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Saturday, August 24, 2013

Can't Keep A Good Planet Down

Seven years ago today, in a harried, last-minute highly political act, four percent of the IAU decided Pluto should be stripped of its designation as a planet and should instead be classified as part of a new group of objects, the dwarf planets—which, they said, are not planets at all even though the word “planet” is part of the category name.

It’s hard to believe seven years have passed since that ignominious day. And while some astronomers determined to keep planet Pluto “dead” are likely to gloat about the “new solar system” and brag about how this definition will last for another 80 or so years, what is even more incredible is the way Pluto’s status has remained an active topic of debate over the better part of a decade, at a time when members of the public are decried for their short attention spans.

In just the last year, we have celebrated the 35th anniversary of the discovery of Charon, Pluto’s large moon/binary planet companion, with New Horizons taking its first image of Charon. With its entourage of five moons and counting (four if you count Pluto-Charon as a binary system), this little planet never fails to generate intense interest and long discussions, both online and offline.

Meanwhile, the IAU has managed to stir public ire twice in 2013 alone, first by rejecting the name Vulcan, which received the highest number of votes in a contest sponsored by the SETI Institute that asked the public to suggest names for Pluto’s fourth and fifth moons, and then by condemning the private company Uwingu for launching a fundraiser through which people were asked to submit names for the exoplanet Alpha Centauri Bb and for the larger effort of creating a “Baby Book” of exoplanet names.

Each of these incidents brought people’s attention back to the IAU’s worst debacle seven years ago and reinforced the image of an elitist group out of touch with the general public.

That is likely the reason that earlier this month, the IAU reversed itself on the naming of exoplanets.

This reversal appears to be part of a slow, but inexorable change on the organization’s part, a recognition that its mission to “safeguard the science of astronomy” requires a respectful relationship with the public rather than a dictatorship.

One year ago, at its Beijing General Assembly, the IAU finally approved electronic voting, which will enable members who cannot attend future General Assemblies to have a voice in important decisions by voting remotely.

That rule change is laid out here: .

“15.a. To enable the widest possible participation of Individual Members the Executive Committee may decide that voting on certain issues of a primarily scientific nature, as determined by the Executive Committee, shall be open for electronic voting for not more than 31 days counting from the close of the General Assembly at which the issue was raised.

15.b. The Executive Committee shall give Members not less than 3 months notice before the opening of the General Assembly of the intention to open certain issues to electronic voting after the General Assembly.”

At this site, , Nancy Atkinson describes the change in policy regarding the assigning of popular names to exoplanets and on allowing members of the public to take part in that process.

The new IAU position, published online only ten days ago, states: “It is therefore in line with a long-established global tradition and experience that the IAU fully supports the involvement of the general public, whether directly or through an independent organized vote, in the naming of planetary satellites, newly discovered planets and their host stars.”

The announcement outlined a set of rules for public submission of exoplanet names that can be found in Atkinson’s article above.

Dr. Alan Stern remains skeptical of the decision, noting it still preserves IAU authority by requiring members of the public to submit exoplanet names to the organization. “Why should the IAU be a traffic cop?” he legitimately asks.

Stern points out that this statement contradicts an earlier one made by the IAU in April. In that statement, the IAU said: “These [naming] campaigns have no bearing on the official naming process — they will not lead to an officially-recognized exoplanet name, despite the price paid or the number of votes accrued.”

Readers of this blog may at this point see where I am going.

As the popular 1960s song goes, “The Times, They Are A’Changing.” The days of authoritarian decrees by a tiny unelected group are numbered. People interested in and involved in astronomy want to have a say in astronomical matters. They want to have input into names and yes, designations, of new discoveries. Chances are, the IAU leadership is making these concessions not because they want to, but because they see the way the wind is blowing and desperately don’t want their organization to become irrelevant and obsolete.

I may be overly optimistic here, but if the public and media can get the IAU to change its stance on naming exoplanets, maybe, just maybe, we can get them to reconsider the issues of planet definition and the status of all dwarf planets, including Pluto.

And if such efforts go unanswered, the IAU is not the only game in town. Astronomy today needs inclusive workshops and consensus building, not a “traffic cop.” As the late Patrick Moore often urged, the field needs an organization that includes amateur astronomers and both respects and welcomes their input.

Back in January, when I first learned of the new policy allowing electronic voting, I wrote to IAU Secretary General Dr. Thierry Montmerle asking for the IAU to reopen discussion on 2006 Resolutions 5a and 5b at its 2015 General Assembly, so that the 96 percent of members who were not in that room in Prague could have a say in the matter.

