After
the 1920s debate over whether the universe is composed of one galaxy—the Milky
Way—or of many galaxies was resolved with definitive evidence for the latter
position, the controversy was resolved.
Our
universe contains billions of galaxies, including structures once referred to
as “spiral nebulae” erroneously thought to be located within the Milky Way.
After
observations conducted during the May 1919 total solar eclipse confirmed
Einstein’s theory of general relativity, showing the position of stars near the
Sun slightly shifted from their actual locations, general relativity was
accepted worldwide as being true—and as the reason for the strange precession
of the planet Mercury’s perihelion (point closest to the Sun).
But
ten years after the controversial and highly problematic planet definition
adopted by four percent of the IAU, most of whom were not planetary scientists
but other types of astronomers—that definition remains as contested as it was
on day one.
Rather
than bringing a resolution to the debate, as did the evidence in the two
previous examples, the IAU vote heightened that debate and resolved nothing.
It
actually did harm to science by confusing the public into thinking science is
done by voting and by imposing a definition that contradicts everything people
see when observing close-up photos of Pluto.
Back
in 2006, no such close-ups of Pluto existed. However, the IAU knew fully well
that the New Horizons probe, launched seven months before that year’s General
Assembly, was on its way to Pluto and would provide a wealth of images and data
in July 2015.
They
also knew that the Dawn mission was scheduled for a launch the following year,
and it would visit Ceres and Vesta, two objects that orbit between Mars and
Jupiter, both of whose statuses as asteroids were questionable.
The scientifically
correct action would have been to wait until the data from these missions came
in before trying to classify objects no one ever viewed as more than tiny dots.
Unfortunately,
several astronomers, motivated by their own personal agendas, did not want to
wait for the results. Leading that group was the late Dr. Brian Marsden, who
had expressed his desire to see Pluto demoted from planethood to discoverer
Clyde Tombaugh back in 1980.
When
a team of three astronomers discovered a planet beyond Pluto initially thought
to be bigger than Pluto, now known as Eris, some of these astronomers jumped at
the opportunity to use the discovery as a means of imposing their agenda.
They
claimed that if the new object is larger than Pluto and yet is not a planet,
then Pluto could not be a planet either.
In
2010, when Eris occulted a star, a different group of astronomers led by Dr.
Bruno Sicardy determined it is marginally smaller than Pluto though 27 percent
more massive.
Even
if Eris were larger than Pluto, why would its discovery prompt any sense of necessity
to come up with a specific definition of planet? So what if our solar system
has 10 planets or 11, or 50? Most people actually find it exciting to learn
that the solar system has many more planets than anyone ever thought.
What
should have happened is that Eris should simply have been added as yet another
solar system planet.
But
in addition to personal agendas, some astronomers came up with the ridiculous
idea that our solar system cannot have “too many planets” because kids won’t be
able to memorize all their names.
That
argument is no more rational than stating we have to limit the number of stars
and galaxies to something countable, or that we have to limit Jupiter’s moons
to four because no one can memorize the names of 67.
Memorization
is not critical to learning. Once upon a time, little was known about the
planets other than their names, their order from the Sun, and estimates of
their sizes. At that point, there wasn’t
much else to teach about them.
Today,
things couldn’t be more different. With the dawn of the space age, we have
robotically visited every single one of the nine classical planets as well as
Ceres and Vesta. We know the complex processes many of them and many of their
moons undergo, their compositions, and their surface features.
Instead
of asking children—and adults—to memorize a list of names, we can teach them
the characteristics of the different subclasses of planets such as
terrestrials, gas giants, ice giants, dwarf planets, proto-planets, super
Earths, hot Jupiters, hot Neptunes, etc.
The
latter three are not present in our solar system but do exist in other star
systems.
Ten
years ago, in essence, the IAU concocted a reason to issue a decree that was
never needed. Its members then set out to craft a definition that achieved the
results they desired, namely excluding Pluto.
And
they established a definition with a requirement that set Pluto’s status in
stone. No matter what would be discovered by New Horizons, Pluto could never
again be a planet because its intrinsic characteristics meant nothing. The only
thing that counted was whether it cleared its orbit.
Orbit
clearing may be useful in terms of understanding the effects celestial objects
have on other objects, but making it a requirement for planet status makes
absolutely no sense.
The
further an object orbits from its parent star, the larger an orbit it has to
clear. That makes the definition inherently biased against planets in distant
orbits from their stars.
Furthermore,
it perpetuates an erroneous conception of objects like Pluto and Ceres, leading
people to think these worlds are surrounded by numerous objects in their orbits
in an asteroid field similar to the one through which Luke Skywalker piloted
the Millennium Falcon in Star Wars.
Yet
nothing could be further from the truth. Both the asteroid and Kuiper belts are
huge, with vast distances between objects residing in them. This is why New
Horizons did not have to use one of its contingent trajectories to fly through
the Pluto system. Those trajectories were based on a need to avoid debris that
might be floating around near Pluto.
