrials and jovians.

Within several days, an equal number of professional astronomers and planetary scientists, about 300, signed a formal petition rejecting the IAU definition, a move that unfortunately got very little media attention.

For several years their petition and the names and affiliations of all signatories were posted online at . I am now reposting the wording of the petition as well as the names and affiliations of the signatories to keep this information available to the public.

“We, as planetary scientists and astronomers, do not agree with the IAU's
definition of a planet, nor will we use it. A better definition is needed.”

As noted on the original petition site, “In less than five days, the petition was signed by 300 professional planetary scientists and astronomers. The list of signatories includes researchers who have studied every kind of planet in the solar system, as well as asteroids, comets, the Kuiper Belt, and planet interactions with space environment. They have been involved in the robotic exploration of the solar system from some of the earliest missions to Cassini/Huygens, the missions to Mars, ongoing missions to the innermost and outermost reaches of our solar system, and are leading missions preparing to be launched. The list includes prominent experts in
the field of planet formation and evolution, planetary atmospheres, planetary surfaces and interiors, and includes international prize winning researchers.

“This petition gives substantial weight to argument that the IAU definition of planet does not meet fundamental scientific standards and should be set aside,” states petition organizer Dr. Mark Sykes, director of the Planetary Science Institute in Tucson, Arizona. “A more open process, involving a broader cross section of the community engaged in planetary studies of our own solar system and others should be undertaken.”

“I believe more planetary experts signed the petition than were involved in the vote on the IAU’s petition. From the number of signatories that the petition received in a few days, it’s clear that there is significant unhappiness among scientists with the IAU’s planet definition, and that it will not be universally adopted by scientists and text book writers. To achieve a good planet definition that achieves scientific consensus will require more work.” added co-sponsor Dr. Alan Stern, Executive Director of the Space Science and Engineering Division of the Southwest Research Institute.

The Signatories:



Hal Weaver                                        Johns Hopkins University Applied Physics Laboratory
Ralph McNutt                                   Johns Hopkins University Applied Physics Laboratory
Andrew Cheng                                  JHU/APL
Amy Lovell                                        Agnes Scott College
Darren Baird                                     UCLA
Christopher Russell                          UCLA
Elizabeth Jensen                                UCLA
Mark Sykes                                        PSI (Planetary Science Institute)
Michael Gaffey                                  Space Studies, U. North Dakota
John Lambert                                    The Boeing Company
Tony Farnham                                   University of Maryland
David Rabinowitz                              Yale University *(co-discoverer of Eris)*
Curtis Cooper                                    Lunar and Planetary Laboratory, University of Arizona
Alan Chamberlin                              Jet Propulsion Laboratory
H. Warren Moos                               Johns Hopkins University
Chris McKay                                     NASA Ames
Eldar Noe                                           Malin Space Science Systems
Scott Michael                                     Indiana University
Jennifer Piatek                                  University of Tennessee
Krista Soderlund                               UCLA
Sanjay Limaye                                   University of Wisconsin
Kathy Rages                                      SETI Institute
Erin Ryan                                          University of Minnesota
Beatrice Mueller                                Planetary Science Institute
Barry Lutz                                         Northern Arizona University
Stephen Maran                                  American Astronomical Society
David Kuehn                                      Pittsburg State University
Leslie Bleamaster                              Planetary Science Institute
Peter Bender                                      Univ. of Colorado
Kenneth Mighell                                National Optical Astronomy Observatory
Larry Lebofsky                                 U. of Arizona
Kem Cook                                          Lawrence Livermore National Laboratory
David Levy                                        Jarnac Observatory
Horton Newsom                                Univ. of New Mexico
Kurt Retherford                               Southwest Research Institute
Wendee Wallach-Levy                      Jarnac Observatory
Nanette Vigil                                      Jarnac Observatory
Francis Graham                                Kent State University
janet luhmann                                   SSL, Univ. of California, Berkeley
Bryan Butler                                      National Radio Astronomy Observatory
Harold Geller                                     George Mason University
Will Grundy                                      Lowell Observatory
James Dire                                         Gardner-Webb University
Nicola Richmond                               Planetary Science Institute
Peter Thomas                                    Cornell University
Howard Smith                                   University of Virginia
Alan Stern                                          SwRI (Southwest Research Institute)
Vladimir Krasnopolsky                    CUA (Catholic University of America)
Colleen Milbury                                UCLA
Britney Schmidt                                UCLA
Jennifer Benson                                University Of Toledo
Alan Howard                                     University of Virginia
Tae-Soo Pyo                                       Subaru Telescope
Wayne Pryor                                      Central Arizona College
Tanya Tavenner                                New Mexico State University
Steve Howell                                      NOAO
Robert Carlson                                  JPL
Jason Soderblom                               Cornell University
MARK WYSOCKI                          CORNELL UNIVERSITY
William Rossow                                City College of New York
William McKinnon                           Washington University
Jody Wilson                                       Boston University
Iain Reid                                            STScI (Space Telescope Science Institute)
Nadine Barlow                                  Northern Arizona University
Mark B. Vincent                               MRO 2.4m, New Mexico Tech
Philip James                                       Space Science Institute
Vishnu Reddy                                    University of North Dakota
Denise Stephens                                 Johns Hopkins University
Lawrence Wasserman                      Lowell Observatory
Colby Jurgenson                               Magdalena Ridge Observatory
Roger Knacke                                    Penn State Erie
Darrell Strobel                                   Johns Hopkins University
Steven Ostro                                      JPL
Ronald Elsner                                    NASA Marshall Space Flight Center
Robert Marcialis                               LPL (Lunar & Planetary Laboratory, Univ. of Arizona)
Mark Showalter                                SETI Institute
Linda Spilker                                     JPL
Larry Paxton                                     Johns Hopkins University
William Jackson                                University of California
Theodor Kostiuk                               NASA Goddard Space Flight Center
Robert Kolvoord                               James Madison University
Glenn Orton                                      JPL
Paul Strycker                                     New Mexico State University
Nicholas Sperling                              The University of Toledo
Mark Everett                                     Planetary Science Institute
D. Chris Benner                                College of William and Mary
Jim Elliot                                            Massachusetts Institute of Technology
Walter Huebner                                Southwest research Inst.
Michael Mickelson                            DENISON UNIVERSITY
Giles Marion                                      Desert Research Institute
James Ferris                                      Rensselaer Polytechnic Institute Institute
Henry Throop                                   Southwest Research Institute, Boulder, CO
Larry Petro                                        Space Telescope Science Institute
Chris Churchill                                 New Mexico State University
Gordon Bjoraker                              NASA/GSFC
Robert Fritzius                                  Shade Tree Physics
Daniel MacDonald                            JPL
Brendan Fisher                                 JPL
Linda French                                     Illinois Wesleyan University
Bernard Bates                                   University of Puget Sound
Richard Tresch Fienberg                 Sky & Telescope
Mary Bourke                                     Planetary Science Institute
Carol Neese                                        Planetary Science Institute
Ed Smith                                            STScI