While noting that a group of IAU members would have to submit a draft resolution several months in advance of the 2015 General Assembly and specifically request it be subjected to electronic voting, as per IAU rules here , Montmerle went on to say,

“To be honest, I doubt that any group of astronomers will do what you suggest. There is no indication among the professional community of any will to reconsider the Prague Resolution, and now two GAs have passed without reaction. So personally I would see absolutely no justification (especially taking into account the progress made since then) in bringing up the same issue once again nine years later.”

It is disturbing to hear a high level IAU official dismiss reopening a relevant discussion three years in advance of the General Assembly. One gets the sense that the IAU leadership has made up its mind and does not want to be confused with the facts.

Then again, the events of 2013 illustrate that the IAU is capable of reversing its position if momentum in the astronomy community is clearly moving in a different direction.

Here are the points I noted in response to his message, in favor of a re-vote in 2015:

“I respectfully disagree with you regarding reason to bring up this issue nine years after the Prague decision. As I'm sure you understand, all understanding in science is subject to change based on our discovery of new information. At one time, astronomers thought all solar systems formed and are organized just like ours. Today, we know from exopanet discoveries that this is not the case. Similarly, several developments have occurred since 2006 or will occur by 2015 that could be regarded as compelling a reconsideration of the definition of planet.

1. The New Horizons flyby of Pluto and the Dawn flyby of Ceres will both take place in 2015, and the data these missions will provide will give scientists unprecedented understanding of the composition of small worlds that are large enough to be in hydrostatic equilibrium. These missions will show us two dwarf planets up close and personal, and their findings will likely trump all previous knowledge about such worlds. How could this new knowledge not compel a reconsideration of the concept of planet, including the question of whether dwarf planets should be classified as planets?

2. A huge number and variety of exoplanets have been discovered since 2006. Initially, the goal of creating a definition for the term planet was intended to include both planets in our solar system and in others. As Dr. Jocelyn Bell Burnell said at the 2006 GA, ‘You will notice that the heading of the resolution is definition of a planet in the solar system. We originally hoped to be able to define planet more widely, but we found it too difficult to manage appropriate wording on the timescale that we had. So today, we are talking only about objects in the solar system. We do know that there are other planets beyond our solar system. We are just not looking at them today.’

The IAU may not have had time to consider exoplanets in 2006, but the intention was never to not include exoplanets at some point in the future. Many giant exoplanets discovered today would not meet the criteria of ‘clearing their orbits.’ Only days ago, Formalhaut b was confirmed to have an extremely elliptical orbit that takes it through a disk of debris. Formalhaut b does not remove that debris when it crosses it nor does it capture the debris into its orbit. Therefore, Formalhaut b can be viewed as a world that does not ‘clear the neighborhood of its orbit.’

It is understandable that at first, a definition was created only for planets in our solar system. However, the Copernican principle reminds us that Earth and its solar system are not ‘special’ or at the center of anything. They are just one of many stellar systems with planets. Therefore, it behooves astronomers to standardize a planet definition that fits both our solar system and others rather than hold on to one that somehow gives a ‘unique’ or ‘privileged’ status to Earth's sun and planets.

3. Six years after the IAU vote, the planet definition adopted remains a matter of ongoing controversy and debate. Given the fact that only 424 IAU members voted on that definition, doesn't it make sense to revisit the issue now that electronic voting has been enabled? Many IAU members expressed dismay at having not had a voice in the 2006 debate because they were not present in Prague on the day of the vote. A group of professional astronomers, many of whom are IAU members, signed a formal petition rejecting the IAU definition and in 2009, asked the IAU GA to reopen the issue, only to be rebuffed. Why not include more voices and gain the type of strong consensus that will only strengthen a new planet definition? More voices, including more planetary scientists, can only enrich the discussion.

Nothing in science is set in stone or decreed ‘forever.’ I ask you to take into account the above factors as compelling arguments in favor of revisiting this subject with much more data and significantly more input, nine years after 2006.”

In response, Montmerle said he saw no purpose in continuing this discussion.

What Montmerle didn’t acknowledge in his email to me is that the lack of motivation among the professional astronomy community to reconsider the Prague resolution largely stems from the fact that many astronomers are simply ignoring it altogether. One could argue that that is a much easier route than spending time wrestling with an entrenched bureaucracy, allowing professional astronomers to devote precious time to research rather than politics and procedure.

Dr. Stern confirms this in his most recent report on the New Horizons mission, which can be found here: . He noted that during the Pluto Science Conference last month, many of the speakers, including some who do not view dwarf planets as planets, continually used the word “planet” in discussing both Pluto and Charon.

