This is a blog advocating the overturning and/or ignoring of the controversial IAU planet definition that demoted Pluto, the adoption of a broader planet definition that includes all dwarf planets, and the chronicling of worldwide efforts toward these goals.
We
have once again reached that noteworthy milestone—in the Northern Hemisphere,
it is the Winter Solstice, the shortest day and longest night, the turning
point of the year when darkness stops advancing, and the Sun appears to stand
still in the sky before reversing course.
It’s
been quite a year for space exploration. The James Webb Space Telescope
successfully launched just about a year ago in spite of endless delays and
repeatedly going over budget. It performed flawlessly in unfurling its
sunshield and mirror, reaching its Lagrange Point position, and returning
stunning images that open a new era of exploration for astrophysics, planetary
science, and cosmology.
Another
long delayed project, our return to the Moon, also finally launched this year.
Artemis I sent back beautiful close up photos of both Earth and Moon,
reminiscent of the famous Apollo 8 image captured at this time of year back in
1968—a picture that had a profound impact on many and played a key role in
launching the environmental movement.
While
2022 has certainly had its share of challenges, it brought to fruition projects
some doubted would ever launch, revealing that late does not mean never and
reminding us that if something really matters, giving up should never be an
option.
People
who have had the good fortune to travel to space note it brings a life-changing
perspective. From there, no borders are visible, just one fragile planet, now
home to 8 billion people and numerous other life forms.
We
all, not just world leaders, need that change in perspective because the
problems our home planet faces cannot be addressed by just one group of people
or one country. The only way we have any hope to stabilize our climate,
mitigate the worst effects of climate change, and clean up our air, land, and
water, is to come together as one people on one planet.
Too
often, people look at the year-end holidays in ways that divide us, at a time
when, more than ever, we need to unite to preserve our planet’s habitability
for future generations—so we can one day explore the solar system and
eventually the stars.
This day, at its core, is about hope. It is about light and life, known by the
Romans as the Birthday of the Unconquerable Sun. This makes it an ideal time to
treasure the gift of our planet and affirm the amazing things we can accomplish
when we come together for a common goal—like launching JWST and sending
astronauts to the Moon.
If
we can do those things, we can save our planet for future generations. May the
year that starts with the return of the light inspire us all to come together
and choose a future of light and life.
Space.com is usually a very
credible information site about all matters space and astronomy, which is why
its October 23, 2022 article, “Why
is Pluto Not a Planet?” is so disappointing in its blatant one-sidedness.
More
than 16 years after the controversial IAU vote on a highly flawed planet
definition, it is difficult to understand why this site would publish an
article that is extremely selective in every one of the sources it uses as
references. From the IAU web page to Mike Brown to Ethan Siegel, formerly of Forbes, to a Neil Tyson video, the
article refers almost solely to supporters of the IAU definition and completely
excludes the many essays and articles written from the opposing point of view.
The
article is problematic starting with its title, which, instead of acknowledging
the ongoing debate over planet definition and Pluto’s status, simply states the
IAU view as fact. This misleading title essentially presents the IAU view as “the
truth” rather than as one view in an ongoing debate, and this notion is
repeatedly assumed in the article, in spite of very sparse references to
dissenting views.
Yet,
there is absolutely NO reason to give the IAU position privilege as somehow being
the “official” one in use. It is simply one of several definitions currently
used by planetary scientists.
We need
to address the factual errors in this article. Like many writings on this
subject over the last 16 years, the writers cite Ceres’s discovery as a planet
and subsequent demotion to asteroid in the mid-19th century as an
earlier example of what happened to Pluto. However, they fail to acknowledge
the other, crucial part of Ceres’s history.
Because
it is very small, Ceres could not be resolved into a disk by 19th century
telescopes. At the time, it therefore made sense to demote it to one of many
asteroids in the belt between Mars and Jupiter. However, since then, Ceres has
been found to be spherical, meaning unlike nearly every asteroid in that belt,
it is squeezed into a round or nearly round shape by its own gravity. Most
asteroids are simply rubble piles shaped by chemical bonds. The threshold for
an object being spherical, in a state known as hydrostatic equilibrium, is crucial
because this is when objects begin to experience geology and the complex
processes seen on rocky planets.
