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What is a Planet? [Sep. 18th, 2014|12:28 am]

This Pluto debate at Harvard will be broadcast live online! Don't miss it!
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Pluto Picture of the Day and Countdown to Pluto [Sep. 3rd, 2014|04:58 pm]
The countdown to the New Horizons flyby has begun! See a new Pluto Picture of the Day every day, plus a countdown clock to next year's flyby, here:
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ALS Ice Bucket Challenge, Pluto Version [Aug. 25th, 2014|11:12 pm]
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Pluto Eve: Anniversaries and Milestones [Aug. 24th, 2014|12:19 am]
As noted many times in this blog, August 24 is the day that will live in infamy, the day in 2006 when four percent of the IAU violated their group’s own bylaws and voted for the controversial resolution that demoted Pluto and established a very flawed definition of the term planet.

But this year, also known as Pluto Eve, this date is much more than the anniversary of a poor decision that never really stuck.

This year, August 24 and the next day, August 25, are a celebration of milestones past, present, and future.

Twenty-five years ago, on August 25, 1989, the Voyager 2 spacecraft made its closest approach to Neptune, sending back beautiful images of the blue planet and its largest moon, Triton, that excited people around the world.

Distant Neptune had never before been seen up close, and little was known about it before the completion of the Voyagers’ Grand Tour of the solar system’s gas giants.

I remember being entranced by Neptune’s vivid blue color, so much so that I actually felt compelled to paint the planet in watercolors surrounded by the black background of space. I collected every Neptune image I could find from the flyby and still have most of them.

The Neptune flyby revealed more than just the blue planet and its surface features. Images of Triton showed it to have a thin atmosphere, some volcanic activity, some craters, and a crust of frozen nitrogen on top of an icy mantle likely covering a core of metal and rock.

With a diameter of 1,680 miles, Triton is bigger than Pluto, which has an equatorial diameter of 1,430 miles. Because it orbits Neptune in the direction opposite the giant planet’s rotation, Triton is believed to have once been a planet that orbited the Sun on its own only to be subsequently captured by Neptune, becoming its largest moon.

Like Pluto, Triton likely originated in the Kuiper Belt, which is why it is viewed by many scientists as an analogue for Pluto. At the Pluto Science Conference last year, images of Triton were discussed and presented because these two objects are believed to be very similar.

Both are geologically active, slightly smaller than Earth's moon, possess thin, nitrogen-dominated atmospheres and have various ices (of carbon monoxide, carbon dioxide, methane and nitrogen) on their surfaces, as noted by Dr. Paul Schenk of the Lunar and Planetary Institute in Houston, Texas.

The excitement over the first ever images of Pluto New Horizons will deliver in less than one year in many ways parallels the reaction many had to the first views of Neptune and Triton in 1989.

In an unusual coincidence, August 25, 2014 is an important milestone linking the Voyager 2 and New Horizons missions. On this day, New Horizons will cross the orbit of Neptune, putting the spacecraft in what team members call “Pluto space.”

This milestone is the final planetary orbit crossing for the vehicle launched on January 19, 2006 and crossed the orbit of Uranus on March 18, 2011.

To commemorate both the Neptune flyby anniversary and New Horizons’ latest milestone, Schenk used footage from the 1989 Triton flyby and restored the photos to create a new, higher resolution map of Triton that has been made into a video.

That video can be viewed at . Schenk discusses this work on his blog at .

This new, enhanced view of Triton is an enticing preview of what we may find at Pluto in less than one year.

To commemorate these occasions, NASA TV will air a program on Monday, August 25 from 1-3 PM EDT live from Washington, D.C. at .

