A thoroughly sporadic column from astronomer Mike Brown on space and science, planets and dwarf planets, the sun, the moon, the stars, and the joys and frustrations of search, discovery, and life. With a family in tow. Or towing. Or perhaps in mutual orbit.


Showing posts with label sociology. Show all posts
Showing posts with label sociology. Show all posts

The dwarf planet that gets no respect

Quick: name the three largest known objects in the Kuiper belt. If you’ve been paying close attention you will instantly get Eris and Pluto, and, if pressed, you will admit that no one knows which one is bigger. And the third? An unscientific poll of people who should know the answer (my daughter, my wife, my nephew) reveals that not a single one does.

The answer, of course, is Makemake (you remember how to pronounce this, right? Mah-kay-mah-kay, Polynesian style).  Makemake was discovered just months after the discoveries of Eris and of Haumea, and all were announced within days of each other. Eris and Haumea had important stories immediately attached to them (Eris was as big as Pluto! Haumea had suspicious discovery circumstances!), so poor Makemake stayed in the shadow of its more famous contemporaries. It was so overlooked that, in the hastily called press conference in which we announced the discoveries, I couldn’t even remember the official designation of Makemake when asked (it was 2005 FY9, of course; how could I have forgotten that?).





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Posted by Mike Brown on Wednesday, April 03, 2013
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22 comments

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.
Posted by Mike Brown on Sunday, September 27, 2009
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21 comments

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!
Posted by Mike Brown on Thursday, August 27, 2009
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14 comments

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 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.
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….
Posted by Mike Brown on Sunday, August 09, 2009
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7 comments

A winding path

I’m in Tucson this week and right now about to go out to dinner as part of three days of talks and meetings and lunches all in conjunction with me being awarded the Marc Aaronson Memorial Lectureship this year. I do not tend to talk much about things like this because it seems a bit unseemly, but I am going to break my usual silence and tell you why this particular award is particularly meaningful to me.
The award is given every 18 months to an astronomer who makes a significant contribution to observational astronomy at a young age. I’m happy they didn’t check the birth date on my driver’s license. The lecture itself was last night, at the University of Arizona, and I began my lecture with a story I have never told anyone before. I said something like this:
There are several reasons why I am quite flattered and honored to be receiving this award. First, the list of the people who have received the award over the past two years is particularly impressive. It is thoroughly flattering to be considered to be in the same company as people who I think of as superstars in the field. It’s also gratifying to receive such an award from what I still can’t help but think of as “real astronomers.” Astronomers who study the solar system have long been considered the ugly step-sisters of astronomy. Nobody really wants to give us telescope time or accolades or awards. In fact, we had to set up our own societies so we could give each other awards and not feel totally left out.
Both of those reasons for being honored to receive the award, however, would be reasons I could give no matter what the award was. But, to me, receiving the Aaronson award means even more.
When I was a senior in college in 1987 [which, by the way, means I just had a 20th college reunion, which I am pretty sure disqualified me from being considered “young”] I found what I thought was going to be the field in which I was going to make my career. I had been doing research projects with physicists who were interested in the large-scale structure of the universe – where galaxies are, why they have the distributions they do – and I thought that that was about the most interesting thing that any human could possibly study. The only problem with the projects on which I was working was that there were more theoretical or computational than observational. I wanted to be someone who went out to telescope and collected data and discovered things myself. I didn’t want to just sit in the computer lab in the basement and make endless computer models about how the universe might be, I wanted to go out look at the night sky and figure out how it actually is.
Nobody did that at my university, so I started looking around to see if anyone did that anywhere. Every time I looked up the topic or anything related, a single name would always pop to the top: Marc Aaronson. Aaronson was an astronomer at the Steward Observatory at the University of Arizona, and he was doing exactly what I wanted to be doing. I decided that what I really wanted was to be Marc Aaronson, but that, since this seemed unlikely, I was going to go to graduate school at the University of Arizona and I was going to work with Marc Aaronson.
That spring, Aaronson was crushed to death by the dome of telescope where he was working.
I decided maybe I wouldn’t go to graduate school. I went biking around Europe instead.
The following year I was ready to go, but Arizona didn’t seem right anymore. I ended up at U.C. Berkeley working with someone who did generally similar research on distant galaxies. Which, through a path that is convoluted to explain but extremely clear in my head, led to my Ph.D. thesis on the magnetosphere of Jupiter and my current work on the outer solar system. Which led me to Tucson, to receive the award. The citation reads:
2008
Marc Aaronson Memorial Lectureship
Awarded to
Dr. Michael E. Brown
California Institute of Technology
November 21, 2008
for his outstanding research and lasting contribution to astronomy through the characterization of the outer solar system and the discovery of objects comparable to Pluto
To which, they could have added, which all came about through a winding complicated path whose direction was never certain, but whose start was clear after being pointed out by Aaronson.
I never met Marc Aaronson, but, based on his wife and daughter, who I met yesterday, I think I would have liked him. If I’d had a chance, I’d like to have said “thanks.”
Posted by Mike Brown on Saturday, November 22, 2008
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6 comments