In 2015, NASA’s Dawn mission revealed
Ceres to have these complex features, including cryo-volcanoes and a possible
subsurface ocean that could potentially host microbial life. These findings
indicate the 19th century demotion was in error and that Ceres is
more like the larger rocky planets than almost all objects in the asteroid
belt, with the exception of Vesta and Pallas, which appear to have once been
spherical only to have had a large portion knocked off during impacts with
other objects.
Many
scientists argue this makes Vesta and Pallas deserve an intermediate category
between asteroid and small or dwarf planet, such as protoplanet. In fact, some
scientists on the Dawn mission refer
to Vesta as the solar system’s “smallest terrestrial planet.”
While
some, including the writers of this article, invoke Pluto’s eccentric orbit and
17-degree tilt to the ecliptic as reasons for demoting it from planethood, the
fact is several exoplanet systems contain multiple giant planets all orbiting
in different planes. At least two systems have giant planets that cross one
another’s orbits. And the ecliptic, often wrongly depicted as the path of the
Sun, is actually the plane of the Earth in its solar orbit. Requiring objects
to orbit in the same plane as Earth is a violation of the Copernican principle,
which essentially states that Earth is just another planet, not the center of
anything. And if giant objects that cross the orbits of other giant planets in
their systems are not planets, what then are they?
The
next inaccuracy in the Space.com
article is its attribution of Eris’s discovery solely to Mike Brown. While
Brown often presents himself as Eris’s sole discoverer, the fact is, Eris was
discovered by a team of three scientists, the other two being Chad Trujillo and
David Rabinowitz. Significantly, both Trujillo and Rabinowitz reject the IAU
planet definition. Rabinowitz even signed a petition with hundreds of planetary
scientists back in 2006 in response to the IAU definition, saying they would
not use it.
The
reference to the late Brian Marsden is also problematic, as Marsden, who apparently
had a long feud with the late Pluto discoverer Clyde Tombaugh, was obsessed for
decades with demoting Pluto so it could be put under his auspices at the IAU
Minor Planet Center. Like Brown, he is a scientist who appears to have had his
own agenda from the start.
While
the article does acknowledge that only 424 IAU members voted on the controversial
planet definition in 2006, it fails to note that this vote was held in
violation of IAU bylaws, which prohibit putting a resolution to the floor of a
General Assembly without first vetting it by the proper IAU committee. It also
fails to mention that these 424 people were largely not planetary scientists
but other types of astronomers, that they represented only four percent of the
IAU’s membership, that no electronic or absentee voting was permitted, that 91
of the 424 voted for dwarf planets to be classed as a subclass of planets, and
that an equal number of professional planetary scientists signed the afore-mentioned
petition rejecting the IAU definition within days of its adoption.
Additionally,
the writers fail to mention that when initially coined by Alan Stern in 1991,
the term “dwarf planet” was intended to designate an additional class of small
planets, not to designate a class of non-planets. In its unauthorized vote, the
IAU essentially misused the term “dwarf planet” based on the fiction that dwarf
planets are fundamentally different compositionally than their larger
counterparts, a position proved false by the findings of the Dawn and New Horizons missions.
Even Neil Tyson is on record saying he has no problem with dwarf planets being
considered a subclass of full planets!
As
the article writers note, New Horizons found Pluto to have active geology;
diverse features including windswept dunes, varied terrains, a layered
atmosphere, cryo-volcanism, interaction between atmosphere and surface, and a
likely subsurface ocean. Some complex features discovered on Pluto exist
elsewhere in the solar system only on Earth and Mars!
To
make matters worse, the article never acknowledges the alternative geophysical
planet definition, which is preferred by most planetary scientists, beyond a
vague mention of a 2017 proposal that “defined a planet as a round object in
space that’s smaller than a star.” This is a major disservice to the proposal,
presented to the Lunar and Planetary
Science Conference that year, which centers planet definition on an object’s
intrinsic properties rather than on its location, which the IAU definition does.