The schedule is as follows:

• The 1-2 p.m. event will feature a panel discussion with:
Jim Green, director, NASA’s Planetary Division, Science Mission Directorate, NASA Headquarters, Washington
Ed Stone, Voyager project scientist, California Institute of Technology, Pasadena
Alan Stern, New Horizons principal investigator, Southwest Research Institute, Boulder, Colorado

• The 2-3 p.m. event will include several New Horizons science team members giving personal accounts of their work during the Voyager Neptune encounter and their new assignments on the Pluto mission. Panel participants include:

Moderator: David Grinspoon, Planetary Science Institute, Tucson, Arizona
Fran Bagenal, University of Colorado, Boulder
Bonnie Buratti, NASA Jet Propulsion Laboratory, Pasadena, California
Jeffrey Moore, NASA Ames Research Center, Moffett Field, California
John Spencer, Southwest Research Institute, Boulder, Colorado

Media can ask questions from participating NASA locations, or by telephone. To participate by phone, reporters must contact Steve Cole at 202-358-0918 or and provide their media affiliation by noon Monday.

I will be phoning in and hopefully get to ask at least one question, then following up with an article about the event at The Spaceflight Insider, at .

Media and the public can also ask questions during the event via social media using the hashtag #askNASA.

What has come as a genuine surprise is the sheer amount of attention Pluto and the New Horizons mission have been getting an entire year prior to the flyby. I did not expect this much attention and activity centered on Pluto before 2015 began. The fact that there has been this much excitement starting more than a year in advance is more than encouraging.

And it shows just how wrong those who dismiss the ongoing debate over Pluto’s status are.

As has been pointed out many times, New Horizons launched seven months before the 2006 IAU General Assembly. Given the knowledge that a probe was already on its way to Pluto, why wouldn’t the organization wait until the images and data come in before making a decision? In science, the conclusion is drawn as a result of the experiment, not before the experiment takes place.

This mistake will continue to haunt the IAU and its decision no matter how much the group’s leadership digs in its heels and refuses to reopen the discussion. The images and data produced by New Horizons, which will continue to come in through the end of 2016, will by far eclipse a decade-old decision that becomes more and more irrelevant with every new discovery.

This is the last August 24 when we will not have close-up images of Pluto. Next August 24, we will have the most clear idea yet of just how alive a planet one astronomer prematurely wrote off as dead is.
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NASA TV to Air Events That Highlight Pluto-Bound Spacecraft | NASA [Aug. 22nd, 2014|11:08 pm]
NASA TV to Air Events That Highlight Pluto-Bound Spacecraft | NASA
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Astronomy and Science Educator Jason Kendall [Aug. 14th, 2014|01:21 am]
Astronomy and Science Educator Jason Kendall

Pluto, The Battle for a Planet
A special Homecoming event at William Paterson University
Saturday, September 20, 7:30 PM - 11:30 PM.
Science Hall East, WPU
Free and open to the general public
Stargazing hotline: 973-720-485
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New Horizons spies Pluto and Charon, July 2014 | The Planetary Society [Aug. 8th, 2014|12:26 am]
New Horizons spies Pluto and Charon, July 2014 | The Planetary Society
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Pluto's Place in the Solar System by Elizabeth Howell — Beacon [Aug. 4th, 2014|05:59 pm]
Pluto's Place in the Solar System by Elizabeth Howell — Beacon

Let's support this!
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Suppressing Debate??? [Jul. 31st, 2014|07:02 pm]
Are there some people with vested interests in keeping the flawed IAU planet definition intact who would go so far as to suppress any attempt at further open debate?

This question is not hypothetical. On July 29, 2014, Newsday posted an article by writer Delthia Ricks titled “Pluto Planet Controversy Rages on Among Scientists.” That article can be found here:

Because there were many issues raised in the article that needed to be addressed, I and several other Pluto advocates wrote comments in response to the article.

While my comment followed the site guidelines and did not involve inappropriate language or personal attacks or anything else that might disqualify a comment from being posted, it never saw the light of day.

Today, only two days later, the article notes “Comments are Closed.” At least one other comment was deleted, yet ironically, a spam comment with the typical “My aunt made money online, and so can you” remained posted.

