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Thursday, December 21, 2017

The Winter Solstice

Four months ago, Americans watched in wonder as a total solar eclipse traversed the nation, and, as many described, “turned day into night.” To many who experienced it, the eclipse was a sublime, even spiritual experience beyond anything words can describe.

Every year during the autumn, day, at least in some sense, turns to night, as the Sun sets earlier and earlier, to the point where, as I often note in frustration, “It gets dark in the middle of the day.” We know this is natural, that it is part of an annual cycle, yet it inspires a range and depth of emotions, from sadness to fear and for some, even fascination.

Those who spend time outdoors during this period can sense the Earth going to sleep and see what is left of life being pulled back into her.

The Winter Solstice, at its core, is about hope. What looks like death is just a period of dormancy. Nature needs the power to restart, and the great generator we call the Sun begins recharging on this day, slowly growing in strength until it opens the slumbering seeds underground and warms the Earth’s frozen surface, drawing the baby plants out into the light.

In an email message today, Sarah Rasmussen of Greenpeace wrote, “There is so much darkness in our world right now, from environmental disasters to climate change…But light is coming to push out the darkness, and we are fighting as hard as we can to ensure that it shines where it will do the most good…The darkest hour is just before the dawn.”

In the natural world, all the major action at the Winter Solstice is beneath the surface, unseen. It isn’t obvious. It can only be felt. Yet this invisible miracle, which from our perspective happens solely because we live on a planet with a 23.5 degree axial tilt, is as real, as profound, as intense as anything can be.

These words, put as a voiceover to a Gaelic version of “Silent Night” by Enya, capture the awe and wonder of this day.

“Yule—the Winter Solstice
Cold and bleak—
The longest night of the year
Though we are in darkness,
We know the Winter Solstice is near.
We light up the long nights with candlelight and evergreens.
We deck the halls with beautiful things.
The Earth is in a deep slumber…
The light is growing dimmer…
But, almost unnoticed,
The Solstice brings its miracle.
There is stillness,
Beautiful and serene…
Peacefully, quietly, the Sun is reborn.
In this small, still moment, the light returns again,
The promise kept
That death is not the end.
From this day, forward, the light and the warmth grow stronger.
But we remember this moment that brings the greatest gift of all.
The light brings with it not only the promise of rebirth,
But (the knowledge that) even in our darkest hour,
The light will always return.
It is the spirit of goodwill,
The warmth of our hearts.
It is peace and joy
That bring us out of the dark.
Give freely of yourself;
Help someone in need;
Bring light to the darkness.
Give hope, and offer peace.
Sending you warm tidings this Yule season.
May your biggest wishes come true!
Eat, drink, and be merry!
A blessed and happy Solstice to you!”

Enya, “Yule, The Winter Solstice,”

It isn’t over. Darkness hasn’t won.

Keep hope alive!

Saturday, November 18, 2017

Help Nickname New Horizons' Second Target

NASA's New Horizons mission to Pluto and the Kuiper Belt is looking for your ideas on what to informally name its next flyby destination, a billion miles (1.6 billion kilometers) past Pluto.

On New Year's Day 2019, the New Horizons spacecraft will fly past a small, frozen world in the Kuiper Belt, at the outer edge of our solar system. The target Kuiper Belt object (KBO) currently goes by the official designation "(486958) 2014 MU69." NASA and the New Horizons team are asking the public for help in giving "MU69" a nickname to use for this exploration target.

"New Horizons made history two years ago with the first close-up look at Pluto, and is now on course for the farthest planetary encounter in the history of spaceflight," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate in Washington. "We're pleased to bring the public along on this exciting mission of discovery."

After the flyby, NASA and the New Horizons project plan to choose a formal name to submit to the International Astronomical Union, based in part on whether MU69 is found to be a single body, a binary pair, or perhaps a system of multiple objects. The chosen nickname will be used in the interim.
"New Horizons has always been about pure exploration, shedding light on new worlds like we've never seen before," said Alan Stern, New Horizons principal investigator from Southwest Research Institute in Boulder, Colorado.