Most
problematic is the article’s inherent assumption that only the IAU has the
ability or power to determine what a planet is. Conveyed throughout this
article, that sentiment can be seen in the statement noting Alan Stern and
David Grinspoon’s 2018 Washington
Post article urging reconsideration of planet definition “have fallen
on deaf ears so far, and it seems unlikely theIAU
will revisit the controversy any time soon.”
If such pleas to the IAU fall on deaf ears, and the organization refuses to
address new data returned by the Dawn
and New Horizons missions, then it is
time to consider other venues for this discussion. The notion of science being
decided by any type of “authority” went out with Galileo’s discovery of Jupiter’s
moons over 400 years ago. A science publication like Space.com should know better than to appeal to any “authority”
regarding scientific matters.
Finally,
the article falls back on attributing opposition to the IAU decision to
emotion, as seen in its Mike Brown quote, “Nostalgia for Pluto is not a very
good argument, but that’s basically all there is. Now, let’s get on with
reality.”
This comment is not only demeaning; it is also blatantly false. Scientists,
amateur astronomers, and members of the public oppose the IAU definition not
because of nostalgia or emotion but because the geophysical definition, which
classifies objects first and foremost by their intrinsic properties, simply
makes more sense based on what we have discovered about these objects. Brown
does not get to unilaterally end the debate and get the last word simply
because he wants to do so.
There are so many scientists and publications that articulately present the
other side of this debate. I urge Space.com
to do a better job in presenting this fascinating controversy to give readers a
comprehensive understanding of both positions, allowing them to decide for
themselves where they stand.
The
authors of this article are right on one thing: This debate will continue for the foreseeable
future.
Sources in response to those presented
in the Space.com article:
Note: I wrote the response to the IAU statement and to Siegel’s Forbes article and embrace my role in
this debate on Twitter with the handle @plutosavior
.
I have covered the New Horizons mission for the website Spaceflight Insider
since 2014 though the opinion expressed here is solely my own and not
necessarily that of the site or its editors.
“Responding
to the IAU: Pluto and the Developing Landscape of the Solar System,” a
point-by-point rebuttal to the IAU statement:
Sixteen
years. As of today, that is how long it has been since the IAU attempted to end the planet definition
debate once and for all but instead created more chaos and confusion on this
topic for the media, educators, and the general population.
The
spread of misinformation their decision caused unfortunately continues to this
day.
In
the last few years, some people have taken to designating August 24, the day of
the IAU vote, as a “holiday” titled “Pluto Demoted Day.” Writer Aryan Sahu, in
a very one-sided article published on the website Merazone,
actually described this day as “fun” and listed ways to “celebrate” it without
even acknowledging the ongoing controversy. Unfortunately, the usually
informative astronomy site TimeandDate.com also lists this day
as a “fun holiday.”
But
it is not in any way a holiday or something to celebrate.
I instead choose to call it Pluto
Resistance Day. It’s the day when all who recognize the flaws of the IAU
definition come together and affirm our commitment to advocate for a better
planet definition in the long term and educate the public about the ongoing
debate in the meantime.
Although
there are good children’s books on the solar system that present both sides of
the controversy, others that ignore the pro-Pluto view continue to be published.
I cringed when I saw one new children’s book titled Eight Little Planets and another called How to Teach Grownups about Pluto that humorously teaches children
to use the five stages of grief to get the adults in their lives to accept that
Pluto is “gone.”
Yet there is no need for any type of grief because Planet Pluto is alive and
well!
But
the misinformation continues. Just today, an article in The
Abbotsford News erroneously describes Pluto as an “icy stone plodding
around the Kuiper Belt,” then states that “Thousands of objects have been
catalogued so far in that outer belt, the Kuiper Belt, and at least 200 of them are bigger than Pluto.”
Far
from an “icy stone,” Pluto is approximately 70 percent rock. And not a single
object larger than Pluto has been discovered in the Kuiper Belt to date. Eris
was initially thought to be larger but was found to be marginally smaller than
Pluto when a team of astronomers observed it occult a star in 2010.