Haumea

On December 28th, 2004, I discovered a Kuiper belt object brighter than anything anyone had ever seen before. Being only a few days after Christmas, I naturally nicknamed it Santa.
The discovery was bittersweet. I had made a bet with a friend 5 years earlier that someone – anyone! – would discover a new planet by January 1st, 2005. The deadline was in 3 days, but I knew that Santa didn’t count. We didn’t know exactly how to define “planet” back then, but we decided that something of a particular brightness would count. Santa was bright , but not quite bright enough. Three days later I had still not found anything bright enough to count, and I lost the bet.
But, still: Santa! How would I have known back in 2004 that Santa would be the single most interesting object ever discovered in the Kuiper belt? It has a moon – wait, no, two moons! It is oblong, sort of like a football (American style) that has been deflated and stepped on. And it rotates end over end every 4 hours, significantly faster than anything else large known anywhere in the solar system.
Large? Well, at least sort of large. The long axis is about the same size as Pluto or Eris or Makemake. Back when I thought that maybe the IAU was going to vote that anything the size of Pluto or larger was a planet I was going to argue that Santa was indeed a planet – as long as you looked at it at exactly the right angle (luckily, the IAU was much more sensible, so I did not have to make such a crazy argument).
Stranger still, Santa has the density of a rock. We think that most things out in the Kuiper belt are about equal portions of rock and of ice, but, apparently, this does not apply to not Santa. It’s only rock. Except that even that is not true. When we finally got a chance to look closely at its surface with the Keck telescope we realized that the surface is nothing but ice. Santa must have a structure like an M&M, except that instead of a thin layer of sugar surrounding chocolate, the thin outer shell is ice and the interior is rock. Don’t bite.
These characteristics already make Santa the strangest object in the Kuiper belt. Several years ago we came up with what thought was a good explanation. What if, eons ago, Santa was an even larger Kuiper belt object and it got smacked – in a glancing blow – by another Kuiper belt object? That would explain the fast spin. And the fast spin would be enough to explain the oblong shape; anything spinning that fast would be pulled into such a big stretch.
What’s more, the initially large Santa could have had a rocky interior and icy exterior, much like the Earth has an iron interior and a rocky interior. When the huge impact occurred, it could have cracked that outer icy mantle and ejected all of that ice into space. The two moons that circle Santa are pieces of that icy mantle.
This explanation was, we thought, pretty good. And then it got really good.
While looking across the Kuiper belt at many different objects, we realized that a small number of objects in the Kuiper belt look like tiny little chunks of ice. How strange. Even stranger, though, was that all of these chunks of ice were, relatively speaking, next-door neighbors of Santa. We had found the other chunks that had been removed from the mantle of Santa. The story was complete.
……………………………….
After we discovered Santa, we worked hard to get the first scientific paper ready to announce the discovery. In science there is always a tension between doing the careful work to make a complete announcement and doing an instant but incomplete announcement in order to make sure you don’t get scooped. We were as worried as anyone about being scooped, but we resisted the temptation for instant announcement. We felt that the science was too important.
On July 7th 2005, as I was putting the finishing touches on the scientific paper, in hopes of submitting it the next day, I had a minor delay. My daughter was born. I had somehow convinced myself that there was no way that she would be born for another week. I was certain that I had more time. But I had no more time, no more time at all. I forgot about Santa and the rest of the Kuiper belt and turned my obsession from it to her. The announcement about Santa would have to wait, I was too busy sending out announcements about Lilah, instead. What difference would a few months make, really?
