Mike Brown's Planets: 2009

A ghost of Christmas past

Five years ago I was sitting at work in that quiet week between Christmas and New Year’s Day desperately looking for the 10^th planet. I had made a bet five years before that that I would find a new planet by Dec 31, 2004. Time was running out. I was about to lose. I hate losing. So I was searching and researching all of the pictures of the sky I had taken over the past two years hoping that maybe somewhere in those old pictures was something that I had missed. Maybe there was still a planet to be found after all. Maybe I wasn’t going to lose my bet.

Just 3 days after Christmas I came the closest I had ever come. There was something in the old images that had been missed the first time around, and it was bright. I sent email to Chad Trujillo and David Rabinowitz, the two other astronomers I worked with, saying that this new object was so bright that it might well be twice the size of Pluto. Or bigger! Being right after Christmas, we of course called the object Santa.

Santa, which now goes by the official name of Haumea, we now know to be only about ½ the size of Pluto, and we call it – and Pluto – a dwarf planet rather than a planet. But back in those last days of 2004 when the discovery was first made, we had no idea where all of it was heading.

Our understanding of the Kuiper belt has changed dramatically in these past five years. The best example of this change comes, I think, from the discovery of a large Kuiper belt object that was announced just a few days ago. For me it was a particularly surprising discovery. For the first time I was not at the receiving end of a telescope making the discovery, I was at the receiving end of an email asking me about this new object called 2009 YE7.

“Never heard of it,” I thought.

But, by decoding the numbers, I could tell it was something that had just been discovered a few days before. Like anyone else, my first attempt to know more was a quick trip to Google.

Ah ha! A new large Kuiper belt object found from a telescope Chile, by David Rabinowitz! Yes, the same David Rabinowitz from the Haumea discovery. He has moved on to Chile to try to make newer discoveries from there, discoveries in parts of the sky that we didn’t look at back when we were working at Palomar Observatory outside of San Diego.

Based on preliminary information, it looked likely the 9^th largest Kuiper belt object ever found. David was clearly on to something good here.

I didn’t have time to delve into any more details because all of this had occurred as I was sitting in a movie theater waiting for the start of The Princess and the Frog with Lilah. She loved the part before the movie started because she could watch the on-screen ads. I checked my email and found out that there was a large Kuiper belt object that someone else had discovered. Then the movie started. I was itching to get more information about 2009 YE7, but I allowed my mind to drift down the bayou instead.

After the movie, though, my mind set to work on the implications of this new discovery. Based on its brightness it might well be a perfect size to test one of my new theories about medium-sized Kuiper belt objects. I feel like I now understand the largest objects, and I fear that I will never understand the smallest objects, but the middle ones are within grasp, if we can just find a few more to test some pet theories about them. For 2009 YE7 to be a good candidate for my theory we need to know if it has a moon, what color it is, and what materials are on its surface. Then we’ll see. I started thinking about where 2009 YE7 is in the sky, what telescopes I could use to point at it, how to time the observations.

Even as I was thinking these thoughts, my mind was drifting back to the discovery of Haumea exactly five years earlier. Back then, on the day of the discovery, we knew absolutely nothing. I had no good ideas about what Haumea would be like; I had no theories I was testing, no hypothesis to work out, no predictions to boldly claim. We were simply in the very early stages of exploration to see what was there. The exploration was going well! Soon after the discovery of Haumea, we tripled the jackpot by first discovering Eris – the one we now know to be larger than Pluto – just two weeks later, and then Makemake – the one we now know to be just a bit smaller than Pluto – a few months later. I felt the universe was exploding with new bright Kuiper belt objects and possibilities were endless. We didn’t know anything about what these objects were, how big they were, what they were made of, or what had happened to them. In April 2005 I still believed it possible that they were all 3 larger than Pluto and that they would eventually be called the 10^th, 11^th, and 12^th planets.

In the five years since, we’ve learned a tremendous amount. We determined their sizes and gave up on any of the things in the Kuiper belt being planets (I lost my bet, too). We found Haumea’s two moons; we found that it had a surface that looks like an almost perfect glaze of ice; we found that it was white, again like ice, we found it elongated and spinning end over end every 4 hours, and we found a cloud of other smaller objects on similar orbits. We found that Makemake is covered in thick layers of frozen methane, that Eris is bigger and heavier than Pluto, and, most importantly, that things were beginning to make sense. We had moved from exploration to explanation. Haumea’s strange properties – and that cloud of objects in similar orbits – were all a consequence of a giant impact 4 billion years ago or so. Eris and Makemake were large enough that they should have methane on them.

