Mike Brown's Planets

The Station Fire started near JPL on Thursday and went crazy yesterday, expanding to 20,000 then 35,000 and now who-know-how-many acres. Remarkably few structures have been lost.There is a good chance, though, that the little cabin that I lived in when I first arrived at Caltech is now ash (it's NOT! I just got word from an old neighbor that the canyon was saved. so hard to imagine looking at all of the destruction in the region). I might be wrong; in the major fires 15 years ago Millard Canyon was saved when fire skipped over the top of it. But from everything I can see things don't look good. The firefighters started protecting structures in the real city, not crazy cabins up in the woods. The cabin was at least 100 years old and had survived floods and fires that had slowly gotten rid of the cabins throughout the rest of the San Gabriels mountains.

It was a wonderful if somewhat eccentric place to live. I write about it in my forthcoming book (sadly, books take way too long, even after you finish writing them, so forthcoming means perhaps a year), and I wanted to give a little excerpt here, in memory of the little cabin that I fear met its doom yesterday or last night.

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When I first started looking for planets, I lived in a little cabin in the mountains above Pasadena. Though I cannot prove it, I am willing to bet that I was the only professor at Caltech at the time who lacked indoor plumbing and, instead, used an outhouse on a daily (and nightly) basis. I worked long hours, and it was almost always dark, often past midnight, when I made my way back into the mountains to go home for the night. To get to my cabin, I had to drive up the windy mountain road in to the forest, past the National Forest parking lot, down to the end of a dirt road, and finally walk along the side of a seasonal creek along a poorly maintained trail. For some time after I first moved in I tried to remember to bring a flashlight with me to light my way, but more often than not I forgot. Eventually I had no choice but to give up on flashlights entirely and, instead, navigate the trail by whatever light was available, or, sometimes, by no light whatsoever.

The time it took to get from the top of the trail to the bottom, where my cabin waited, depended almost entirely on the phase of the moon. When the moon was full it was almost like walking in the daylight, and I practically skipped down the trail. The darker quarter moon slowed me a bit, but my mind seemed to be able to continuously reconstruct its surroundings from the few glints and outlines that the weak moonlight showed. I could almost walk the trail with my eyes closed. I had memorized the positions of nearly all of the rocks that stuck up and of all of the trees and branches that hung down. I knew where to avoid the right side of the trail so as to not brush against the poison oak bush. I knew where to hug the left side of the trail so as to not fall off the twenty foot embankment that we knew as “refrigerator hill” (named after a legendary incident when some previous inhabitants of the same cabin bought a refrigerator and had hauled it most of the way down the trail before losing it over the embankment and into the creek at that very spot; I never lost a major appliance, but I took extra care – and used ropes – one time when I had to get a hot water heater down the hill to install at the cabin; it was rough going, but the new found ability to take hot showers was definitely worth it).

I had almost memorized the trail, but, every 28 days, I was reminded that, really, there is quite a big difference between memorization and almost-memorization.

Every 28 days the moon became new and entirely disappeared from the sky and I was almost lost. If by luck there were any clouds at all in the sky I could possibly get enough illumination from the reflected lights from Los Angeles, just a few miles away, to help me on my way, but on days with no moon and no clouds and only the stars and planets to light the way I would shuffle slowly down the trail, knowing that over here – somewhere – was a rock that stuck out – there! – and over here I had to reach out to feel a branch – here! It was a good thing that my skin does not react strongly to the touch of poison oak.

These days I live in a more normal suburban setting and drive my car right up to my house. I even have indoor plumbing. The moon has almost no direct effect on my day to day life, but, still, I consciously track its phases and its location in the sky and try to show my daughter every month when it comes around full. All of this, though, is just because I like the moon and find its motions and shapes fascinating. If I get busy, I can go for weeks without really noticing where it is in the sky. Back at the time I lived in the cabin, though, the moon mattered, and I couldn’t help but feel the monthly absences and the dark skies and my own slow shuffling down the trail.

Contrary to how it might sound, however, back then the moon was not my friend. The 2 ½ year-old daughter of one of my best friends – a girl who would, a few years later, be the flower girl as I got married, would say, when asked about that bright object nearly full in the night sky: “That’s the moon. The moon is Mike’s nemesis.” And, indeed, the moon was my nemesis, because I was looking for planets.