"Our close encounter with MU69 adds another chapter to this mission's remarkable story. We're excited for the public to help us pick a nickname for our target that captures the excitement of the flyby and awe and inspiration of exploring this new and record-distant body in space."

The naming campaign is hosted by the SETI Institute of Mountain View, California, and led by Mark Showalter, an institute fellow and member of the New Horizons science team. The website includes names currently under consideration; site visitors can vote for their favorites or nominate names they think should be added to the ballot. "The campaign is open to everyone," Showalter said. "We are hoping that somebody out there proposes the perfect, inspiring name for MU69."

The campaign will close at 3 p.m. EST/noon PST on Dec. 1. NASA and the New Horizons team will review the top vote-getters and announce their selection in early January.

Telescopic observations of MU69, which is more than 4 billion miles (6.5 billion kilometers) from Earth, hint at the Kuiper Belt object being either a binary orbiting pair or a contact (stuck together) pair of nearly like-sized bodies – meaning the team might actually need two or more temporary tags for its target.

"Many Kuiper Belt Objects have had informal names at first, before a formal name was proposed. After the flyby, once we know a lot more about this intriguing world, we and NASA will work with the International Astronomical Union to assign a formal name to MU69," Showalter said. "Until then, we're excited to bring people into the mission and share in what will be an amazing flyby on New Year's Eve and New Year's Day, 2019!"

To submit your suggested names and to vote for your favorites, go to:

Media Contacts:
Rebecca McDonald, SETI Institute
(650) 960 4526,
Michael Buckley, Johns Hopkins Applied Physics Laboratory
(240) 228-7536,
Laurie Cantillo, NASA Headquarters
(202) 358-1077,

Atmospheric haze makes Pluto colder than previously thought

Atmospheric haze makes Pluto colder than previously thought

Thursday, August 24, 2017

Eclipsing the IAU

This year, the anniversary of the disastrous IAU planet definition vote that continues to cause confusion and misconceptions among the public has gone largely unnoticed—probably because three days ago, a total solar eclipse mesmerized thousands if not millions across the North American continent, and both pictures and accounts of that event are still being actively shared online.

The fact that so many people viewed the solar eclipse, whether in person or online, illustrates that the general public can, under the right circumstances, become excited about astronomy. Though not to the same extent, space missions such as Cassini at Saturn and Juno at Jupiter or the various rovers on Mars generate similar enthusiasm and attention if they are given appropriate media attention.

Two years ago, the New Horizons flyby generated the same kind of fascination with Pluto. People are naturally inspired by the solar system and exploration of its many worlds.

Astronomers, both amateur and professional, should be encouraging this kind of excitement, should want to share the wonders of the sky with the public.

In 2006, four percent of the IAU did the exact opposite. They decreed that they and only they can determine the identity of celestial objects, as if they somehow own these objects. Reaction to their decision was justifiably negative because that decision amounted to rejection of any cultural or popular conception of the solar system. Inherent in the message of the vote was the statement, the solar system is not yours. An object that looks and acts like a planet isn’t really a planet for some obscure reason no one really understands.

Keep things simple; keep the number of planets small. That was the real motivation behind the decision of August 24, 2006. And its message to the public was, when it comes to science, your views and understanding of the solar system mean nothing.

In his book Century’s End, author Hillel Schwartz discusses a controversy that has reared its head at the end of every century for 500-1,000 years. Does the new century start in the year 00 or 01?

There can actually be no correct answer to this question because the dating system we use is based on a mathematical error. It is a number line with numbers going from negative to positive but without the zero such a number line requires. The concept of the zero was unknown to the sixth-century monk who created the system.