With our new found knowledge even things that had been discovered earlier were finally being put in context. Quaoar is a weird combination of Haumea and Makemake. Orcus is what Makemake would look like if it were just a little smaller. Varuna is, well, Varuna is still confusing.

Mostly, though, now instead of each object being an individually mystery to be solved, each new object is a piece of a puzzle where many of the pieces have already been put into place. With only a little information, we can guess where the piece likely goes.

Which brings me back to 2009 YE7. Five years ago, its discovery would have been a thorough mystery to solve. But when I first heard of it two days ago, it was, instead, potentially the exact area of the puzzle I had been looking to fill in. I thought it was going to be that perfect medium-sized Kuiper belt object to try out my theories. I just needed some telescopes, some computers, and some time, and everything would fall into place. I thought it would be a fun month or two to try to collect and analyze the data quickly.

I was wrong. It took me about 2 minutes to figure out almost everything that there is to know about this object and its violent history.

When I finally got home and got a chance to look a little more closely (and “a little more closely” here doesn’t mean much; as of today still nothing is known about the object except for its position for about the past two weeks), I realized two things that told the whole story. First, 2009 is YE7 bright. In absolute terms, it is the 9^th brightest object, which is what led to the reasonable assumption that it is likely the 9^th largest object (by absolute brightness here, I mean the brightness things would have if they were all the same distance away; some objects are bright just by virtue of being close). Second, the orbit of 2009 YE7 is tilted relative to the planets by 29 degrees. Following the position of an object for only 2 weeks doesn’t give you a precise measurement of much about its orbit, but that tilt is one thing that is solidly known even with this limited data. An angle of 29 degrees is an unusually high angle. Not too many objects are tilted by that much. But one that is is Haumea. Ah! Haumea! Haumea with its family of shards all going around the sun on orbits just like it. Tilted by 29 degrees.

2009 YE7, the brightest object discovered in the Kuiper belt in almost 5 years, is almost certainly one of the large shards (perhaps even the largest) blasted off of the surface of Haumea 4 billion years ago. 2009 YE7 and the other shards have been circling the sun on their own ever since. It is bright not because it is particularly large, but because all of the fragments of Haumea have extremely bright, reflective, icy surfaces which make them stand out against the more common darker Kuiper belt objects. 2009 YE7 is not the 9^th largest Kuiper belt object; it is probably about 440 km in diameter and so in the top 50.

I will admit that I miss the old Kuiper belt. I miss the mystery and wonder of exploration of unknown territories. There will be nothing like it in solar system studies for a long time to come, I suspect. Perhaps ever. And yet, as much as exploration is thrilling and exhilarating, there is something deeply satisfying about learning about a new bright Kuiper belt object while sitting in a movie with your daughter and understanding most of its 4.5 billion year history soon after getting home. We’ve learned so much. We’ve come so far.

….

A technical aside on 2009 YE7. The tilt of the orbit alone does not prove it to be a Haumea fragment, particularly since the other parameters of the orbit are still poorly known. Above, when I say it is “almost certainly” a fragment, the assessment is a judgment based on experience, rather than a scientific fact. But I’m pretty confident, sufficiently confident that I’d be willing to bet (I need to win back some of my loss from that old 2005 bet, right?). The real confirmation, though, would come from an infrared spectrum that shows evidence of deep water ice absorption features, but that requires a pretty big telescope. Almost as good, though, would be optical colors showing it to be white (solar-colored, really) like all of the other Haumea fragments. Measuring these colors is actually quite easy; all you need is a ~1 meter telescope and ~1 night of observing. Any two photometric bands would be good. I would probably just try V and R. Then measure a solar colored standard star and compare. They will be the same, I predict. Go do it! Tell me the answer! It’s fun to make predictions, and even more fun for them to come true.

…….

I don’t actually think the exploration is finished yet. The southern skies are still largely terra incognito for the Kuiper belt. David Rabinowitz has clearly just started the journey; others are scanning out there, too. Much of what they find may indeed fit into the frame of the puzzle that we already know, but I still hope some day to open up some email and read about some new discovery and sit stunned realizing that someone just found something that I didn’t expect at all.

