Tuesday, August 7, 2018

Planetary Scientists Object to Use of Term "Planet 9" for Possible Objects Beyond Pluto

In the August 5, 2018, edition of Planetary Exploration Newsletter, a publication of the Planetary Science Institute, a group of planetary scientists expressed their objection to the insensitive use of the term "Planet Nine" to refer to one or more hypothetical planets beyond Pluto. Their statement points out that the IAU planet definition is "far from universally accepted," and adds that using the term "Planet Nine" for an object other than Pluto is disrespectful to the legacy of Clyde Tombaugh, who discovered Pluto, which is still viewed by many as the solar system's ninth planet.

Yes, according to those who hold to the geophysical planet definition, Pluto is actually the solar system's tenth planet rather than its ninth. This is because Ceres was not known to be spherical and therefore a small planet until it was observed with the Hubble Space Telescope. Now that we know Ceres is actually the solar system's fifth planet, this makes Jupiter its sixth, Saturn its seventh, Uranus its eighth, Neptune its ninth, Pluto its tenth, and so on. Unfortunately, Tombaugh did not live to see Ceres's upgrade, and for the better part of a century, Pluto was known as the solar system's ninth planet. While today that designation is more colloquial than scientific, even from a geophysical point of view, millions of people continue to see Pluto as planet nine. Personally, I like to call it "the ninth planet that is really the tenth planet."

On January 20, 2016, Mike Brown put out a press release announcing his theory of a hypothetical giant planet in the outer solar system and deliberately used the term "Planet Nine" in the title of the press release in an effort to establish this name universally. This was clearly the act of someone who is media savvy and understands public relations. He set out to establish a fait d'accompli that inherently endorsed his erroneous view that all or most planetary scientists accept the IAU designation and its corollary that the solar system has only eight planets. When I urged several media outlets to use the term "Planet X," the traditional term for a hypothesized but undiscovered world, they claimed the world already knows it as "Planet Nine" and would not know what was being referred to by the term "Planet X"--proving Brown's establishment of a self-fulfilling prophecy had worked--at least temporarily.

But two-and-a-half years later, his planet has yet to be found. And finally, planetary scientists are speaking up and appropriately requesting the use of a fair and balanced term instead of a loaded, biased one.

Here is the text of their petition, which can be found at https://planetarynews,org


We the undersigned wish to remind our colleagues that the IAU planet
definition adopted in 2006 has been controversial and is far from
universally accepted. Given this, and given the incredible
accomplishment of the discovery of Pluto, the harbinger of the solar
system's third zone - the Kuiper Belt - by planetary astronomer
Clyde W. Tombaugh in 1930, we the undersigned believe the use of the
term "Planet 9" for objects beyond Pluto is insensitive to Professor
Tombaugh's legacy.

We further believe the use of this term should be discontinued in favor
of culturally and taxonomically neutral terms for such planets, such as
Planet X, Planet Next, or Giant Planet Five.

Paul Abell
Michael Allison
Nadine Barlow
James Bauer
Gordon Bjoraker
Paul Byrne
Eric Christiansen
Rajani Dhingra
Timothy Dowling
David Dunham
Tony L. Farnham
Harold Geller
Alvero Gonzalez
David Grinspoon
Will Grundy
George Hindman
Kampalayya M. Hiremath
Brian Holler
Stephanie Jarmak
Martin Knapmeyer
Rosaly Lopes
Amy Lovell
Ralph McNutt
Phil Metzger
Sripada Murty
Michael Paul
Kirby Runyon
Ray Russell
John Stansberry
Alan Stern
Mike Summers
Henry Throop
Hal Weaver
Larry Wasserman
Sloane Wiktorowicz

Wednesday, May 30, 2018

Pluto is not a giant comet!

Within the past week, you may have seen reports of a study that some scientists say indicates Pluto is actually a giant comet that was formed by the aggregation of billions of comets. This is not true! What the study actually found is that both Sputnik Planitia, the left side of Pluto's heart feature, and Comet 67P/Churyumov-Gerasimenko, both were found to have the same isotope of nitrogen on their surfaces. While this is true and suggests they may originate in the same region of the solar system, it does not mean Pluto is a giant comet! In this case, people erroneously drew a conclusion without sufficient data to confirm that conclusion.

Below is a good article by planetary scientist Philip Metzger explaining why Pluto is not a giant comet.

Icy Worlds and Stars with Long Hair - Philip Metzger: Are icy worlds like Pluto just comets because they're made of ice? This post looks at what planets made of and looks at the amazing insides of icy worlds.

Saturday, May 26, 2018

Tom Siegfried, former editor of Science News: Pluto's Demotion Ignores Astronomical History

They keep on coming! Here is yet another terrific article about the issue of planet definition and the many problems with the 2006 IAU definition, this time by Tom Siefried, former editor of Science News.


Siegfried's article refers to a new scientific paper by Philip Metzger, Mark Sykes, Alan Stern, and Kirby Runyon, which can be found at https://arxiv.org/abs/1805.04115.