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The moon is nearing full tonight, but it's no longer my nemesis. That honor will now go to the Station Fire which I fear has taken away that place I loved so well.

Look! Titan has fog at the south pole! All of those bright sparkly reddish white patches are fog banks hanging out at the surface in Titan's late southern summer.

I first realized this a year ago, but it took me until now to finally have the time to be able to put all of the pieces together into a scientific paper that is convincing enough that I can now go up to any person in the street and say: Titan has fog at the south pole!

I will admit that the average person in the street is likely to say hmph. Or yawn. Or ask where Titan is. So let me tell you why finding fog at the south pole of Titan has been the scientific highlight of my summer.

Titan is the only place in the solar system other than the earth that appears to have large quantities of liquid sitting on the surface. At both the north and south poles we see large lakes of something dark. Oddly, though, we don’t actually know what that dark stuff is. At least some of it must certainly be ethane (that’s C2H6, for all of you who have forgotten your high school chemistry). Ethane slowly drips out of the sky on Titan, sort of like soot after a fire, only liquid soot in this case. Over geological time, big ponds of ethane could accumulate into the things that look like lakes on Titan. Odd as they sound, big lakes of liquid ethane are, at least to me, the least interesting possibility. They are the least interesting because ethane is a one way street. Once the liquid ethane is on the ground, it can’t evaporate and is there pretty much forever, unless it somehow sinks into the interior.

Why does all of that ethane drip out of the sky? Because sunlight breaks down methane (CH4) to form ethane much the same way it breaks down car exhaust fumes to form smog in big cities. There’s plenty of methane in the atmosphere, so the supply of ethane is near endless. The dripping will not end soon.

But the methane is where all of the potential action is. Methane is to Titan what water is to the earth. It’s a common component in the atmosphere and, at the temperature of Titan, it can exist in solid, liquid, or gas form. Like water on the earth, it forms clouds in the sky. Like water on the earth, it probably even forms rain. But what we don’t know is whether or not that rain makes it to the surface and pools into ponds or streams or lakes which then evaporate back into the atmosphere to start the cycle over again. In short, we don’t know if Titan has an active methane atmosphere-surface hydrological cycle analogous to the water atmosphere-surface hydrological cycle on the earth.

Until now.

Because there is fog.

Fog – or clouds – or dew – or condensation in general – can form whenever air reaches about 100% humidity. There are two ways to get there. The first is obvious: add water (on Earth) or methane (on Titan) to the surrounding air. The second is much more common: make the air colder so it can hold less water and all of that excess needs to condense. This process is what makes your ice cold glass of water get condensation on the outside; the air gets too cold to hold the water that is in it, and it condenses on the side of your glass.

Terrestrial fog commonly forms from this process. That fog that you often see at sunrise hugging the ground is caused by ground-level air cooling overnight and suddenly finding itself unable to hang on to all its water. As the sun rises and the air heats, the fog goes away. You can also get fog around here when warm wet air passes over cold ground; the air cools, the water condenses. And, of course, there is mountain fog that is causes by air being pushed up a mountain side, where it cools and – you get the pictures – can no longer hold on to all of its water so it condenses.

Interestingly, none of this works on Titan.

It’s really really hard to make Titan air colder fast. If you were to turn the sun totally off, Titan’s atmosphere would still take something like 100 years to cool down. And even the coldest parts of the surface are much too warm to ever cause fog to condense.

What about mountain fog? A Titanian mountain would have to be about ~15,000 feet high before the air would be cold enough to condense. But Titan’s crust, made mostly of ice, can’t support mountains more than about 3000 feet high.

We’re left with that first process: add humidty.

On Titan, as on earth, the only way to add humidity is to evaporate liquid. On Titan this means liquid methane.

Liquid methane! There it is!

Evaporating methane means it must have rained. Rain means streams and pools and erosion and geology. Fog means that Titan has a currently active methane hydrological cycle doing who knows what on Titan.