Ordinarily, the first century would be the years 0-99, the second century the years 100-199, etc. But because the system has no zero, the first century, to have a total of 100 years, is actually the years 1-100, the second 101-200, etc. That is counterintuitive, as it tells us that the year 2000 is actually part of the old rather than the new century.

An interesting pattern developed over the last few hundred years. “Elites” such as scholars and intellectuals, advocated the counterintuitive method, the one viewed as requiring complex thinking rather than the popular conception. These people always insisted on centuries starting in the 01 year. In Boston, they refused to celebrate the beginning of the 20th century in 1900, then threw a grand public celebration in 1901.

In contrast, the general public went with the view that inherently sounded correct. They considered 1900 the beginning of the 20th century and 2000 the beginning of the 21st century.

The point here is a cultural one. The real issue at hand was the division between the “elites” and the common people. Anyone who wanted to sound educated or intellectual usually went with the counterintuitive 01 option, which supposedly showed they understood the complexity of the situation.

In reality, there can be no answer to this dilemma because the dating system is based on a mathematical error. Neither view is correct. This is why NASA, in its pages listing 5,000 years of solar and lunar eclipses, adds a zero to the count, assigning zero to the year 1 BCE, 1 to the year 2 BCE, etc. Predicting eclipses could not be done using an incorrect number line.

A similar phenomenon has happened regarding Pluto. Most members of the public grew up with Pluto being classed as a planet, and in the absence of a logical reason to change that, continue to consider it one. In contrast, those who want to seem intellectual or professional often adopt the other view, supposedly counterintuitive one. To them, “simple” people view Pluto as a planet while those who are more educated and intellectual understand the complexity of the issue and agree with the “experts” after understanding their line of thinking.

In other words, rejecting the “common” view supporting Pluto’s planethood has for some become a status symbol, a way of supposedly distinguishing themselves from the masses and showing they know more than the average person.

This is a psychological and cultural issue. It is not science, and it is bunk.

Eleven years after the vote on what the IAU has turned into a dogma they refuse to ever reconsider, the reality is many top planetary scientists in the world view Pluto as a planet. New Horizons sent back data showing Pluto to be a world that looks and acts like a planet. “Science” does not in any way support designating Pluto as anything else.

The August 21 solar eclipse showed the public enjoys engaging in astronomy and can be motivated to do so with appropriate outreach and education that brings people in rather than keeps them out.

In terms of media coverage and public attention, the eclipse also eclipsed the anniversary of the IAU vote.

One event involved embracing the public while the other centered on excluding them. We can only hope that renewed public engagement with astronomy continues to eclipse a bad decision by 424 non-experts 11 years ago.

Wednesday, August 16, 2017

The Great American Eclipse, August 21, 2017

This blog is mostly but not exclusively devoted to the issues of Pluto, dwarf planets, and planet definition. However, no planet or celestial body exists in isolation, and on various occasions, I have chosen to discuss other issues relating to planetary science and astronomy.

By now, most people are probably aware of the fact that a total solar eclipse will traverse the continental US on Monday, August 21. Locations outside the 70-mile path of totality, which crosses the country from northwest to southeast, as well as Canada, Central America, and the top of South America, will be treated to a partial solar eclipse.

Monday’s spectacle is a momentous occasion, a rare opportunity that should not be missed. While those who get to see the Sun completely covered by the Moon will hit the jackpot, the many more who will get to see a partial eclipse should not pass up the chance to do so—safely, of course, with eclipse glasses or indirectly using the pinhole projection method.

For anyone either clouded out or in other parts of the world, there will be numerous live online broadcasts in real time showing the stunning spectacle accompanied by educational commentary.

Unfortunately, some schools, both in and beyond the path of totality, are choosing to either do nothing for the eclipse or worse, keep students in rooms with drawn shades or no windows at all to prevent them from seeing it. Some are not even showing their students the online broadcasts.