Yesterday,
an article published in Science News
titled "The
Discovery of the Kuiper Belt revamped our view of the solar system"
failed to even acknowledge the ongoing planet debate, quoting Mike Brown, David
Jewitt, and Jane Luu, all of whom argued that Pluto “does not belong with the
planets” without interviewing or mentioning a single planetary scientist who
disagrees with this statement and favors the geophysical definition. The
geophysical definition was not even mentioned once in the article.
It then goes on to say, "Pluto probably wouldn't be a member of the planet
club much longer, the two (Jewitt and Luu) predicted. Indeed, by 2006, it was
out” with no acknowledgement of the fact that most of the four percent of the
IAU who voted on this were not planetary scientists but other types of
astronomers, that an equal number of planetary scientists signed a petition
rejecting the IAU decision, and that most planetary scientists today ignore
that definition in favor of the geophysical one.
As noted before in this blog, the IAU definition requires a planet to orbit the
Sun, not a star. This means that none of the 5,000 plus exoplanets discovered
to date count as planets under their definition. Neither do rogue planets,
which don’t orbit any star and therefore have no orbit to clear. In 2006, the
IAU leadership promised to address the issue of defining exoplanets, but in 16
years, no such effort has been made.
Meanwhile,
seven years have passed since Dawn’s
flyby of Ceres and New Horizons’ flyby of Pluto, and the IAU
has not shown any interest in using the data from these missions to reconsider
the status of Ceres, Pluto, and other dwarf planets that could potentially have
subsurface oceans capable of harboring microbial life.
Just
two weeks ago, the IAU held yet another General Assembly that didn’t consider
any of these issues.
While
the stalemate continues over planet definition and the IAU continues to do
nothing to correct the confusion their definition has caused, there has been
one major positive development in the last year. Over budget and more than a
decade late, the James Webb Space Telescope (JWST) finally and successfully launched
in the last week of 2021.
On
several occasions, JWST was almost
canceled and/or defunded. Some astronomers even argued the project was not
worth the trouble and expense. And even after launch, so many parts had to work
correctly that many scientists felt genuine trepidation, afraid something would
go wrong.
But
nothing did, and today, JWST is
orbiting the Sun one million miles from Earth and taking unprecedented,
breathtaking photos of galaxies, stars, and planets. It just sent back a
gorgeous image of Jupiter, and I know I’m not alone in hoping it one day images
Pluto as well.
Whether with JWST or another
observatory, it is only a matter of time before we discover dwarf exoplanets the
size of Pluto. Will that discovery have any impact on the IAU?
JWST took much longer to launch than
expected and faced numerous obstacles, including hurricanes and earthquakes,
yet it is now giving us a whole new view of the universe. And one of its
lessons is that good things sometimes take much longer than anyone desired or
anticipated. But late does not mean never.
No
matter how long it takes, we will not give up on a better, more inclusive
planet definition that recognizes dwarf planets as a subclass of planets. We
will NEVER go away. One way or another, the travesty of August 24, 2006, will
be undone. In the meantime, we will continue to inform the media, textbook
publishers, educators, and the general public that the debate continues, that
the geophysical definition is the one preferred by most planetary scientists,
and that the IAU definition is just one of many, not in any way more “official”
or legitimate than any others in use.
For those
interested in reading a very fair and balanced account of the history and
current state of the planet definition debate, writer Matt Williams has published
an excellent article on the website Interesting
Engineering, which includes quotes by Alan Stern, Phil Metzger, and
yours truly. I am very grateful to him for giving me a voice in his
comprehensive article and encourage all Pluto fans and those interested in this
issue to give the article a read.
I am a freelance writer and community activist who has worked on many progressive and Democratic political campaigns over the last 25 plus years and a lifelong resident of Highland Park, NJ. I have a BA in Journalism from Rutgers University, an MA in Middle East Studies from Harvard University, and an MEd in English Education from Rutgers Graduate School of Education. An enthusiastic amateur astronomer, I have just completed Swinburne University Astronomy Online's Graduate Certificate of Science in astronomy and am pursuing a Masters of Science in astronomy at Swinburne. I am also an actress with experience in theatre and film and have written a full length play. I am currently working full time on a book "The Little Planet That Would Not Die: Pluto's Story."