Happy Solstice

[an encore, from a long ago Solstice. but still true today]

If you had walked out into my backyard around 4:40 the last few afternoons you would have been greeted with the orange ball of the sun setting with a final low glare over the tops of the buildings that I can see low on the horizon out across the Los Angeles basin. At this time each late afternoon I like to get out the binoculars that I keep next to the back door, and I step outside to watch the last seconds of the sun setting and to find the spot where the last glimmer of light for the day appears. Every night that glimmer has moved a little further to the south. Just a few weeks ago the last glint vanished just behind the cupola of the Pasadena city hall. By just the next day, the cupola was clear, but the sun disappeared behind the building to the left of city hall. Last night it set 4 or 5 office buildings further to the left, still, behind an anonymous office tower that I can't recognize, but through the binoculars appears impressive with the sun directly framing it and the occasional stray bit of light going through a window on the far side, rattling around on the inside, and emerging as the last bit of bit of light before a long winter night. Tonight I watched again, and the sun set behind exactly the same anonymous tower. It hadn't moved at all. Today, therefore, must be the solstice. The solstice is many things: the first day of winter, the earliest sunset, the longest night of the year, the latest sunrise. Most people notice the sunset more than anything else. But solstice comes from the latin "solstitium": sol for sun, and stitium for a stoppage ("armistice" comes from the same root: a stoppage of arms). The stoppage of the southern progression of the sun -- the turnaround to come back to the north -- was considered a big enough phenomenon to give the event its name. The sun stoppage. As the darkness tries to ascend (quickly; these winter twilights don't last) the other part of the season becomes clear. While the nearby glare of Los Angeles means that we never truly have darkness in these parts, this time of year everyone is doing their best to cut the darkness even more. I can see Christmas lights on the houses throughout Pasadena, and, with the binoculars, I can see to downtown Los Angeles where the buildings have been strung with lights. And who can blame them? With the nights so long and the sun moving further and further south, who would not want to try to do their part to make up for the absence of the light and the heat? Who would not be at least a little afraid at this time every year that the sun would somehow not decide to stop and then come back?

At our house we celebrate the solstice with our best attempt to coax back the sun. When the night is as dark as it will get, we gather with friends around our Christmas tree, turn out all of the lights in the house, and slowly refill the house with the yellowy-orange glow as we one by one light the dozens of candles hanging in the branches of the tree. Lighting candles on Christmas trees is a well known Bad Thing to Do, but we find that with a tree cut down the day before (and a fire extinguisher on hand just in case), all goes smoothly. Like the sun, the candles slowly go out. Some catch a few warm drafts and burn more quickly, some get less air and burn more slowly, but one by one they all eventually go until, with just two or three left, the house is dark again and the shadows of branches shimmer sinisterly on the ceiling. Finally the last candle sputters and dies, sometimes with a long glow and sometimes with a sudden final pop, and the longest night of the year totally envelopes us.

The night sky gets in on the act this time of year, too. Many people who claim to know no constellations in the sky can look up and identify Orion in the winter sky. With the three bright stars making the belt, the scabbard of stars hanging below, and the quartet making the shoulders and knees, Orion is truly simple to identify. But Orion is also composed of some of the brighter of the stars in the sky. In fact, look outside, and look around Orion. Bright stars are all around. The constellation of Taurus, Sirius, the brightest star around. The seasons of the sky are not created equally. Winter is a spectacular display of stars and constellations unlike any other, as if the stars, too, are trying to help us out on the longest winter nights by saving the best show for the very end of the year. None of this is true, of course. The spectacular winter skies are caused by the fact that we are looking straight in to the Milky Way galaxy, instead of out of it as we do in the spring and fall. But still, it is hard not to see the similarity between the lights strung in the town below trying to dispel the night and call back the sun, and the lights above, also seemingly strung for the same reason.

Tomorrow, if the weather holds, I'm going to go outside with my binoculars and see exactly where the sun sets again. Because I do this every year, and because I can look up the precise date and time of the solstice, and because I know that the earth will continue to go around the sun with the same tilt for my entire lifetime, I know what will happen: the sun will have moved away from the anonymous office building and finally started moving right again. The day will get imperceptibly longer. Really, there is not much suspense in what will happen, just a certain reassuring inevitability. But if I didn't know these things and didn't have confidence in the inevitable, I can imagine myself holding my breath as the last rays of the sun were shooting out and I was trying to see just where it was setting. I stopped yesterday, but is it really turning around today? Will the days really get longer again? Will my crops (well, ok, my vegetable garden) come back to life? And I'll then see the spot and it will be clearly north and I'll know. And at that point, I will say to anyone within sight: happy new year. For while the calendar claims I have another week to go, the Christmas lights and the candles and Orion and Taurus and Sirius will have done their jobs, and the sun will have started its new year already today and we should all be glad for the solstice.