Christopher Gelino                           Spitzer Science Center/IPAC
Richard Wagener                              Brookhaven National Laboratory
Truman Kohman                              Carnegie-Mellon University
John Stansberry                                Steward Obs., U. Arizona
Alex Storrs                                         Towson Univ.
G. Leonard Tyler                              Stanford University
Brandon Lawton                               New Mexico State University
Mark Hammergren                           Adler Planetarium & Astronomy Museum
Peregrine McGehee                          Los Alamos National Laboratory
Robert Seaman                                  National Optical Astronomy Observatory
Marc Buie                                          Lowell Observatory
Landon Noll                                       Fremont Peak Observatory
Adam Burgasser                               MIT
Michael Kelley                                  Georgia Southern University
Uwe Fink                                           Lunar and Planetary Laboratory, University of Arizona
David Crisp                                       JPL/Caltech
H. Bradford Barber                          University of Arizona
Einstein Miller                                   OCC, CU, MMCC
Robin Evans                                      Gibbel Corporation
Kurt Anderson                                  Apache Point Observatory and NM State University
Erik Asphaug                                    University of California, Santa Cruz
William Newman                              UCLA
Jose Francisco Salgado                    Adler Planetarium
Stamatios Krimigis                           JHU/APL
Michael Mautner                              Virginia Commonwealth University
Simon Mitton                                    University of Cambridge
Raul Baragiola                                  University of Virginia
Michael Allison                                  Goddard Inst for Space Studies
Cathy Olkin                                       SwRI
Judith Young                                     University of Massachusetts
Michael Kelley                                   University of Minnesota
Meg Spohn                                         University of Denver
Tashonia Blackwell                           Norfolk State University
Brian Warner                                    Palmer Divide Observatory
Alison Bridger                                   San Jose State University
Alanna Garay                                    National Astronomical Observatory of Japan
Henry Alwyn Wootten                      Natl. Radio Astronomy Observatory
M. L. Delitsky                                    CSE (College of St. Elizabeth)
Ira Nolt                                               Retired NASA
Jayant Murthy                                  IIA (Indian Institute of Astrophysics)
William Merline                                SwRI
Daryl Swade                                      STScI
Amar Rao                                          UCLA
Robert Novak                                    Iona College
Joe Peterson                                       Southwest Research Institute
Donald Jennings                                Goddard Space Flight Center
Michael Wolff                                    Space Science Institute
Randy Gladstone                              SwRI
Jeffrey Moore                                    NASA Ames Research Center
Fred Franklin                                    Harvard-Smithsonian CFA
Kevin Stube                                       University of Arizona
David Tholen                                     University of Hawaii
Russ Walker                                      MIRA (Monterey Institute for Research in Astronomy)
Eliot Young                                        Southwest Research Institute
Michael Finch                                    The University of Arizona
David Crown                                     Planetary Science Institute
William Cassidy                                 University of Pittsburgh
Joel Parker                                        Southwest Research Institute
Noel Jackson                                      University of Southern Queensland, Australia
David Portree                                    Lowell Observatory
Jonathan Gradie                               BAE Systems NES Imaging & Surveillance
Philip Massey                                     Lowell Observatory
Paul Grogger                                     University of Colorado
Joseph Ajello                                     JPL
Lou Weeks                                         AAS Member
Galen Gisler                                       University of Oslo
Thomas Stephens                              NASA GSFC
Jared Leisner                                     UCLA
Gregory Hoppa                                 Raytheon
Robert Barron                                   Tel Aviv Uni.
Laurent Montesi                                Woods Hole Oceanographic Institution
Deidre Hunter                                   Lowell Observatory
James Mueller                                   JHU/APL
Michael Stevens                                 Naval Research Laboratory
Scott Milster                                      ATK Mission Research
Hoi Fung Chau                                  University of Hong Kong
Knut Olsen                                         National Optical Astronomy Observatory
Anthony Roman                                Space Telescope Science Institute
Catherine Johnson                            UCSD
Grace Wolf-Chase                            University of Chicago
Bernard Noeller                                Community College of Baltimore County
Ellen Howell                                      Arecibo Observatory
Robert Reynolds                               University Of Arizona - LPL
Thomas Kehoe                                  University of Florida
David Hinson                                     Stanford University
Dan Moynihan                                  Lunar and Planetary Laboratory
Glenn Dantzler                                  Settlemyre Planetarium
Thomas Hill                                       Rice University
Justin Bartel                                      Kansas Cosmosphere and Space Center
Rodney Martin                                  Wm. Brish Planetarium
Steven Russo                                      Schenectady Museum Planetarium
Maurice Collins                                 Amateur Astronomer
Douglas ReVelle                                Los Alamos National Laboratory
John Cooper                                      NASA Goddard Space Flight Center
Martha Leake                                   Valdosta State University
JOHN BRANDT                               U. of New Mexico
Duncan Young                                  University of Texas
Chuck See                                          University of Arizona
Stephen Becker                                 Los Alamos National Lab
Bonnie Buratti                                  Jet Propulsion Laboratory
Sally Oey                                           University of Michigan
Laurence Trafton                             Univ. Texas at Austin
David Bartlett                                    University of Colorado
Faith Vilas                                          MMT Observatory