But there’s one more twist. Even evaporating liquid methane on Titan is not sufficient to make fog, because if you ever made ground-level air 100% humid the first thing it would do after turning into fog would be to rise up like a massive cumulous cloud. There’s only one way to make the fog stick around on the ground for any amount of time, and that is to both add humidty and cool the air just a little. And the way to cool the air just a little is to have it in contact with something cold: like a pool of evaporating liquid methane!

Our paper describing these results (written by me, Alex Smith and Clare Chen, two Caltech undergraduate students, and Mate Ádámkovics, a colleague at UC Berkeley) was recently submitted to the Astrophysical Journal Letters. The paper will shortly go out for peer review, which is an integral part of the scientific process where the paper is vetted by experts. Peer review, as implemented in the current world of over-stressed astronomers, has some serious flaws, though. One problem is that the peer review is performed by one person! Sometimes that one person is thoughtful and insightful and provides excellent insight and commentary. Sometimes that one person misses or misunderstands crucial points. It is rare, though, that any one person can be a broad enough expert in all of the topics in a scientific paper to provide adequate review of the whole thing. Plus people are busy.

What is the solution? I don’t know. There has been much talk recently about all of this, and even some interesting experiments done by scientific journals. I thought I would try an experiment of my own here. It goes like this: feel free to provide a review of my paper! I know this is not for everyone. Send it directly to me or comment here. I will take serious comments as seriously as those of the official reviewer and will incorporate changes into the final version of the paper before it is published.

What kinds of things would I look at closely if I were a reviewer of this paper? Probably things like: is the claim of discovery of something fog-like convincingly made? Is the fog-like feature really at the surface rather than simply a cloud? Is our argument of how fog must form convincing? Is it correct? These were, at least, the things I thought hardest about as I was writing the paper. Perhaps you will find more!

“Daddy! Daddy! You gave me those baby scissors!” she exclaimed, running over to her little table sitting in the middle of the kitchen and pulling out a pair of 4-inch miniature yet quite sharp scissors. She uses these most every day, though we almost lost those on a plane ride to Seattle this summer when we unthinking brought them in carry-on. I was both relieved and flabbergasted when the security inspector pulled them out, looked at them, and decided that they were OK to bring aboard.

“But Daddy, where is my mat?”

Mat? Mat? What mat? I thought and thought until I remember, with a little shock, that for my own amusement, I got Lilah a plastic “Nine Planets Placement” for Christmas last year that had nice photos and facts of all nine (ahem) planets. It had gotten shoved under a pile of other placemats in a drawer, but I dug down, pulled it out, and Lilah cheered.

“The planets!” Lilah exclaimed.

“Ugh” I thought.

With the third-year anniversary of the demotion of Pluto having just occurred, I’ve been thinking a lot about planets again (or perhaps I should just say “still”). But rather than worrying about planet classification anymore, which I think is on pretty solid ground these days, I’ve been wondering about the people who simply can’t give up on the concept that Pluto simply has to be a planet. Why are they so attached to the 18^th largest object in the solar system when they probably can’t even name all of the 17 larger things? (try this at home: can you without looking it up?)

Lilah’s placemat drove home a likely part of the problem. Most people have absolutely no idea what the solar system actually looks like. They see pictures of planets of placemats, on lunch boxes, on walls at school, but none get the scale of the solar system even remotely correct. Why? First: it’s boring. The solar system is mostly empty space. How much empty space? If you were to draw a top-down view of the solar system from the center out to the edge of the Kuiper belt, it would be 99.999999% (that’s 8 nines, if you’re counting) empty. And 99% of that non-empty fraction is taken by the sun. Making a placemat with that much empty space is pretty dull (though presumably you would save on printing costs). I would show you here what it would look like, except that you would need to view it on a monitor with 12,000 pixels across (about 10 times your typical laptop screen). The sun would occupy only one pixel in the center. You’d see nothing else. If you had grown up with a picture of the real solar system on your placemat, you would be forgiven for thinking the number of planets was precisely zero.

We need a better placemat. What’s the solution? There is no choice except to dispense with trying to depict both the distances between planets and the sizes of planets on the same scale. You can do a little better if you shove the sun almost out of the frame, keep the relative distances between the planets correct, and exaggerate the sizes of planets by a factor of about 8000.