He writes, “Throughout the proceedings, scientists of all stripes, including some who don’t regard dwarf planets as planets, repeatedly referred to both Pluto and Charon (though never their small moons) as ‘planets.’ I wasn’t very surprised by this, since I hear it a lot at other conferences too, until one colleague asked me, ‘Why do you think [names withheld] referred to Pluto and Charon as planets when they didn’t sign the petition rejecting the IAU’s planet definition that excludes dwarf planets?’ I was surprised by her answer to her own question: ‘I think it’s because they subconsciously think of Pluto and Charon as planets, and they can't help but say it in when referring to them.’”

On the occasions when the 2006 IAU decision was mentioned at the conference, I couldn’t help but notice that it triggered amused laughter among many in the room.

With less than a year and a half to go until New Horizons begins transmitting its first close-up observations of Pluto in January 2015, Pluto is bound to be a hot topic of discussion in the near future.

That means two parallel discussions loom large on the public radar when it comes to astronomy. One is the role of the IAU in decision making while the other is New Horizons’ reconnaissance of Pluto. This is a good thing because ultimately the two topics are intertwined with one another.

So when a particular astronomer walks around saying that it takes a lot of work to keep Pluto “dead,” the reason for that should be obvious. Seven years after a decision the IAU, or at least four percent of it, desperately wanted to be the final word on the matter, the debate continues. Planet Pluto is very much alive and kicking. You just can’t keep a good planet down.

Thursday, August 22, 2013

Dr. David Grinspoon: It's Not About Pluto: Exoplanets Are Planets Too

Dr. David Grinspoon, a signatory to the 2006 petition rejecting the IAU demotion of Pluto, argues in this Sky and Telescope article dated August 16, 2013, that the major flaw with the IAU planet definition is that it completely excludes exoplanets.

Go to . On the left margin of the page, click on PDF Full Text to either open or download and save Grinspoon's article. He makes a lot of strong points, especially in light of the rapid rate of exoplanet discovery.

Wednesday, August 7, 2013

Pluto Conference Wrap-Up: Atmospheres, Magnetospheres, Predictions, and Resources--and Lollipops!

The last day of the Pluto Science Conference was only a half day, but speakers managed to get in a lot of discussion on the possible interaction of Pluto’s atmosphere with the solar wind, computer simulations of this interaction, X-ray emissions that might be seen from Pluto’s plasma (a state of matter containing charged particles, both positive and/or negative) environment, X-ray observations of Pluto by the Chandra Space Telescope (an X-ray telescope launched by NASA in 1999), predictions regarding Pluto’s wind structure, Pluto’s ultraviolet glow, and more, all connecting back to the New Horizons flyby in just two years.

Fran Bagenal, a huge Pluto supporter with whom I had fun comparing Pluto T-shirts, reported that Pluto interacts with the solar wind like a comet does, given its large atmospheric escape rate. The solar wind is a stream of charged particles released from the Sun’s upper atmosphere that varies in temperature, density, and speed with time and distance. Voyager 2 actually measured solar wind conditions at 30 AU, roughly Pluto’s distance from the Sun, even though it did not fly past Pluto, and found large variations in it.

Pluto has an extended, puffed up atmosphere, speaker Peter Delamere noted. This atmosphere presents an obstacle to the flow of the solar wind. New Horizons’ SWAP (Solar Wind at Pluto) instrument will look into the solar wind as it comes toward Pluto. Interestingly, the solar wind is currently a lot weaker than it was when Voyager 2 measured it.

On the day of its closest approach, SWAP will begin seeing ions from Pluto. As New Horizons departs, the instrument will likely get a good view of the long tail of ions coming from the planet.

Interstellar ions may also play a role in influencing just how the solar wind interacts with Pluto.

John Cooper questioned why some Kuiper Belt Objects appear red while others appear bright and still others dark. The cold classical KBOs are usually red. Objects created in cryogenic (very low temperature) material tend to be very bright.

Computer models have been utilized to study whether Pluto’s interaction with the solar wind is similar to that of a comet, as Bagenal stated, or whether that interaction is more like that between the solar wind and Venus. The solar wind can undergo many types of interactions with other objects. Four instruments on New Horizons—PEPPSI, REX, ALICE, and SWAP will provide data that could help answer this question.

X-ray observations will also assist in revealing the nature of the interactions between Pluto and the solar wind. This is because X-rays are very effective atmospheric probes and can tell us a lot about the escape rate of Pluto’s atmosphere. Such measurements have successfully been made of the interaction between comets and the solar wind. We can expect to see X-ray emissions from Pluto. During the New Horizons flyby, astronomers will seek observing time on the Chandra telescope, which can encompass Pluto and Charon with one pixel! This will enable very useful comparisons between New Horizons’ up close observations and ground-based observations from Earth.