These decisions rob children of a rare opportunity to see an unusual spectacle that can be watched safely. They reflect the way educational systems too often get things wrong, focusing on teaching to standardized tests rather than giving students an authentic learning experience.

In New Jersey, where I live, most schools don’t start until September, so this is not an issue. But in any state where schools are open, and bureaucrats make this indefensible choice, parents should either urge a policy change or keep their children home and watch the eclipse with them—even if that means watching online.

That’s right—Plutogirl is telling parents, even those not in the path of totality, in districts choosing to ignore the eclipse, to keep their kids home on August 21 and give them a better, firsthand educational experience than they would have received that day in school.

Such opportunities do not come around frequently. The US mainland has not seen a total solar eclipse since 1979. I would have loved to see one as a child, but there just weren’t any good ones during that time.

For people of all ages, this is a chance to take a break from disturbing national and world events and instead focus on the beauty of nature and a firsthand display of the motions of the Sun, Moon, and Earth. Seeing the results of these motions firsthand transforms our understanding of the solar system from abstract to experiential.

While I have personally seen several lunar eclipses, both total and partial, the only solar eclipse I’ve ever viewed personally was a very partial one in which, through telescopes made specifically for solar observing, one could see the Sun appear to have a small bite taken out of it.

I’ve known about this year’s total solar eclipse for at least ten years and probably longer. This one did not require traveling halfway around the world or to extreme climates. A decade ago, the first websites about this eclipse first went live online, emphasizing the goal of getting all Americans into the path of totality. I knew I wanted to go, and now it is actually happening.

Unfortunately, there are unscrupulous vendors who are selling counterfeit eclipse glasses that cannot be used to safely view the Sun. The American Astronomical Society has a list of reputable vendors of glasses and filters, which is posted at

The website EarthSky has information on watching the eclipse safely, which everyone should read, at

Watch online through any of the live video streams listed at

The Toshiba Vision screen in New York's Times Square will broadcast the program live in its entirety to give the public a big-screen view of the eclipse. Viewers in Times Square can listen to NASA coverage while observing it on the big screen by downloading the NASA app or going to

SLOOH, a remote observatory with live feeds from telescopes around the world, will also broadcast the eclipse free online at

Catch NASA’s live coverage using any of the following:

· NASA App for iOS --
· NASA App for Android --
· NASA App for Amazon Fire and Fire TV --
· The NASA App also is available to Apple TV users.

A list of additional smartphone eclipse apps can be found at

Happy and Safe Viewing!

Monday, March 27, 2017

The IAU--and Brown--Get It Wrong, Again

The Pluto/planet definition debate just took a turn toward the tenor of the 2016 US presidential election, with the most outrageous remarks coming from scientists.

It seems IAU Secretary General Piero Benvenuti and the scientist who co-discovered a planet but wants people to believe he “killed” one—Mike Brown—are tired of the debate and just want it to go away—or so they say.

Incredibly, Benvenuti thinks the debate has lasted this long solely due to Alan Stern! In a Canadian CBC News article dated March 24, 2017, he makes the following statement when asked why the debate has gone on for a decade after the 2006 IAU vote:

"Because of Alan Stern. Because of the Horizons team … Why am I not getting French schoolboys or Italian schoolboys or Iranian schoolboys writing to me about Pluto?"

There are so many things wrong with this statement that it’s hard to know where to begin addressing them!

Let’s start with the fact that the IAU describes its mission as “safeguarding the science of astronomy.”

Alan Stern spent 25 years tenaciously advocating an unmanned mission to Pluto. Because of his persistent dedication and effort, 7.5 billion people on Earth now have close up, high-resolution photos of Pluto. Because of the mission he fought for and put both brains and heart into for two-and-a-half decades, humanity has in-depth knowledge of the Pluto system, including its geology, its weather, its history, etc.

If not for the efforts of Alan Stern—along with those of the New Horizons team members—we would have nothing more than blurry pixelated images of this fascinating world.