The end of the fall

The fall term always gets a little overwhelming, as classes get into session and lectures need to be written, problem sets graded, exams created. I have an amazingly long backlog of things about which I want to write at this point but which I have not yet had the time to even get started. To top things off, my life appears to be changing forever. Most of these pieces get written on weekend afternoons while Lilah is napping. But the days of napping appear to be coming to a close.I understand intellectually that this is likely, after all, few 10 year olds nap, but I had never really stopped to think about the effect on my life. It’s not all bad; being able to pondering going out to do something with Lilah in the afternoon could be quite fun! But it will definitely gobble up my quiet afternoon writing time. But, today, after a late Halloween night and a no-doubt sugar-induced-early-morning wakeup, Lilah is currently snoozing away and I am going to now type as quickly as possible. Ready? Go! (Halloween? Yes, I started writing this almost a month ago, giving a perfect demonstration of the point I am trying to make.)

Back at the end of August I asked everyone to review my paper on Titan fog, and, to my surprise, many people took the task extremely seriously. The paper was discussed in classes and in on-line forums and was stared at by many eyes. If you recall back in August one of the reasons for attempting this open review was the fear that having only a single official reviewer leads to a huge random factor as to whether or not you will get anything useful out of the process. In this case, I have to say that the official review was pretty difficult to decipher. The reviewer commented on a few typos, complained about the location of the references, and said that the paper was generally incomprehensible.

Incomprehensible? Now, I will admit to having written papers that are incomprehensible before (how about this one; I can barely understand it myself 20 years later), but I actually thought that the paper was pretty clear. What’s more, of the many comments I had gotten from outside the official review process, no one had quite said “incomprehensible.” So what was going on here?

I reread the paper several dozens of times, and reread all of the comments that I had gotten, and realized, I think, the source of the problem. I think I was much too terse in my explanation of what I had actually done. Sure, I discussed fog and its discovery in gory detail. But I perhaps did not do a great job of describing how I really sorted through all of the data to find fog. It’s a pretty crucial step. If you don’t provide enough details in your paper that someone else could come after you and reproduce precisely what you did, you have failed an important point of having a paper in the first place.

One reason for describing all of this poorly was that the real process was actually quite different from the way I attempted to describe it in the paper. The real process consisted of this: I was looking at a bunch of pictures of Titan and said “Whoa; what the heck is that?” That turned out to be fog. I suspect that many discoveries are made that way, but if you read scientific papers you will rarely learn that fact. If you read my paper, you will find something like “Fog is very important so one fine day we decided to go look for fog on Titan. And we found it.”

OK, partially this description is true. After the first few times of accidentally seeing the fog we did, one fine day, systematically search through the entire data set. But that description was all pretty muddled.

The solution was a nearly complete rewrite of the paper. Had I just gotten the official review I would have fixed the typos and reworded a few things here and there and wondered what the heck the reviewer was talking about, but with the strength of the large number of comments, I could really tell what people were seeing and reading and I could make it significantly better. At least I think it is. But don’t take my word for it. Remind yourself of the first version, here. And now go read the new version here as it is about to appears in this week's Astrophysical Journal Letters. You still will not read the new version and realize that the real way we found fog is that we stumbled on it accidentally, but you will at least, I think, have a better idea of precisely what we did and how we did it. Want to go find fog yourself? I think the roadmap is now significantly more clear.

My conclusion from this experiment? I can’t tell you whether this system will always lead to such dramatic improvements in the quality of a paper, but in this particular case there is no doubt that when you read the two versions of the paper and you note any improvements almost all of those improvements came from the open review, rather than the official review. All of the comments that were sent to me were incorporated in one way or another. And for that, I would like to say a hardy THANK YOU to everyone.

But wait, there’s more!

Fresh on the heels of the Titan fog paper, I have submitted a paper to the Astronomical Journal called “The size, density, and formation of the Orcus-Vanth system in the Kuiper belt.”

This paper, I will admit, is less accessible than the paper about fog on Titan, yet, still, would you give it a read? It’s been posted online for a week and one reader already pointed out a rather stupid math error (thanks Alan Martin) of the sort that creeps into papers when you work on them one hour a week for 3 months (the error is still there, until we fix it in the next round of reviews, so feel free to go track it down and marvel at how stupid I sometimes can be).

Normally I would spend a few pages here telling you what the paper is about but, conveniently, I did that last spring, when we were searching for an appropriate name for the moon of Orcus. Go back and reread the post about coming up with names for the moon of Orcus, where I talk about the strange characteristics of what we now call Vanth. And, with a bit of continued Lilah napping over the weeks to come, stay tuned for thoughts about searching for the real Planet X, why I hate the 5 dwarf planets, and strategies for Lilah-weekend-nap-inducement.