…………………………………
The announcement did indeed wait, but only for 21 more days. On a late Thursday night, between changing diapers and filling bottles and descending ever more into sleep deprivation, I checked my email and saw the announcement of the discover of Santa myself. A previously unheard-of Spanish team had just discovered Santa a few days earlier. And they called it the tenth planet.
No no no no no no no no! I was horrified. My discovery had just been scooped by a group who decided not to wait to learn more. They didn’t know any of the information about Santa that we did, in particular that it has a satellite and from the orbit of the satellite you could tell that it was only 1/3 the size of Pluto, and that it was definitely not the tenth planet. Worse, a few months earlier, we had actually discovered something that was bigger than Pluto. This was going to cause nothing but confusion.
That night, on no sleep but much caffeine, I stayed up to finish the paper about Santa that I had put aside three weeks earlier. We would not get credit for discovery, which was painful enough, but at least we would quickly set the record straight about its size and importance. After I sent the paper off, I sent a quick email to congratulate the Spanish team on their discovery and I filled them in on everything that we knew so that they could answer questions from the press correctly. Finally I nodded off to sleep.
I woke to a nightmare. In the intervening hours it appeared that someone had used the knowledge that we had been tracking Santa to start looking into what else we had been doing. Someone had traced where we had been pointing our telescopes for the past months. We had been pointing them at the object that would one day be called Eris – the object bigger than Pluto, the real tenth planet! That morning, the astronomical coordinates of Eris were posted to a public web page with discussions about what might be there that we had been watching. It was clear to me that as soon as the sun went down that night, anyone with a moderately large amateur telescope could point up in the sky at those coordinates and, the next day, claim they had discovered the 10th planet.
After breakfast, I apologized to my wife; I would have to go in to work today for the first time in three weeks.
I called my wife later in the day to apologize again. I was going to have an international press conference that afternoon and would she mind bringing me some nicer clothes? And a razor, perhaps? And more coffee. Definitely more coffee. That evening, the world learned that there were 10 planets.
……………………………………
After more than three years, Santa received a formal name today. Santa is now, and forever, officially Haumea. From the official citation issued by the International Astronomical Union:
Haumea is the goddess of childbirth and fertility in Hawaiian mythology. Her many children sprang from different parts of her body. She takes many different forms and has experienced many different rebirths. As the goddess of the earth, she represents the element of stone.
The name was chosen by David Rabinowitz of Yale University, one of the co-discoverers of Santa (along with me and Chad Trujillo of Gemini Observatory in Hawaii). He chose the name because Haumea is closely associated with stone, and Santa (as we knew it at the time) appeared to be made of nothing but rock.
But the name is even better than that. Just like the Kuiper belt object Haumea is the central object in a cloud of Kuiper belt objects that are the pieces of it, the goddess Haumea is the mother of many other deities in Hawaiian mythology who are pieces pulled off of her body.
Two of these pieces are Hi’iaka, the patron goddess of the big island of Hawaii, who was born from the mouth of Haumea, and Namaka, a water spirit, who was born from the body of Haumea. These names were chosen for the brighter outer moon and the fainter inner moon, respectively.
Officially:
Haumea I, Hi'iaka, discovered 2005 Jan 26 by M.E. Brown, A.H. Bouchez, and the Keck Observatory Adaptive Optics team

Hi'iaka was born from the mouth of Haumea and carried by her sister Pele in egg form from their distant home to Hawaii. She danced the first Hula on the shores of Puna and is the patron goddess of the island of Hawaii and of hula dancers.