One would think the head of an organization that bills itself as “safeguarding the science of astronomy” would give its highest commendations to a scientist who revealed a whole world and its system of satellites to the people of this planet.

Yet all Benvenuti can do is scapegoat and condemn Alan Stern—proof yet again that the IAU is more interested in safeguarding its self-appointed “authority” than the science of astronomy.

Galileo experienced a very similar reaction from the institution that saw itself as the “authority” of his day regarding astronomy.

Unfortunately for the IAU, the organization has no power to put Alan Stern under house arrest. Science by authority went out as of 1610.

Benvenuti does not even get the name of the Pluto mission right, erroneously referring to it as “Horizons” rather than New Horizons.

He claims French, Italian, and Iranian school boys—notice he did not even mention girls—are not sending him letters about Pluto. How do we even know this is true other than the fact that he says so? It’s quite easy to delete emails one does not want to read or send them to the spam filter. Benvenuti’s claim has no more to back it up than does Donald Trump’s claim that millions of illegal immigrants voted against him.

Even if schoolchildren of both genders aren’t writing to him, the reason is probably that they do not know who he is. People concerned about Pluto typically write to NASA, Neil de Grasse Tyson, and the American Museum of Natural History—the institutions or people they associate with either Pluto or astronomy in general. They are more likely to contact planetariums and observatories, especially those in their areas, than they are to write to the Secretary General of the IAU.

Benvenuti’s statement is a barely veiled claim that it is only Americans who care about Pluto’s status, and this is blatantly false. Support for Pluto’s planethood is not about American nationalism. It is about people looking at Pluto and seeing a planet.

If he thinks Alan Stern is the only reason the debate continues, he is sadly mistaken.

More than 300 planetary scientists signed the 2006 petition rejecting the IAU resolution. Numerous scientists have spoken and written against it over and over again for more than 10 years. And they have been joined by a large cohort of amateur astronomers, educators, writers, and members of the public around the world who continue to express their active opposition to the definition that states a dwarf planet is not a planet.

Even scientists not as vocal, such as Dr. Barrie Jones, author of Pluto: Sentinel of the Outer Solar System state they have no problem with the term “dwarf planet” but add that they reject the notion that dwarf planets are not planets at all. Many deliberately use the terms interchangeably as a quiet means of support for dwarf planets being a subclass of planets.

Here are just a few of the planetary scientists and science writers other than Stern who publicly and actively reject the IAU planet definition:

Kirby Runyon
Mark Sykes
Stephen Maran
David Grinspoon
Cathy Olkin
David Weintraub
Alan Boyle
Gerard Van Belle
Ken Croswell
Philip Metzger
Hal Weaver
David Rabinowitz
William McKinnon
David Aguilar
Fran Bagenal
Al Witzgall
Mark Showalter
Mike Buckley
Jim Bell
Carolyn Collins Petersen
Kevin Schindler
Tod Lauer
Will Grundy
Michael Summers
Kelsi Singer
Rob Gerardi
David Eicher
George Musser, Jr.
Ken Kremer
Mike Luciuk
Jason Schilling Kendall
Steve Russo
Jesús Martínez-Frías
Dennis Chamberland
Orkan Umurhan

This is just a short list, and I’m sure I will be adding more scientists and science writers to it.

There is also a huge movement online, sometimes humorously referred to as the “Pluto Resistance,” composed of thousands of people who have joined groups on Facebook and other social media opposing the IAU decision. Most also advocate planet status for the other dwarf planets, Ceres, Haumea, Makemake, and Eris. The largest such group is the Society of Unapologetic Pluto Huggers on Facebook.