And look! Lilah is done with her nap, and ready to start in on last night’s candy. Back to the sugar frenzy. (and with that, Lilah was awake, and we were off, and now it is a month later and Lilah is settled into a post-Thanksgiving nap and I finally have a spare moment to finish and post. Classes end next week for the year, so I look forward to a bit more time for reflection soon. Stay tuned.)

P.S. on the problem with science

I should have, of course, provided the two papers in question so you can decide for yourself. I can't quite do that. I can give you the link to my paper, here:

And I can even provide you with a link to their paper:

But it's possible that you can't read theirs. (but wait: read the comments below; people found all of the parts of this article posted online in various locations, so you're in luck!) Why not? Because, even after $1B of taxpayer money going to send Cassini to Titan and get these results, the copyright to the paper is now owned by Nature. And they say you're not allowed to read it unless you subscribe or pay. If you are logged in from an academic institution, you probably will get access from their subscription. But if you're elsewhere you are simply out of luck. Seems a bit crazy, huh?

If you do get the two papers, be sure to check out the supplementary information in the Nature paper: that is where all of the important details (like where there are and are not clouds) lie. At first glance the two papers look more or less like they say there are clouds in the same spots. It helps that the figures are all really really small so details are hard to discern. But when you blow them up and look carefully things just don't match up nearly as well as two papers using exactly the same data should.

The problem with science

Science is a great system. You examine reality, come up with ideas how it might work, test those ideas, keep the good ones, discard the bad ones, and move on. It’s got one big flaw, though, and that is that science is done by scientists, and scientists are people.

I have a whole slew of scientists mad at me this week – and I will admit that I am pretty irritated back – because none of us cool rational analytical scientists can truly separate our emotions and our egos from the reality-based science that we do. In this current dispute, I get to claim the scientific high ground, at least. My scientific paper that just came out this week unarguably demonstrates that their scientific paper has some rather embarrassing errors. But, in the end, I suspect that even with that seemingly unassailable high ground, I lose the war.

The papers in question are both on the mundane side. They both are catalogs of where the Cassini spacecraft has and hasn’t seen clouds on Titan over the past 4 years. Papers like these, though not going to make headlines anywhere, are nonetheless important contributions to understanding what is going on (at least I think so, or I wouldn’t have taken the time to write one!). Without complete and accurate catalogs of things like where there are clouds on Titan, we cannot begin to understand the more profound questions of why there are clouds on Titan and what does this tell us about the hydrological cycle on the moon. These papers don’t try to answer these questions, but they are necessary pieces of the puzzle.

You would think that two papers that examine the same set of pictures from the Cassini spacecraft to map clouds on Titan would come up with the same answers, but they don’t. And therein lies the root of the problem. When the main topic of a paper is where there are and aren’t clouds on Titan and you sometimes say there are clouds when there aren’t and there aren’t clouds when there are, well, then you have a problem. They have a problem, since theirs is the paper that makes the mistakes. So why are they mad at me? I think perhaps I know the answer, and, perhaps I even think they might have some justification. Let me see if I can sort it out with a little of the convoluted history.

I started writing my paper about 18 months ago. A few months later I realized the other team was writing the exact same paper. Rather than write two identical papers, I joined there team and the two papers merged. The problem was that as I worked with their team through the summer, it became clear that their analysis was not very reliable. I spent hours going over pictures in details showing them spots where there were or were not clouds in contradiction to their analysis. Finally I came to the conclusion that their method of finding clouds and thus their overall paper was unsalvageable. I politely withdrew my name from their paper and explained my reasons why in detail to the senior members of the team overseeing the paper. I then invited them to join me in my analysis done in a demonstratively more accurate way. The senior member of the team agreed that it seemed unlikely that their method was going to work and he said they would discuss and get back to me.

I felt pretty good about this. I had saved a team of people who I genuinely liked from writing a paper which would be an embarrassment to them, and I had done it – apparently – without alienating anyone. I remember at the end of the summer being proud of how adeptly I had navigated a potentially thorny field and come out with good science and good colleagues intact. Scientists are usually not so good at this sort of thing, so I was extra pleased.

I never did hear back from them about joining with me, so when I wanted to present the results of the analysis at a conference in December, I contacted the team again and asked them if they would like to be co-authors on my presentation in preparation for writing up the paper. I was told, no, they had decided to do the paper on their own. Oh oh. I though. Maybe things won’t end up so rosy after all.

