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Planet Again? Pluto, Most Moons Count Under Proposed Definition [Mar. 26th, 2017|12:46 am]

Please vote in the poll about Pluto's status that is embedded in this article!
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Pluto: Science has not spoken, and no one has to move on [Mar. 14th, 2017|10:22 pm]
The case for Pluto’s planethood is not at all grim—in spite of statements to that effect in articles published this month in the Australian-based publication Science Alert and in Forbes.com.

Both articles—the Forbes.com one by astrophysicist Ethan Siegel and the Science Alert one by writer Fiona MacDonald--are statements of interpretation rather than fact because they begin with a foregone conclusion that science somehow precludes Pluto—and dwarf planets in general—from being considered a subclass of planets.

This premise, written in wording that makes it appear to be factual rather than interpretive, is misleading and assumed to be true from the outset when this is hardly the case.

Consider the articles’ titles: Siegel writes “The Science Has Spoken: Pluto Will Never Be A Planet Again.” Using Siegel as an authority, MacDonald states, “An Astrophysicist Says Pluto Will Never Be A Planet Again, and We All Need to Move On.”

But science has not spoken. Ethan Siegal, one scientist whose field of study is not planets, has spoken and claimed to do so in the name of “science.”

And contrary to MacDonald’s claim, he hardly “penned a thorough takedown” of the argument for Pluto’s planethood.

Like most of the four percent of the IAU who voted for the controversial 2006 planet definition, Siegel is not a planetary scientist. His fields are galaxies and cosmology. This should not be at all understood as disrespectful to him. It just means he is not the go to person for determining what a planet is any more than Alan Stern is the go to person for defining the Big Bang.

In saying, “When it comes to planetary science, geophysics isn’t enough. In astronomy, the three rules of real estate also apply: location, location, location,” he self-identifies as a dynamicist. There is nothing wrong with that. What is wrong is his inherent assumption that his side of the planet definition debate is the only scientifically legitimate one, when this is not so.

The same is true for MacDonald’s statement that “trying to make it (Pluto) a planet again could hurt scientific progress going forward.”

Legitimate debates between those holding conflicting perspectives—in this case, dynamicists versus geophysicists—do not hurt scientific progress. What does hurt such progress is blind acceptance of one self-appointed group as the only “authority” on an issue.

In a February 20 article about the proposal for a geophysical planet definition being presented at the Lunar and Planetary Sciences Conference, writer(s) identified as BEC Crew state, “Of course, nothing changes until the IAU makes a decision…”

Therein lies the real problem. Such a claim amounts to circular reasoning: A thing is true because the IAU says it is true, with no room for anyone, including those who actually study planets, to legitimately disagree.

For geophysicists, an object’s intrinsic properties, not its location, take precedence when it comes to definition.

Siegel’s primary objection to the proposed geophysical definition is that it would make over 100 objects in the solar system, including moons and asteroids, planets. This objection is based largely on the notion that our solar system cannot have “too many planets,” that having a large number somehow devalues the term “planet.”

An understanding of the geophysical definition makes it clear that an asteroid can never be a planet and vice versa. If an object in hydrostatic equilibrium is classed as an asteroid, that classification is wrong. If an object classed as a moon is in hydrostatic equililbrium, it is both a moon and a (satellite) planet. The two are not mutually exclusive, and it remains perfectly fine to refer to such objects as moons. Also classing them as planets simply distinguishes these moons from those not large enough to be in hydrostatic equilibrium, such as Mars’ moons Deimos and Phobos.

Objections to more than a limited number of planets go back several centuries. Galileo’s reference to the four largest moons of Jupiter, which he discovered, as planets, raised major objections beginning with the church, whose position was there could only be seven perfect planets—the seven known since ancient times, which include the Sun and Moon but not the Earth.

When William Herschel discovered Uranus in 1781, his first instinct was to consider his discovery a comet, again due to the strong societal belief that no planets could exist beyond Saturn.

Contrary to Siegel’s claims, one can be honest and reject the notion that “there are very clearly eight objects that are different from all the others” in our solar system, as this is far from the case.

Earth actually has much more in common with Pluto than it does with Jupiter. Both Earth and Pluto have solid surfaces and are geologically layered into core, mantle, and crust; both have large moons formed via giant impact; both have nitrogen in their atmospheres; both have floating glaciers; both have volcanism, and like Earth, Pluto may harbor an ocean (though a subsurface one). In contrast, Jupiter is composed largely of hydrogen and helium, much like the Sun, and has no known solid surface. It has its own “mini solar system” of rings and moons. Putting Earth and Jupiter in the same category while excluding Pluto makes no sense.