(The Kuiper belt with Eris and Pluto and the rest is really there, way off on the right side. Try squinting.)

This solution still does not make for a great placemat. It’s still mostly empty space, and most things are too small to see well. If Jupiter is going to fit on your placemat at all (and let’s not even talk about the sun), Mercury is going to be so small that it will look like just a tiny dot (and, again, let’s not even talk about Pluto, which is half again smaller). If you had grown up with this placemat you would probably have a lot of respect for Jupiter and Saturn and wonder why everyone made such a big deal about the rest of them.

As a placemat maker, there is one other step you can take while still maintaining scientifically integrity. You can keep the planets in the right order, but give up on showing their true distances from each other. Shoving the planets together a bit more allows them all to be somewhat bigger. Now you can even make out Ceres, the largest asteroid. The band of tiny Kuiper belt objects begins to be visible.

“Alas!” cries the honorable maker of placemats. “How am I to put any artwork on tiny disks that size? What of the canyons on Mars? The scarps of Mercury? The mottled face of Pluto?”

There is a solution, of course. Forgo almost everything. You’ve already had to throw away the correct relative spacings between planets to make the placemat more interesting. Now also throw away the correct relative sizes! Make Jupiter and Saturn significantly smaller, make the tiny tiny terrestrial planets significantly bigger. Grossly exaggerate the size of puny Pluto. This is the perfect solution. This is Lilah’s placemat.

I find this solution perfectly awful.

My objection here is not the inclusion of Pluto as a planet (that’s just anachronistically cute, sort of like ‘here be dragons’ on an old map), my objection is that everything about the solar system is so wrong that of course people are going to be generally confused. How could astronomers possibly vote to get rid of Pluto when there it is, as big as Mercury, nearly as big as the earth itself?

Just how bad is it? If you take Jupiter to be the right size and scale everything from there, Mercury, Venus, Earth, and Mars should be 6,4,4, and 5 times smaller, respectively. The smallest ones, Mercury and Mars, are the most exaggerated.

The giant planets are a bit odd. Saturn is actually 80% too small, presumably because its rings take up too much space to be aesthetically pleasing. Uranus and Neptune are 1.2 and 1.5 times too big, respectively.

And Pluto? It remains the runt even in this solar system, where its size is exaggerated by a factor of 10.

If you grew up with a placemat like this, or a wall poster in your third grade classroom, or a lunch box you carried every day, I now understand why you feel Pluto still deserves to be a planet. It’s because you and I are talking about entirely different solar systems. Even I would agree to Pluto’s special place in the solar system of Lilah’s placemat. Sadly, that solar system and the real solar system have little in common.

I do have a better solution for the placemat makers out there. It keeps the relative sizes of planets correct and keeps their ordering correct, but, like all of the ones above, it has to dispense with the relative spacing between planets. The trick, though, is to pile the planets on top of each other, and to not even show all of the monster Jupiter. You can pack much more into the frame, like this.

There is room on this placemat to put real depictions of the planets. And you can even see many of the dwarf planets out in the Kuiper belt. If you look carefully, you can see the elliptical Haumea and you might even be able to identify a few other of your favorites.

Imagine a world in which this was the image that children – that adults! – had of the solar system. Would we even be having conversations about Pluto’s planethood? It seems pretty unlikely to me. Rather, we would talk of the great difference between giant planets and terrestrial planets, we would talk of the band of asteroids, and we would talk of the ever-increasing number of tiny icy objects out there on the very edge of the solar system. In short, we would talk science rather than definitions. But, occasionally, we would remember the old solar system of our youth and talk nostalgically to our children, and say “when I was your age, Pluto was still a planet” and then, when our child looked up quizzically, we would look down in the corner of the placemat, and try to point out the former planet amongst those many many objects and realize that we had absolutely no idea which tiny point it even was.