Their paper came out first, in June of this year, in the prestigious journal Nature of all places (it’s not hard to figure out the reason for the catty comment often heard in the hallways “Just because it’s in Nature doesn’t necessarily mean that it is wrong.”). I was a bit shocked to see it; I think I had really not believed they would go ahead with such a flawed analysis after they had been shown so clearly how flawed it was (and don’t get me started about refereeing at this point). Our paper came out only this week, but, since their paper was already published, one of the referees asked us to compare and comment on their paper. I had avoided reading their paper until then, I will admit, because I didn’t want to bias our own paper by knowing what their conclusions were and because – I will also admit – I was pretty shocked that they had, to my mind, rushed out a paper that they knew to be wrong simply to beat me to publishing something. I hoped that perhaps they had figured out a way to correct their analysis, but when I read their paper and found most of the erroneous cloud detections and non-detections still there, I realized it was simply the same paper as before, known flaws and all.

So what did I do? In my paper I wrote one of the most direct statements you will ever read that someone else’s paper contains errors. Often things like that are said in couched terms to soften the blow, but, feeling like they had published something that they knew to be wrong, I felt a more direct statement in order.

And now they’re mad.

Reading all of that I certainly hope you come to the conclusion that I am 100% right and they are 100% wrong. You’re supposed to come to that conclusion because I wrote the whole thing from my own biased perspective. And I have my emotions and my ego in there. And I feel wronged.

I’m going to try an experiment from their point of view and see if I can see where I went wrong and irritated them.

Last summer they kindly invited me to be part of their paper, and they shared their non-publicly released data with me (though neither analysis made use of it). They fixed many of the errors that I identified that summer and honestly believed the paper was now good enough. They knew that the analysis wasn’t perfect, but felt like they had invested significant resources in the analysis and that the overall conclusions were correct. So they submitted the paper, and it got accepted in Nature, and they were pretty proud of the effort. Then, out of the blue, my paper is published that says in unusually direct words that their paper is not to be trusted.

Here are some reactions I can guess that they might have had:

(1) Mike Brown’s complaints about are paper are simply sour grapes because our paper came out first and in a more prestigious journal. He is trying to attack our paper so that his paper, which lost the race, somehow seems relevant.

(2) Mike Brown is a nit picker. If you look carefully you will find that while the details of the cloud maps are different between the two papers, the overall conclusions are largely the same. In the end, the conclusions matter, not the details like this.

(3) Mike Brown is a betrayer. He learned about our analysis last summer and then tried to use what he learned against us.

(4) Mike Brown is an impolitic ass, and even if he had concerns about the paper he aired them in an unkind way and now we detest him.

And now I must in the end admit that one of those is actually true. I plead guilty to (4). (1) and (3) are factually incorrect. (2) is bad science (yes: the details matter, not just the conclusions). But (4)? Yeah. OK. Probably. That’s the problem with science. All of those scientists. And few scientists are renowned for their social skills. Even me.

So there are some things that we can all agree with, and some things that we might disagree with. Reality admits little room for differences of opinion. Interpretation of reality, though, is always more subjective.

Everyone should agree: The paper that was published in Nature this June is at times incorrect about where there are and are not clouds. This is simply reality and not open to much discussion (which doesn’t mean there won’t be much discussion).

In my opinion: These errors are fatal for a paper purporting to be about where there are and are not clouds. In their opinion: These errors are not significant and don’t affect the conclusion of the paper. In my opinion my opinion is correct, but I am sure that in their opinion their opinion is correct. Unlikely we’ll come to a conclusion on this one, as this is not about reality, but about interpretation of reality. No analysis is 100% correct and everyone has their own opinion about when an analysis crosses the threshold from mostly correct to fatally incorrect. We have differences of opinions on where this threshold sits, obviously.

In their opinion: The statements in my paper discussing the problems with their paper are disproportionately harsh. In my opinion: The statements in my paper discussing the problems with their paper are harsh, but proportionate to the flaws in the paper. But I will admit that this is the part I am the most uncomfortable with. The statements in my paper are harsh. Maybe too harsh. Did I let too much emotion and pride come in to play as I wrote them? Probably. But as I wrote those statements I was fairly appalled at what seemed to me a lack of concern with reality on the part of their paper. Everyone makes mistakes in scientific papers. Sometimes even big ones. But I had never come across a paper where the mistakes were pointed out before the paper was submitted for publication and the authors had not fixed them. Again, though, my opinion is colored by the fact that I find their analysis fatally flawed. Their desire to go ahead is colored by the fact that they find their analysis good enough.

In their opinion: Mike Brown is a detestable ass. In my opinion: They are shooting the messenger for delivering a message that they already knew. But perhaps both opinions are correct.