With only two years until the flyby, excitement is building, and predictions abound. Angela Zalucha presented a computer model she created based on a Global Climate Model (GCM) used to study Earth’s climate. Her “Pluto GCM” assumes the planet has a dynamical core. The REX instrument on New Horizons will send radio waves through Pluto’s atmosphere while ALICE will measure the Sun’s light at Pluto as well as light from a background star shining through Pluto’s atmosphere. She emphasized that Triton is a very good analogue for Pluto.

Researcher Melanie Vangvichith also made use of a computer model, with the goal of creating a complete simulated 3D GCM of Pluto’s atmosphere for the years 1988-2016. Special focus was given to results for the years 2007, 2010, and 2015. Her model shows no troposphere (lowest atmospheric layer), unlike Triton; this is attributed to the abundance of methane on Pluto, which warms its atmosphere. Weather occurs when particles sublimate on the planet’s summer hemisphere and are then transported by wind to its winter hemisphere, where they subsequently condense.

While Vangvichith’s model produces results in agreement with Earth-based observations for this short period of time, it is uncertain whether it can produce the same accuracy when addressing changes over hundreds of years. This is largely due to difficulty in initializing Pluto’s surface and subsurface temperatures over such long periods, especially given its elliptical orbit.

A GCM model also based on Earth climate models created by Anthony Toigo produced its best results when its simulations of Pluto’s current climate assumed the existence of a relatively thick atmosphere. He noted that future studies of Pluto’s climate should focus on tides, general circulation, and surface winds.

To understand the evolution of a planet’s atmosphere, one needs to track the processes in that atmosphere. Nitrogen is the primary gas in the atmospheres of Pluto, Triton, Titan, and various large Kuiper Belt Objects. The ALICE instrument on New Horizons will analyze the composition and structure of Pluto’s atmosphere. It will also show the structure of Pluto’s darker regions against the interplanetary background.

The Cassini mission to Saturn observed ultraviolet airglow on Titan using a model known as AURIC, or Atmospheric Ultraviolet Radiance Integrated Code; New Horizons will use this model to measure ultraviolet airglow on Pluto. ALICE will make this possible by collecting atmospheric data in ultraviolet wavelengths. Interestingly, the AURIC model was initially created for Earth, then modified for Mars, Titan, and now Pluto.

ALICE’s observations are expected to show emissions of argon and nitrogen. Focusing on a profile of the planet’s limb (the outer edge of the planet’s disk) will reveal where the emissions are taking place.

New Horizons will encounter Pluto at a distance of 32.91 AU from the Sun (that is 32 times the Earth-Sun distance).

Stern closed the conference by reminding those present that this meeting was a follow up to a conference held 20 years ago at Lowell Observatory. That conference focused on turning the idea of a robotic mission to Pluto into a reality. Quite a few attendees at this year’s conference had attended that one, and to emphasize this, a picture of the 1993 group was displayed onscreen.

Papers presented at this conference will be published in a special edition of the journal Icarus.

The Pluto Science Conference featured more than just lectures. Two poster sessions were held, one on Tuesday and the other on Thursday, where attendees had the opportunity to view 30 posters and discuss them with the scientists who put them together. On Wednesday during lunch, a special “Triton Half Time Show” was presented, illustrating Voyager 2’s 1989 findings at Triton, which is believed to be a captured Kuiper Belt planet similar in composition to Pluto.

Looking ahead, Stern announced his goal of holding another conference in the summer of 2017 to digest and make sense of the findings of New Horizons, which will take approximately a year to be downlinked. The 2017 conference will lead to the compilation of a Pluto system book.
Abstracts of talks at this year’s conference are posted on . More detailed discussions of each speaker’s presentation can be found at Kimberly Ennico’s blog at . A summary of the conference and how it exceeded organizers’ expectations can be found here:

Only time will tell how accurate the predictions at this conference are in matching what is actually going on. It is worth remembering that prior to the discovery of planets orbiting stars other than the Sun, astronomers generally assumed other solar systems would look like ours. That turned out to be incorrect, to the point of sending scientists back to the drawing board in determining how planetary systems form. Whether models and predictions for Pluto are accurate or way off base will not be known until we actually see the planet and its moons up close.

Finally, to reward readers who hung in there and stayed with me to the end of these conference discussions, here is something on the lighter—and sweeter—side. I always urge supporters of Pluto’s planet status to vote with our dollars. Thanks to Kate McKinnon, wife of astronomer Bill McKinnon, who took part in the conference, I learned that one can buy solar system lollipops that DO include Pluto! Kate highlights these lollipops in a blog post titled, “Take That, Mike Brown!” That post can be found here:

To purchase these lollipops, visit the Colossal Shop, which is selling them as Solar System Lollipops, at , for $22 a set. Choose from a variety of flavors, including cherry, guava, marshmallow, strawberry, blackberry, and cotton candy.