Look in your newspaper this Saturday, and you may see a paragraph about Saturn’s moon Titan and a giant storm that moved across the surface last May and what that means. With luck they’ll even print it with a tiny little picture of Titan to catch your eye. Your response, if you have one, will likely be “huh.” It’s OK. I’m not offended. It’s hard to distill the richness of a full scientific paper into a paragraph. And it’s even harder, still, to distill the richness of a decade of scientific inquiry into a short scientific paper. But if you’re curious about what that little paragraph means, and how it came to be in your newspaper, and what we’ve been doing for the past decade, read on. It’s a long story, but that’s somewhat of the point.

I became interested in Titan ten years ago, almost as a matter of convenience. It was an excellent solar system target for the then-new technique of Adaptive Optics, which attempts to undo some of the effects of the smearing of starlight caused by Earth’s atmosphere. Titan was a great target because it is just small enough to be completely smeared by the atmosphere, but big enough that, if you could unsmear it, you would still have a nice view. Just as importantly, no one had ever had a nice view of the surface of Titan before because the satellite it covered in a thick layer of smog which mostly doesn’t let light penetrate to the surface. When the Voyager spacecrafts flew by, they took pictures of Titan which look like a big orange billiard ball. I should have said, though, that visible light doesn’t penetrate to the surface. On the earth, red light penetrates smog better than blue light (hence the nice red sunsets on a smoggy day in Los Angeles). The same happens on Titan. Red penetrates better than blue, but infrared penetrates better still. In fact, if you go far enough into the infrared, you can take a picture of Titan and almost not notice any smog there at all. Conveniently, the new technique of Adaptive Optics works best in the infrared. Hence Titan became a natural target to try out the new techniques on. Antonin Bouchez, then a relatively new graduate student at Caltech, signed on to do this project as part of his Ph.D. thesis.

Our first goals were to obtain maps of the then-almost-totally-unknown surface of Titan. And what a strange looking surface it turned out to be! We speculated endlessly about what all of those dark and bright spots on the surface might be (for the most part it is fair to say that we – and everyone else – had no idea whatsoever until we got better images from Cassini a few years later). And then, in late 2001, we found a cloud sitting at the south pole of Titan.

A cloud!

It doesn’t sound like such a big deal, except that it had long been predicted that Titan was incapable of having clouds. Occasionally there was speculation that clouds of methane might be present, but that, if so, they would be tightly confined to the equator. And yet there it indisputably was: a cloud at the south pole.

Antonin and I were so astounded by this that we put Sarah Horst, then an undergraduate at Caltech, at work looking through a tiny 14-inch telescope on the roof of the astronomy building at Caltech. We had developed some special telescope filters which would – we hoped – be capable of penetrating the haze deck and seeing if Titan got a little brighter due to a cloud or two. We wouldn’t be able to tell anything else, but that would be enough to go back to the giant Keck telescope and say “Look now! There will be a cloud!”

It worked. Just a month after our first cloud detection Sarah saw something that looked just like what we expected a cloud to look like. We called people at the Keck telescope and begged them to snap a picture, and there it was. A much bigger splotch, still near the south pole.

I’m an astronomer, not a meteorologist. I had to spend six months learning about how clouds worked, trying to understand precisely why people thought they wouldn’t occur on Titan, and figuring out what was wrong. On a long summertime flight across the country where we continuously skirted afternoon thunderstorms, it all came together: no one had ever previously bothered to consider the effect of Titan’s surface heating. Like Arizona on a summer afternoon, Titan’s surface can heat up and eventually drive convective clouds over it. On Titan, though, it doesn’t happen in the afternoon. It happens in the summertime, when the south pole spends something like 10 years in continuous sunlight.

It was a compelling story, and, I think true. But, even better, it made some fairly clear predictions. The clouds were at the south pole when we discovered them only because it was very close to southern summer solstice. Titan (and Saturn) takes 30 years to go around the sun, so its seasons are quite long. But if you had the patience to watch, you should see the clouds move from the south pole to the north pole over the next 15 years before coming back 15 years later.

Antonin eventually got his Ph.D. and moved on to take a job working with the technical team continuing the development of Adaptive Optics at the Keck Observatory. It was the perfect place to be. Whenever there was a spare moment or two at the telescope, he would swing it over towards Titan and snap a picture. The clouds were nonstop. Sometimes there were just a few tiny specks, but occasionally there would be a huge outburst. It was a thrilling show to watch.