The article and comments in response to it were discussed on the Facebook group “Society of Unapologetic Pluto Huggers.” In that discussion, I mentioned that my comment was never posted, but a spam comment was.

Several hours later, the spam comment is no longer there.

The article noted support from Astronomy magazine editor David Eicher for a debate on the topic of Pluto and planet definition, a challenge Stern recently issued to Tyson.

The writer then stated that neither Neil de Grasse Tyson nor Alan Stern could be reached for comment.

Something about this seems off. As busy as Stern is, he is known to be extremely reliable in following up with requests, especially by the media, to discuss Pluto.

Astronomers who did manage to get quoted in the article presented arguments one could accurately describe as less than stellar.

A Dr. Denton Ebel, who chairs the Earth and Planetary Sciences Department at the American Museum of Natural History in Manhattan, supposedly “cringes at the thought of ‘the Pluto discussion’ presents incorrect information four years out-of-date by stating that Eris is larger than Pluto. Presumably referring to Eris, he states, "There's an object in the Kuiper belt that is larger than Pluto, and it isn't a planet.”

In November 2010, a team of astronomers led by Dr. Bruno Sicardy obtained a more accurate measurement of Eris’s size and determined it is marginally smaller than Pluto though 27 percent more massive. More massive means more rocky and therefore more planet-like.

Why would an astronomer in such a prominent position at the American Museum of Natural History in New York “cringe” at the Pluto discussion? One would think astronomers would celebrate any public interest in astronomy, seeing it as a jumping off point to engage and interest the public.

The writer also quotes Dr. Fred Walter, a professor at the University of Stony Brook, who proceeds to attribute support for Pluto’s planet status to emotion, saying, “Clearly, it’s a touchy subject.”

Obviously a dynamicist, Walter goes on to say, "Pluto isn't gravitationally independent. It's gravitationally tied to Neptune."

There is nothing wrong with a dynamical view of the solar system. However, the author never mentions that the real debate is between the dynamical view, which requires objects to gravitationally dominate their orbits to be considered planets, and the geophysical view, which does not require this gravitational dominance and defines a planet as any non-self-luminous spheroidal body in orbit around a star, in orbit around another planet, or free floating in space.

Here, then, is either deliberate bias or a lack of awareness on the part of the writer. She presents the controversy as gravitational dominance versus emotion rather than quote a single astronomer explaining and advocating the geophysical planet definition. And that is a disservice to readers.

Walter goes on to say, "We haven't really fully demoted Pluto. The word 'planet' is still there," he said, referring to the term dwarf planet. "But if you were Pluto," he asked, "would you rather be the runt among planets, or the king of the dwarf planets?"

He seems unaware of the fact that the IAU definition specifically precludes dwarf planets from being considered planets. The “what would Pluto prefer” amounts to a straw man argument. The debate is not about what Pluto “prefers.” It is about what constitutes the best classification system, what definition best helps us understand the solar system and put objects in their proper contexts.

A definition that blurs the distinction between shapeless iceballs and rock (comets and asteroids) on the one hand, and a geographically differentiated, complex world similar to the terrestrial planets in all but size on the other hand constitutes a scientifically poor definition.

Walter’s presumption about “what Pluto prefers” is nothing more than a case of him projecting his own view onto Pluto.

Walter also notes that Pluto has “the most extreme orbit of any of the planets.” While that may be true in our solar system, he fails to mention that of the nearly 2,000 exoplanets now discovered, many giant planets, some bigger and more massive than Jupiter, have orbits far more eccentric than Pluto’s. Should those not be classed as planets?

Ebel is quoted with the old standby, "There are lots of objects out there and we are still finding new ones. But everything can't be a planet."

But everything in hydrostatic equilibrium, meaning rounded by its own gravity, and not a star, can and should be considered planets. Where is the science in arguing we cannot have too many planets?

In fact, every single astronomer the writer quotes presents the anti-Pluto view.