Sadly, for me at least, I tried really really really hard to make this work. And to me, “make this work” meant make sure that any papers published which described clouds on Titan were factually correct while at the same time not alienating my colleagues. I failed at both.

So I think we end with this:

The other team will probably always think I crossed a line by writing so harshly of their paper. I will probably always think that they crossed a line by publishing a paper they knew to have factual errors.

Who is right? Probably both. I suspect they let their egos and emotions allow them to care more about publishing a paper in Nature than whether or not that paper was correct. I suspect my ego and emotions caused me to write more harshly than I needed to. That’s the problem with science. It’s done by scientists. Scientists have all of those egos and emotions just like everyone else and no one has figured out a way to leave them at the door when you walk in your lab or your telescope or wherever you sit down to write papers.

In the end though, the only losers in this process are the scientists themselves. While all of us are sitting around feeling wronged, reality marches on. If you would like to know where clouds are or are not you can go read an accurate account. But that’s probably the last paper you will read from me in this field, for I am bowing out. The study of Titan was always just my hobby. A hobby that causes this much anguish is not a very good hobby. Time for a new one. I’ll miss Titan and trying to finally figure out what is going on with all of those clouds, but there are many other interesting things out there in the universe. Time to start exploring once again.

Millard Canyon Memories

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.

Fog! Titan! Titan Fog! (and a peer review experiment)

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!

Only final fun part of the story. The fog doesn’t appear to prefer hanging around the one big south polar lake or even around the other dark areas that people think might be lakes. It looks like it might be more or less everywhere at the south pole. My guess is that the southern summer polar rainy season that we have witnessed over the past few years has deposited small pools of liquid methane all over the pole. It’s slowly evaporating back into the atmosphere where it will eventually drift to the northern pole where, I think, we can expect another stormy summer season. Stay tuned. Northern summer solstice is in 2016.

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!

Planetary Placemats

This morning Lilah started asking about Christmas. With her fourth birthday now more than a month behind her it seems to the natural thing to start contemplating. As a warm up, she started trying to remember presents from last Christmas.

“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.

The long road to a Titan storm

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.

Rio roundup

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 intentio

n 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.

As an antidote to crankiness about the job of astronomy or about the bureaucrats of the IAU, I’m keeping my program from Rio with the names of all of the talks and all of the posters from everywhere around the world. Long after I’ve forgotten what I in the invited talk which was the reason I went (“Haumea and her children” was the title, if you must know), I want to still remember all of those people so excited by everything astronomical that they devote their lives not to discovery but to showing it to everyone else.

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….

Don't try to blame it on Rio

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

The first of the Pluto books!

My preview of the reviews for The Pluto Files: The Rise and Fall of America's Favorite Planet by Neil DeGrasse Tyson and The Hunt for Planet X: New Worlds and the Fate of Pluto by Govert Schillng is in the September issue of Physics Today.

Or you can read it here.

Lunar dreams

Forty years is a long time, particularly if you are only a smidge over forty yourself, like me. When I was a kid, I wanted nothing more than to be an astronaut and go to the moon like those guys did 40 years ago today. The father of everyone I knew – mine included – was some sort of engineer working to build the Saturn rockets to send men to the moon (for a while as I child I thought that when you grew up you became a rocket engineer if you were a boy and you married a rocket engineer if you were a girl; few other options in the world appeared to exist). When Neil Armstrong stepped on the moon, I was pretty sure that that was exactly what I was going to eventually be doing, too. I drew picture story books of rockets and command capsules and lunar modules and splash down. I made cardboard models of Lunar Rovers and designed outposts where, I was pretty sure, I would eventually live.

The moon landings have faded into history as simply one of those amazing things that happened a long time ago that we don’t do any more, like dog treks to the south pole, first ascents of unscouted peaks, and world wars.

Every once in a while, though, something happens that pulls the moon landings out of the abstract haze of history and makes me remember: these things were real! They really happened. Here are two:

A few years ago I was giving a talk in New York City at the Hayden Planetarium, and I decided to spend the afternoon visiting the Planetarium itself and the Museum of Natural History. I was particularly interested to see how they were dealing with all of the controversy over Pluto, the then-embattled 9^th planet. And I was mesmerized by the best example I had ever seen of a Pallasite meteorite – a chunk from the boundary between the inner iron core and the rocky mantle of a little dwarf planet in the asteroid belt which got smashed to little bits, one of which I was staring at. But the part of the visit that unexpectedly took my breath away was staring at the pictures that were strewn on the walls of the hallways of the Planetarium with little fanfare. These were full sized prints of pictures taken by the Apollo astronauts, prints so large that you could stick your face right up to them and see details that you would never seen in the typical book or TV show or anything else. And most of them I had never seen before, anyway. There are only a few canonical moon shoots that we have all seen over and over and over but most of the hundreds and hundreds of pictures have not gotten much light of day. And oh what pictures. Standing and staring at those pictures took me back 35 years to when I wanted to be an astronaut. They were really there. You could almost taste the moon dust.