Ceres, Jupiter’s moon Europa, Saturn’s moons Enceladus and Titan, Neptune’s moon Triton, and Pluto have different dynamics in terms of what and where they orbit, yet they all are similar in being “ocean worlds” with heat sources that allow for subsurface liquid water that could potentially be home to microbial life. Should these similarities in their intrinsic properties be rejected because their locations are different?

In terms of location, Pluto may well revolutionize our notion of what a star’s habitable zone is. No one expected a world orbiting so far from its star to be capable of hosting life, yet with an underground ocean, Pluto may do just that.

Even a rogue planet that orbits no star is still a planet based on its intrinsic properties.

Siegel cites dynamicist Jean Luc Margot’s 2015 schematic to emphasize a dividing line between planets and non-planets based on orbit clearing. However, Margot’s graph is clearly based on a 2002 paper by Alan Stern and Harold Levison that acknowledged a distinction between objects that gravitationally dominate their orbits and those that do not but never used that distinction to determine the latter are not planets.

Take a look at Margot’s graph, and notice the similarity to the one by Stern and Levison below it:

The scientific line between planetary (above) and non-planetary (below) status, for three definitions and a star equal to the mass of our Sun.

    Dynamical Dominance

With the exception of Eris, which had not yet been discovered when Stern and Levison’s paper was published, and the latter's inclusion of Earth's Moon, Margot’s dividing line is essentially the same as that of Stern and Levison, who designated objects above the line as “uber planets” and those below it as “unter planets” but never said the latter were not planets at all.

Scientifically, we can recognize this division without precluding those below the line from being considered planets. How? By recognizing that some planets gravitationally dominate their orbits while others do not. The former are called classical planets while the latter are called dwarf planets. Both, based on their intrinsic properties, fall under the broader umbrella of “planets.”

The IAU definition is insufficient in that it puts location over an object’s intrinsic properties. Maybe what we need is a planetary classification system that incorporates both intrinsic and extrinsic properties. Redesignating dwarf planets as a subclass of planets is an easy way to move in that direction. Some scientists have considered establishing a planetary classification system similar to the Herszprung Russell Diagram for stars or to the Star Trek system, that establishes multiple planet subcategories based on both an object’s intrinsic properties and location.

As for the hypothetical Planet X possibly lurking in the outer solar system, its discovery, mass, and orbital parameters do not change anything about Pluto or dwarf planets. Finding such a world would actually strengthen the position of those who recognize our solar system can and does have many planets.

Advocates of a geophysical planet definition do not need to “move on” or be patronized with statements telling them to do so.

All scientists—unless they just arrived from Vulcan—have biases and opinions. Good science is about acknowledging the difference between fact and interpretation, not imposing interpretation on the world and calling it fact. That is a disservice to everyone.
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Hope for Pluto—Should We Re-Redefine Planets? [Mar. 9th, 2017|12:07 am]
Hope for Pluto—Should We Re-Redefine Planets?
Planetary geologist Kirby Runyon is lead author of an abstract that proposes a new, geophysical definition of what a planet is.
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Another Voice for Pluto and the Geophysical Planet Definition: J. Richard Jacobs [Mar. 5th, 2017|10:23 pm]
Read J. Richard Jacobs' answer to If Pluto is not a planet, what is it? on Quora
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Today: Dr. Alan Stern on Weekly Space Hangout [Mar. 3rd, 2017|01:16 pm]

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Pluto and its moons: Findings from the New Horizons mission [Feb. 28th, 2017|03:24 pm]
Pluto and its moons: Findings from the New Horizons mission
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Pluto is still a planet, and geophysical planet definition proposal is not a "non-starter" [Feb. 23rd, 2017|08:15 pm]
Pluto and Charon

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.
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87 Years of Pluto: Complete List of Signatories Who Signed 2006 Petition Rejecting IAU Definition [Feb. 18th, 2017|07:06 pm]
Pluto Discovery Cartoon
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 http://www.ipetitions.com/petition/planetprotest/ . 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
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.
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, Geosciences
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 Universität), 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): http://laurele.livejournal.com/2013/02/18/ and http://laurelsplutoblog.blogspot.com/2013/02/responding-to-iau-pluto-and-developing.html
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Six New Horizons scientists propose geophysical planet definition [Feb. 8th, 2017|12:09 pm]
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New Horizons video simulates Pluto landing; Charon had icy tectonic plates [Jan. 30th, 2017|01:07 am]
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