Amateur astronomer Ken Spencer, president of the Astronomical Society of Long Island, is quoted as saying, "In my heart, I know that it really can't be a planet anymore. I was really sad to see it demoted. But after reading why, it's hard to argue with those reasons."

Actually, it isn’t hard to argue with the IAU’s poor reasoning at all. It just seems the writer of this article found it too hard to locate and interview a single astronomer who can explain just why the IAU demotion is so flawed, using only his or her brain, no heart or feelings necessary.

The article ends with Walter citing anecdotal evidence that he believes supports his case, once more beating the drum of “it’s all based on emotion.”

He says, "It's only older people who think differently. This is a sociological issue, not a science issue because people don't want to give up what they learned in school."

This sounds a lot like Walter seeing exactly what he wants to see. Many astronomy educators and outreach people have experienced just the opposite, that children not even born when four percent of the IAU voted back in 2006 still strongly support designating Pluto and all dwarf planets as a subclass of planets.

Walter says, "I don't tell the students what Pluto is. I let them vote. And overwhelmingly they say Pluto is not a planet.”

I’m going to take a chance here and say that while he lets the students vote, he introduces the subject by sharing his view on it. Unfortunately, in many cases, students do not feel they can or should argue with their professors. The notion of “just give the professor what he/she wants to hear” to get a good grade is a genuine problem and likely serves to bias many students in favor of the position their instructors hold.

That part might be sociological, but the question of a dynamical versus a geophysical planet definition, as well as the need for a definition that includes exoplanets, most certainly is a scientific issue.

Assistant Professor of Earth and Atmospheric Sciences at the Georgia Institute of Technology Dr. Carol Paty is paraphrased as saying that even though New Horizons will present data about Pluto that scientists never before knew, she doubts Pluto will be reinstated.

How professional of her to draw a conclusion before the data is in. Maybe this is what she wants to happen--or not happen. She also fails to acknowledge that the IAU is not the only game in town. Another organization could very well form and come up with its own, better definition.

Interestingly, the last comment posted on the site, by an anonymous writer who simply identifies him/herself as “An Astronomer," reads “There is no debate. Astronomers say Pluto is not a planet by definition. A magazine editor and Facebook page creators have no standing to even suggest reclassification. The title of this article is incorrect and embarrassing. Pluto is not a planet. Case closed.”

So there we are. Once again, “Case Closed.” “No Debate.” “It’s Over.” “Astronomers Decided.” This is the same attitude we have heard from the IAU and supporters of its definition for eight years. It is the same mentality that led the IAU leadership to refuse to even consider reopening the debate at its General Assembly in 2009, when asked by a group of planetary scientists to do so.

Usually, decisions made once for all eternity are confined to religion, not science.

The bottom line, is there are those who have a vested interest in never reopening the debate. Those who want the IAU definition to stand and be the only one know its weaknesses will be exposed if the debate is reopened. They see themselves as the victors and so do not want any reconsideration, regardless of the science. Just shut down debate altogether. This is the type of mentality one expects from politicians, not scientists.

I am not personally upset that my comment was not published. There are many very articulate people who uphold the geophysical planet definition, whose comments would likely do a better job advocating it than mine. Yet not a single one other than David Eicher of Astronomy magazine, who called for the debate, was quoted. Not a single pro-Pluto or pro-geophysical planet definition was quoted, and the only pro-Pluto comments posted were very limited and general and did not address some of the weaknesses of the arguments made by the astronomers cited.

Plus, the closing of comments after only two days is highly unusual. Could some astronomers have possibly contacted Newsday, exerting pressure to close the comments section?

The reality is that the IAU and advocates of its definition haven’t “won.” The debate still goes on eight years later not because of emotion, but because their decision did not do the subject justice and continues to be undermined by new data we learn about worlds in this solar system and others.

My comments on the Newsday article constitute mostly what I said here, but I am reposting them for anyone interested. I have contacted the writer about these issues and will keep readers of this blog informed of any responses I get.