My favorite of all of the pictures, and the one that made me suddenly re-remember how spectacularly far-fetched the whole idea of going to the moon was, was a shot where you could see the lunar rover in the near foreground and way way way way way in the distance was the lander. And suddenly I realized: these two men are so far removed from home that the chance they will ever make it back alive seems miniscule. They are hundreds of yards from the rover, which is miles from the lander, which has to take off from the surface of the moon, rendezvous with the command module, return to the earth, drop out of the sky, and splash down into the ocean. And it all has to work. What were they thinking?

I stumbled across one of my other favorite Apollo moments a few years ago through some sort of random web surfing, looking for I-can’t-remember-what. My eye was grabbed by a link to an annotated transcript of the Apollo 11 landing. I clicked and started reading. I looked up 30 minutes later in a sweat, my heart pounding, and, again, thinking: who possibly thought that this would work? These guys were insane. I was too young at the time of the Apollo 11 landing to have known at the time whether or not people paid attention to how close Apollo 11 came to not making it. And how nail-bitingly suspenseful to know if they were going to land or crash or abort or something else entirely. I won’t give away the ending (perhaps you know it already), but instead simply point you in the right direction. I can read the whole thing over and over again (and pause for all of the audio clips and film clips), but if you feel the need to cut to the chase, start at 102_48_08 with “Eagle, Houston. You’re Go for landing. Over.”

I just did it again. To get the link right here I searched for the page again and while I was at it I read the whole thing. And my heart rate is still going strong.

Just in time for the big anniversary there are a slew of new books about the moon, of course. I recently got two of them to whet my lunar appetite. They both have that ability to make me re-remember my astronaut-yearning days, but each in very different ways.

Who could not like the idea of Moon 3-D: The Lunar Surface Comes to Life? As long as you can get over reading the book while looking through built-in 3D glasses (and thus looking pretty silly to anyone around you, including even 4 year olds), the book is a pleasure to look through. I never realized that the astronauts purposefully tried to take 3D image. They didn’t have any of the bulky dual camera stereoscopic equipment that people usually use, they simply took a picture and then moved left or right a few feet and took another. The results range from hard-to-figure-out to spectacular. And the 3D really works most of the time (enough so that after the 4 year old was finished making fun of me for the funny glasses she wanted to look through them herself and she made ooohing and ahhhhin sounds and kept taking off the glasses to make sure nothing funny was happening). A personal favorite of mine is an Apollo 15 picture looking back at the lander with desolate mountains in the background and footprints all around the base. Even with 3D none of the pictures quite has the impact of the large prints on the wall of the Hayden Planetarium, but if you’re not headed into New York anytime soon, this might be the way to relive the moon.

The other book takes a special type of space geek to enjoy. Missions to the Moon, a big glossy book chock full of geeky things like reproductions of Wernher Von Braun’s design for a space station, somebody’s schematic sketch of how an Apollo mission would work, a schematic of the Apollo console with all of the lights and switches indicated, and, my favorite, the lunar module descent monitoring chart, which the astronauts would have used to look out the window and know they were going in the right direction. Couple that with the transcript of the landing itself and see if you can follow the whole thing.

After Lilah got done playing with the 3D glasses she, of course, wanted to know what all of those other things in the other book were, and I explained all about landing on the moon to her. Today, on our drive in to school, we listened to Buzz Aldrin on the radio, and I told her, again, that he was an astronaut who went to the moon.

“Why is everyone talking about the moon today, Daddy?”

And I explained about how on this day, 40 years ago, astronauts landed on the moon.

Forty years is a long and arbitrary time in some ways, but to me, and to Lilah, this was even more meaningful. I am 40 years and 1 month older than my daughter. I remember when Armstrong and Aldrin stepped on the moon 40 years ago today; the things I saw and the things I read and talked about affected the direction of the entire rest of my life. Lilah is, finally, the same age as I was then. What will she remember? Where will she go? No way to know, but I’d like to ask her in 40 years if she remembers a day we looked at books and listened to the radio and tried to remember what it was like 40 years before that when I was a 4 year old watching people on the moon for the first time.

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