Additionally, there are numerous websites such as,,, and many more, including this blog. These have stayed active for more than 10 years! Leading the “Pluto Resistance” for amateur astronomers and members of the public are Mike Wrathell, Raj Pillai, Bruce Reed, Carl Bergmanson, Michael and Nomi Burstein, P. Edward Murray, Janet Ivey-Duensing of Janet’s Planet, Steve Colyer, Andrew Brown, J. Richard Jacobs, Siobhan and Kevin Elias, Al Tombaugh, Annette Tombaugh-Sitze, Steven Raine, George Lewycky, Mark Andrew Holmes, Twila Gore Peck, Lawrence Klaes, Anthony Hallowell, Doug Turnbull, Scott Hedrick, Yael Dragwyla, Richard Hendricks, Gene Mikulka, John Bowman, Sr., and many more!

When Mike Brown says, “It's the same small group of people loudly complaining over and over the past decade” and claims the number of scientists who reject the IAU definition are “a vocal minority,” he is dead wrong.

His claim is the typical strategy of someone trying to discredit a movement by denying its popularity and attributing the position he opposes to only the outspoken people in the forefront. Like a typical politician, he simply repeats the same claim over and over again, with no proof whatsoever of its veracity.

Incredibly, Brown goes on to describe some of the pro-Pluto arguments as “insane!”

Of course, he does not say which arguments he deems insane. That would require him to give voice to those arguments and actually refute them. Ironically, he accuses the pro-Pluto side of being motivated by nostalgia and emotion when his tone makes it clear that his comments are driven by the emotion of frustration—frustration that he cannot get the world to accept his view of the solar system, even after more than a decade.

He, too, demonstrates ignorance regarding the New Horizons mission, stating, "If they can't make the case that the object that they sent their billion-dollar spacecraft to is interesting without having to co-opt the word planet, then they should have their spacecraft taken away from them. I mean, that's insane."

New Horizons’ total cost was $700 million, not billions of dollars.

Notably, JPL, where Brown is based, competed with APL in Maryland for a Pluto mission proposal in 2001. APL ultimately won the contest, which may be the source for the statement about taking the spacecraft away from the New Horizons team.

One thing supporters of the IAU definition have jumped on is the geophysical proposal’s inclusion of spherical moons as planets. The media has not helped, depicting the idea as far-fetched when that is hardly the case. Some of the top contenders for hosting microbial life in our solar system are spherical moons. These could someday be destinations for solar system colonization.

Even the evasive “Earth 2.0” could end up being the large moon of an even bigger exoplanet.

Spherical moons have been referred to as secondary or satellite planets for centuries. Their scientific classification as planets does not mean people cannot continue to refer to them as “moons.” It simply distinguishes those moons large enough to be rounded by their own gravity from the smaller, irregularly-shaped ones.

Brown exploits the issue of moons when, presuming to speak for everyone, he audaciously claims, “Nobody wants the Moon to be a planet” and laughs about it.

Since Brown personally and financially benefits from the Pluto debate by selling books and giving paid talks, one could question whether he really wants it to “go away.”

But contrary to his claim, Pluto is not just “one of many thousands of objects in the outer solar system.” It is one of a class of planets most numerous in our solar system and very different from those thousands of tiny KBOs.

Ironically, the world will get to know small planets, KBOs, and the outer solar system thanks to New Horizons’ extended mission.

If Benvenuti really wants the debate to “go away,” he should ask the IAU to rescind or suspend the 2006 resolution based on new data about Ceres and Pluto as well as the ever increasing number of strange exoplanets being discovered. Such a statement could simply acknowledge that it is far too early in our exploration of planets to come up with any specific definition, especially one so polarizing and exclusionary.

The IAU seems to want people to blindly follow its edicts. Maybe they need a reminder of Albert Einstein’s admonition, “Unthinking respect for authority is the greatest enemy of truth.”

We are not going away. The Pluto Resistance continues…

Sunday, March 26, 2017

Tuesday, March 14, 2017

Pluto: Science has not spoken, and no one has to move on

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

Both articles—the 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 the case.

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:

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.

Thursday, March 9, 2017

Hope for Pluto—Should We Re-Redefine Planets?

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.

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 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): and