Emily Schaller entered graduate school at Caltech at just about that time, and she decided to do her thesis on watching and understanding these developing clouds on Titan. The first year was exciting, indeed. She saw a monster cloud system cover the south pole of Titan and remain for more than a month (disappearing just as one of the first close Cassini flybys went in to take pictures; Cassini saw a few wispy little clouds but missed almost all of the action). Henry Roe, a recently graduated Ph.D. from the University of California at Berkeley who had been using the Adaptive Optics on the Gemini telescope to study Titan, moved down to Caltech to work with us, and the odd discoveries about the clouds poured in. They appeared to finally move north from the pole; they appeared tied to one spot at 40 degrees south latitude for a while; they untied themselves; bright clouds in one spot seemed to foretell bright clouds in another. It was clear that we were amateurs here. We enlisted the help of Tapio Schneider, a professor of environmental engineering at Caltech and one of the world’s experts on atmospheric circulations, to help us make sense of what was going on. Things were finally falling into place.

In one final piece of exceedingly clever astronomy, Emily Schaller replaced our clunky nightly observations with a 14-inch Celestron, originally begun by Sarah Horst, with a sleek set of nightly observations from NASA’s Infrared Telescope Facility on top of Mauna Kea. The IRTF would take a quick spectrum of Titan every night possible, and Emily could quickly look at the rainbow of infrared light to tell precisely how many clouds were there. And when they looked good, she could tell Henry Roe, who would get the Gemini telescope to examine them.

And then the clouds stopped.

For years and years Emily would look at her data in the morning and walk across the hall to my office to mournfully say “no clouds again last night.” Seeing no clouds is scientifically interesting, and she dutifully wrote papers and indeed an entire chapter of her Ph.D. thesis demonstrating and trying to explain this years-long lack of clouds. But, really, I understood. Explaining a lack of something is not nearly as satisfying as actually getting to see something happen. As her advisor, I would have been happy to fly to Titan to perform a little cloud-seeding, but no one had yet figured out exactly what chemicals or incantations might do the trick.

On April 14^th last year, Emily walked across the Caltech campus to finally turn in her thesis. Then she did what she did most mornings: she walked to her office, downloaded the data from the night before, and checked to see if Titan had clouds. That morning, I suspect, she came close to falling out of her chair. She was likely exhausted from those final stretches of thesis writing, and I am sure that the first time she plotted her data she did what I always do when I see something astounding: she assumed she had made a mistake. She probably re-downloaded the data, double-checked the coordinates, and shook herself a little more awake. But it was no mistake. Titan suddenly had the largest cloud system seen in years. She likes to say it was Titan throwing a graduation party for her. But I know better: I think Titan likes to hide its secrets as long as possible, and knew it was finally safe to let go.

The scientific paper that Emily wrote along with Henry, Tapio, and I that appears in Nature describes the big cloud outburst and its scientific implications. And the implications are pretty fascinating. This big cloud outburst – the biggest ever seen – began in the tropics of Titan, where it has been speculated that clouds, if they ever form, should be weak wispy things. The tropics are where, of course, the Huygens spacecraft that landed on Titan took dramatic images of things that look like stream beds and shorelines and carved channels. How could those be at the equator if there are never clouds and never rain? People asked.

This discovery doesn’t actually answer that question, because we don’t know why there was a huge outburst of clouds in the tropics of Titan. But it does perhaps answer that lingering question: How could those be at the equator if there is never rain? Because there is rain.

Now, however, I am going to allow myself to speculate a bit more than we were comfortable speculating in the scientific paper. I am going to ask: Why? Why were there clouds in the tropics? Why did they appear suddenly at one spot? What is going on?

What I think is going on (again, I warn you, rampant speculation follows…) is that Titan occasionally burps methane, and I think Emily found one of the burps. For many years scientists have wondered where all of the methane in Titan’s atmosphere comes from, and, I think, here is the answer. The surface occasionally releases methane. Call it what you want. Methane geysers? Cryovolcanoe? Titanian cows? Whatever happens, the methane gets injected into the atmosphere and, at that location, instantly forms a huge methane cloud. Massive rainout ensues downwind. The stream channels, the shorelines, and everything else in the otherwise desert-seeming regions are carved in massive storms.