But
there was no such debris, which New Horizons scientists attribute to Pluto’s
large moon and binary companion Charon having swept it all from the system.
If
KBOs were really so close to one another in a crowded belt, why could only the
Hubble Space Telescope find a few close enough KBOs in New Horizons’ path for a
visit after Pluto? From the way people talk about the Kuiper Belt, one would have
thought there were numerous small objects nearby.
Haumea,
Makemake, Eris, and other, more recently discovered dwarf planets are not in
Pluto’s orbit unless one counts the entire Kuiper Belt as part of Pluto’s orbit—a
proposition that makes no sense, as the belt is huge, and the majority of it is
located well beyond Pluto.
Yet,
because of the IAU definition, many people are under the misconception that
many objects larger than Pluto have been discovered in the Kuiper Belt and that
the entire region is a zone crowded with ice balls and rocks.
While
there could be planets larger than Pluto out there, so far none has been
discovered.
Astronomer
Mike Brown, who co-discovered Eris, earlier this year publicly hypothesized the
existence of a large planet far beyond Pluto, which, to add insult to injury,
he deliberately referred to as “Planet Nine,” clearly for no other reason than
to snub those who still consider Pluto a planet.
Now,
when we have a wealth of data and images about Pluto, certainly sufficient new
information to re-open the planet debate yet again, the IAU has no interest in
doing so. Why does some new data in 2006 justify IAU action yet a huge
inundation of new information in 2016 not inspire similar action?
It
is not just the IAU that is at fault here. The media has been misrepresenting
this issue for a decade now. From day one, they should have questioned the IAU
definition and consulted the many planetary scientists who signed a petition
disagreeing with it. Instead, they reported the decision as fact, calling Pluto
an “ex-planet,” and stating that textbooks and teachers now have to change
their teaching of the solar system to one of eight planets.
The
media also unprofessionally blindly accepted Brown’s use of the term “Planet
Nine” for the hypothesized large planet yet to be discovered when what they
should have done is referred to it by the standard appellation for undiscovered
worlds, which is “Planet X.”
Where
the media failed big time is in accepting the IAU decree at face value instead
of critically pointing out that science is not determined by “authority” but by
a preponderance of evidence for a theory or position.
They
also failed to inform the public that most of the 424 IAU members who voted in
2006 were specialists not in planetary science but in completely different
fields of astronomy. Why would a person who studies black holes be considered
an expert on planetary science? Would the media accept a decree by planetary
scientists about the nature of black holes?
The
fact that the IAU definition is still so contentious a decade after its
adoption is itself evidence that it was and is an epic fail.
Interestingly,
even children born after the vote still consider Pluto a planet. When I worked
as a performer in the New Jersey Renaissance Faire playing a court
astronomer/astrologer, I asked children what their favorite planet was, and
Pluto was the number one answer, followed by Earth.
That
is usually when I shared that in the 1560s, calling Earth a planet was
considered controversial, as it amounted to an affirmation of Copernicanism,
which stated the Sun is the center of the solar system and the Earth simply a
planet orbiting the Sun.
New
Horizons Principal Investigator Alan Stern reports that the status issue is
raised at every single talk he gives about New Horizons and Pluto, even if he
does not mention the controversy in his presentation.
Because
planetary scientists do not have a formal organization like the IAU, they do
not have a means to organize and promote an alternative point of view. That,
however, does not mean that that alternative view does not exist.
As
for the claim that Pluto cannot be considered a “major planet” due to its small
size, the real problem is the false dichotomy inherent in using the terms “major”
and “minor” planet. As David Weintraub notes in his book Is Pluto A Planet, the term “minor planet” has been used for more
than a century to refer to asteroids and comets, objects too small to be
rounded by their own gravity. These are the objects the IAU accurately refers
to as “Small Solar System Bodies.”
But
Pluto and Ceres—and all dwarf planets—are not asteroids, so the term “minor
planet” is not appropriate for them. A better schematic is to do away with the
terms “major” and “minor” planet altogether and replace them with terrestrials,
jovians, and dwarf planets, all of which fall under the umbrella of planets.
Objects like Vesta and Pallas, which are larger and more complex than
asteroids, could comprise yet another planetary subcategory, “proto-planets.”
A
decade after a controversial vote allegedly changed everything about the way we
understand our solar system but really changed nothing, planetary scientists, professional
and amateur astronomers, and members of the public overwhelmingly continue to
view Pluto as a planet, especially in light of the geologically complex world
New Horizons found.
Public
usage, not a decree from an isolated, self-appointed group of “experts,” will
determine which view enters into posterity. From the last ten years, it is
clear that when it comes to Pluto, that view will not be the one advocated by
four percent of the IAU.
Adored
worldwide, the little planet that would not die is so very special that it will
be there for eternity.