David Grinspoon                               Denver Museum of Nature & Science
Carolyn Shoemaker                          USGS
Robert Craddock                              Smithsonian Institution
Priscilla Cerroni                                IASF INAF Roma Italy
John Dragon                                      Los Alamos National Laboratory
Charles Cowley                                 Astron. Dept. U. of Michigan
Wayne Hayes                                     University of California, Irvine
Nilton Renno                                     University of Michigan
Amy Simon-Miller                             NASA Goddard Space Flight Center
Louise Prockter                                 JHU/APL
David Klassen                                    Rowan Univeristy
Bradley Schaefer                               Louisiana State University
Ilana Dashevsky                                STScI
Lawrrence Sromovsky                     University of Wisconsin - Madison
Richard Schmude, Jr.                       Gordon College
David Weintraub                              Vanderbilt University
Barbara Carlson                               NASA/GISS
Gary Copeland                                  Old Dominion Univsersity
Gerhard Neukum                             Freie Universitaet Berlin, Germany
Yi-Jehng Kuan                                  National Taiwan Normal University
Tom Van Flandern                           Meta Research
Edward Tedesco                               University of New Hampshire
John Richardson                               M.I.T.
Jon Jenkins                                        SETI Institute
Dariusz Lis                                         California Institute of Technology
Minho Choi                                        Korea Astronomy and Space Science Institute
David Dunham                                  Johns Hopkins Univ./Applied Physics Lab.
Michael Haken                                  NASA/GSFC
Craig Fry                                           Exploration Physics International, Inc.
Jean Chiar                                         SETI Institute/NASA Ames
Clark Chapman                                Southwest Research Inst.
Jasmine Santana                               University of Michigan, Ann Arbor
Laura Woodney                                California State Univ, San Bernardino
Fran Bagenal                                     University of Colorado
Gregory Smith                                   SRI International
Victoria Meadows                             IPAC/Caltech
Shane Byrne                                      University of Arizona
Steven Lee                                          Denver Museum of Nature & Science
Susan Postawko                                University of Oklahoma
Michael Summers                             George Mason University
Amy Donnelly                                    Herkimer BOCES Planetarium
Joseph VEVERKA                           Cornell
Herbert Beebe                                   New Mexico State Univ (retired)
Niescja Turner                                  Florida Institute of Technology
Bidushi Bhattacharya                       Spitzer Science Center, Caltech
Paul Helfenstein                                Cornell University
David H. Smith                                  National Research Council
Howard Houben                                Bay Area Environmental Research Institute
Carrie Anderson                               New Mexico State University
Bernhard Schulz                               IPAC/Caltech
Scott Severson                                   UCO/Lick Observatory
Carl Grillmair                                   Spitzer Science Center
James Colbert                                    Spitzer Science Center
Thomas Jarrett                                  IPAC/Caltech
Reta Beebe                                         New Mexico State University
Oliver Hartmnann                             FU Berlin, Remote sensing of the earth and planets,
Melissa Nelson                                   University of New Mexico
Patrick Ogle                                       Spitzer Science Center
Larry Friesen                                    University of Houston at Clear Lake
Jeffrey Bary                                      University of Virginia
Roc Cutri                                           IPAC/Caltech
John McGraw                                   University of New Mexico
Paul Steffes                                        Georgia Institute of Technology
Paul Romani                                      NASA - Goddard Space Flight Center
W. David Carrier, III                       Lunar Geotechnical Institute
Stephen Shawl                                   University of Kansas
Regina Cody                                      NASA Goddard Space Flight Center
Thomas Kelsall                                  NASA/GSFC (ret.)
Stephen Baloga                                  Proxemy Research
Todd Clancy                                      Space Science Institute
Dennis Matson                                   JPL
Nicole Rappaport                              JPL
Barbara Anthony-Twarog               Univ. of Kansas
Bruce Twarog                                   University of Kansas
Bob Molloy                                        Spitzer Science Center/Caltech
Steve Bryson                                      NASA Ames
Gilbert Esquerdo                              Planetary Science Institute
Paul Abell                                          Planetary Science Institute
David Osip                                         Observatories of the Carnegie Institution of Washington
Kandis-Lea Jessup                            Southwest Research Institute
David Huestis                                     SRI International
Ray Russell                                        The Aersospace Corporation
Don Davis                                          Planetary Science Institute
Jim Thieman                                      NASA/GSFC
Samuel Dupree                                  Lockheed Martin Integrated Systems and Solutions
Amara Graps                                    INAF-Istituto di Fisica dello Spazio Interplanetario (IFSI)
Sze-leung Cheung                             Ho Koon Astronomical Center Hong Kong
Stefan Schroeder                               Max-Planck-Institut fuer Sonnensystemforschung
Pablo Gutierrez-Marques                MPS (Max Plancke Institute for Solar System Research)
Michael DiSanti                                 NASA-Goddard Space Flight Center
Sebastian Walter                               FU (The Freie Universit├Ąt), Berlin
Andrew Potter                                   National Solar Observatory
Irwin Shapiro                                    Harvard-Smithsonian Center for Astrophysics
Feng Tian                                           NPP (NASA Postdoctoral Program)
Douglas Caldwell                              SETI Institute
Patricio Rojo                                      Universidad de Chile, Astronomy Department

For those who have not seen it, here are links to my February 18, 2013, blog entry, “Responding to the IAU: Pluto and the Developing Landscape of Our Solar System.” This is a point-by-point rebuttal of the IAU’s statement justifying the 2006 vote, posted on its home page (Content is identical on both sites): and