Evidence? Evidence? Where’s the evidence? You scream. Fair enough. I am giving you a snapshot of how science is done, and, at this point, this is the hypothesis stage. Or hunch. Or speculation. This hunch is the type that then guides what we go off to try to observe next. What will we see? Will the spot Emily found burp again? That would be pretty striking confirmation. Will other spots blow? (I should mention that we do indeed think we saw a different spot burp a few years ago).

At this point we have observed Titan well for about 7 years, from the winter southern solstice until the northern spring equinox, which actually just occurred last week, the terrestrial equivalent of late December to late March. What will the rest of the year reveal? We’re still watching, waiting. Maybe in 23 years, when we’ve finally seen an entire season, we’ll call it a day.

Last week I wrote about the International Astronomical Union (#IAU) General Assembly taking place in Rio de Janeiro, to which I was headed. Most people, if they even ever heard of the IAU only know it for its role in the demotion of Pluto at the last General Assembly three years ago. Even I was not entirely sure what to think. I’m not a member of the IAU (mostly because I have never quite gotten around to filling out some form at the right time) and had never gone to one of the General Assemblies before (including the infamous one three years ago where Pluto was discussed; I was instead on vacation in the San Juan Islands outside of Seattle). I have had my share of frustration with the IAU bureaucracies in everything from the stupidity of the way they originally tried to ram Pluto-as-a-planet down the reluctant throats of astronomers (to which the astronomers, who will thus always have my admiration, revolted) to their ridiculousness of their official list of dwarf planets (I will rant about that at a later date, no doubt), to their shameless lack of interest in resolving – one way or another – a case which was either egregious scientific fraud (against me) or equally egregious scientific bullying (by me).

My intention in Rio was simply to go to the special scientific sessions on Icy Bodies in the Solar Systen (somewhat of a specialty of mine) and avoid any IAU-ness. In my mind it was simply yet-another large scientific meeting, this time spread over too much time (two weeks! far too much time to take away from the family), and too many topics (the solar system to the edge of the universe and everything in between and then more). I went, though, because I had been invited to give an extended talk on dwarf planets, and because I thought there might be Pluto shenanigans that I didn’t want to miss out on this time.

I think it is fair to say that I went in with a bad attitude.

Reflecting about all of this on the flight home this morning my main reaction is a little bit of sadness that it took me two or three days to come to the realization that there were amazing things being talked about in every little corner of the IAU meeting. Yes, I learned about icy bodies: the delivery of water to the early earth, the potential interior structure of Titan, the presence of things that look like comets in places that should be reserved for asteroids. And I got to ask some colleagues a few key questions that had been nagging me. (Is it possible that in the early solar system things from the Kuiper belt got mixed out to the asteroid belt? I, unfortunately, was told “no.” Scratch one idea I had off the board.) I even got to finally meet some colleagues from Brazil and Uruguay who rarely get to travel to major meetings, and we talked about future projects we might do jointly.

All of this was good, but not the part that I am flying home most excited about. I am most excited about the incredible number of people who were at the meeting who were enthusiastically and dedicatedly going to talks about astronomical education, about astronomy in developing countries, about preserving the night skies, about using 2009, the International Year of Astronomy (IYA), as a platform for building and keeping the momentum of public engagement. There were posters with pictures of IYA activities in every country I had ever heard of (and even, I will admit, a few countries that I had to ask, um, exactly where they were). And the people doing all of this just seemed beyond themselves with the excitement of astronomy. None of the typical scientific meeting snarky chatter of “well, sure, that was an OK talk, but really he should have cited the work of her and him and them” or “possibly interesting, but I don’t think I would be willing to jump to such a conclusion with such shoddy data” or “let’s not bother waking up early to hear that same talk of her’s yet again.”