The Comment:

The issue hasn't gone away because people inherently understand that the IAU definition makes no sense. It also makes no sense for the IAU leadership to dig in their heels and continually refuse to reopen the discussion, as they have done so far. Here are several other points that also need to be considered:

The IAU definition says planets must orbit the Sun rather than "a star," meaning it automatically precludes exoplanets from being planets.

The IAU definition does not allow for rogue planets, which do not orbit any star and float freely in space. A planet cannot "clear its orbit" if it has no orbit to clear!

Even if the IAU definition did allow for exoplanets, a large number of these, including worlds larger than Jupiter, would not meet its definition because they have orbits far more eccentric than Pluto's, are in 3:2 resonances with other planets in their systems, plow through belts of asteroids during their orbit, share their orbit with another planet, etc.

One of the original motives for demoting Pluto was a perceived need to keep the number of solar system planets small. That has no scientific basis whatsoever. We already know the universe has billions of planets. If our solar system has nine, 90, or 900, then that is what it has. We can distinguish the different types of planets through the use of multiple subcategories.

Ebel is incorrect when he says there is an object in the Kuiper Belt larger than Pluto. His data is nearly four years old. In November 2010, Eris, the object to which he refers, initially thought to be larger than Pluto, was found to be marginally smaller than Pluto when it occulted a star.

Opposition to Pluto's demotion is not based on emotions, and you do a disservice by attributing the position to feelings. Opposition to Pluto's demotion and support of its planet status is based on the scientifically sound geophysical planet definition, the one adhered to by Dr. Stern and many professional astronomers who view dwarf planets as a subclass of planets. According to the geophysical planet definition, a planet is any non-self-luminous spheroidal body orbiting a star, orbiting another planet, or free floating in space. If an object is large enough and massive enough to have attained hydrostatic equilibrium, meaning it is squeezed into a round shape by its own gravity, according to the geophysical planet definition, it is a planet.

Significantly, Stern is the person who first coined the term "dwarf planet," and he did so with the intention that it would refer to a third class of planets in addition to terrestrials and jovians, not to non-planets.

Regardless of which is bigger, both Pluto and Eris are well beyond the threshold for being in hydrostatic equilibrium, meaning according to the geophysical planet definition, both are planets.

In fact, it is the supporters of the IAU definition whose decision is based on emotion, specifically, the position that our solar system cannot have too many planets because kids will not be able to memorize their names. Our solar system has whatever number of planets it has, and memorization is not important for learning; what is important is an understanding of the different types of planets and their characteristics. We don't ask kids to memorize the names of all the mountains and rivers on Earth or of all Jupiter's 67 moons.

This debate remains ongoing because people ranging from children to professional astronomers understand that the IAU definition, adopted by only four percent of its members, most of whom are not planetary scientists, is a very poor one and was adopted in a flawed process that violated the IAU's own bylaws. Significantly, an equal number of professional astronomers signed a formal petition rejecting the IAU definition.

The media erred in reporting one position, the IAU view, as fact, when what it really is is one view in an ongoing debate. To adherents of the geophysical planet definition, Pluto never stopped being a planet, and our solar system does not have eight planets; it has a minimum of 14 and counting.

Walter is also incorrect about an "age divide." Scientists strongly on either side of this debate tend to see what they want to see from the public and students. I and many amateur and professional astronomers have done a lot of outreach over the last eight years and have found that people of all ages overwhelmingly support Pluto's status as a planet.

Notably, unlike the overwhelming majority of Kuiper Belt Objects, Pluto has most of the same features that larger planets have. It has geology and weather; is differentiated into core, mantle, and crust; and may even harbor a subsurface ocean. As Dr. Stern says, "And I can’t think of a single distinguishing characteristic that would set apart Pluto and other things that you’d call a planet, other than its size. So I like to say, a Chihuahua is still a dog."

For more on the case for Pluto, visit my Pluto Blog at
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The Pluto Debate [Jul. 30th, 2014|04:35 pm]
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