It’s great being a professional astronomer and a professor. It’s hard to imagine any job that I could have that I would enjoy more. Yet, regardless of how much I love what I do, there are aspects of it that are simply a job. And like any other job there are parts that get tedious. And like most other people, when parts get tedious I get cranky. My Ph.D. students at Caltech have figured this out quite well. One of the necessary evils of being an astronomer is having to write proposal after proposal after proposal, and, according to the lore passed down from student to student, I become quite irritable approximately two days before any proposal is due. They know that it is best not to come into my office with a seemingly trivial question at times like that.

Concrete [I hope] postscript:

OK, I’m not just going to keep the program booklet, I’m going to try to get into the act. I had a long conversation one evening with an inspiring woman who is involved in more interesting things than I can imagine but who appears particularly excited about bringing astronomy to parts of Africa where there is little to none. She wants to try to set up asteroid-naming art projects for African school children. I can provide asteroids that need names; she knows what to do in Africa. I say hey, @carolune, let’s go. Stay tuned….

Three years ago, in Prague, astronomers had perhaps the most contentious gathering in modern astronomical history. Usually the International Astronomical Union meeting is nothing but a once-every-three year's chance for astronomers to advertise their latest discovery or newest idea while spending some time in a nice international destination, having dinners with old friends and catching up on their celestial gossip. On the final day of each meeting, in a session attended by almost no one, resolutions are passed, usually all but unanimously, on such pressing topics as the precise definition, to the millisecond, of Barycentric Dynamical Time (I have no idea what this actually even means, but, presumably, it matters critically to someone).

The meeting three years ago was different. The usually placid astronomers had spent their time in Prague arguing and bickering day and night about Pluto and about planets and about how to reconcile the two. While several of the typically unintelligible resolutions were indeed to be voted on this last day, the final two resolutions would be all about Pluto. The usually sparsely attended final session was full of surly astronomers itching for a fight.

Everyone by now knows the outcome. In an overwhelming vote, astronomers agreed to tighten the definition of the word “planet” to mean, essentially, the large dominant things in the solar system. Which Pluto is not. That was the end of Pluto as a planet. That was the end, too, of Eris (the slightly-larger-than-Pluto iceball that I discovered that had precipitated the mess) as a planet.

The solar system makes more sense now, and, in three years most people have come to terms with the new solar system. But not everyone (as an example, read the inevitable comments soon to follow this post….).

Three years ago, when the vote put Pluto into its proper place, some vowed to carry the fight forward. “Onward to Rio!” they cried.

It’s three years later, and it is time, once again, for the Internation Astronomical Union meeting, this time in Rio de Janeiro The meeting. It starts tomorrow and I am currently staring out across Copacabana beach watching the winter waves pound the shore (Winter? Only sort of. The beach is packed and the clothes are skimpy) waiting for the real fireworks to begin.

But will there be any? There is an entire weeklong program called “Icy Bodies in the Solar System” with talks about the Kuiper belt, comets, icy satellites, dwarf planets, and even one talk about Pluto. But nowhere is there slated to be any official discussion about Pluto. Will it happen anyway? Will the partisan defenders of Pluto try to storm the meeting in protest to finally have their day in court?

It would be the right forum, for sure. Because of the special program, many of the astronomers who think deeply about planets and the outer solar system are here. Why not ask?

I predict that by the end of the week, the topic of Pluto and planets will come up, at best, only outside of the actual meeting over a few glasses of caipirhina. I suspect no one will press the fight about Pluto because even the partisans are reluctantly admitting to themselves that the fight is over and planets have won.

After the vote three years ago the Pluto partisans tried every trick and argument they could come up with to convince people that the IAU vote had been ill conceived or procedurally wrong, or poorly attended or anything else. All of that could have been fixed by now and a new vote could be taken. Except that Pluto would lose again. And new excuses would be needed (how about: the moon was full and astronomers became lunatics!).

Will they actually give up? I suspect not. It’s easy enough to keep the controversy alive in the media long after most serious scientists have moved on to better things. But I think the fighting will all be guerilla style these days.

But don’t give up hope! Perhaps something will unexpectedly spill into the open and Rio can turn into a place as fun as Prague. Stay tuned….

For entertainment, and should anyone care, I am (sigh) tweeting the IAU meeting. You can follow me at, appropriately enough, http://twitter.com/plutokiller