Haumea II, Namaka, discovered 2005 Nov 7 by M.E. Brown, A.H. Bouchez, and the Keck Observatory Adaptive Optics teams

Namaka is a water spirit in Hawaiian mythology. She was born from the body of Haumea and is the sister of Pele. When Pele sends her burning lava into the sea, Namaka cools the lava to become new land.
But wait! Shouldn’t the official discoverer get to name the object? What of the Spanish team?
Yes. The discoverer should.
Several weeks after the Spanish team announced the discovery of Santa which precipitated the announcement of the object that would eventually be named Eris, which precipitated the entire discussion of dwarf planets, it became clear that the Spanish team had not been forthcoming. They themselves had been the first to access the web sites which told where our telescopes looked. And they did this access two days before they claimed discover (you can see a detailed timeline reconstructed from the web logs here)
Did they use this information to claim the discovery for themselves?
As a scientist, my job is to examine the evidence and come up with the most plausible story. Here are some possibilities. It is impossible to disprove this story, claimed by the Spanish team: while looking through two-year-old data, they discovered Santa legitimately, and then, only hours later, accessed information about where our telescopes had been looking and were shocked (shocked!) to realize that the object they had just found was the same object that we had been tracking for months. Wanting to establish priority, they quickly announced, knowing essentially nothing about the object.
Though this story cannot be disproved, it does not have much of an air of plausibility about it. Data that were two years old happened to get analyzed just hours before – whoops! – the team found out that someone else had found the same thing? Hmmmmm. Perhaps most damning, you would think that perhaps the Spanish team would be willing to admit this early on. Instead they appeared to attempt to hide the fact that they ever knew anything about our telescope pointings.
Let’s try a more plausible explanation: the Spanish team found our telescope pointings, used that information to infer the existence of Santa, and assumed that no one would ever know they had not found it legitimately.
No way to prove it, but the later hypothesis certainly sounds more plausible. To be fair, though, I don’t think there is any way to ever know the full extent of the truth, except on the off chance that someone on the Spanish team eventually spills the beans about what really happened. I keep waiting, but I don’t hold my breath.
But wait, there’s more to ask! If the telescope pointings were – even if inadvertently – on a publicly accessible web site, was it wrong to look at them? The obvious answer is that there is nothing wrong with looking at information on any publicly accessible web site, just as there is nothing wrong with looking at books in a library. But the standards of scientific ethics are also clear: any information used from another source must be acknowledged and cited. One is not allowed to go to a library, find out about a discovery in a book, and then claim that discovery as your own with no mention of having read it in a book. One is not even allowed to first make a discovery and then go to the library and realize that someone else independently made the same discovery and then not acknowledge what you learned in the library. Such actions would be considered scientifically dishonesty.
In the end, while we are likely to never know exactly what happened, it appears clear that the Spanish team was either dishonest or fraudulent. They have claimed the facts that merely make them dishonest. If I had to bet, though, I would bet for the later.
…………………………………………….
Officially, the naming of Haumea does nothing to put to rest this three-year-old controversy. The committee that voted to accept the name has said that, while they will take the name proposed by our team rather than the name proposed by the Spanish team, they are not favoring one claim over the other. They will let posterity decide.
OK, posterity, have at it. If I am no longer around to hear the news on the decision, that’s ok, you can tell my daughter Lilah instead. She will have been waiting, nearly precisely, her entire life.
Posted by Mike Brown on Wednesday, September 17, 2008
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60 comments

The Joys of Rejection and Lake-effect clouds on Titan


Remember my new paper that describes my interesting discoveries about Titan (see Your Saturday Newspaper)? submitted it to Science magazine a few weeks ago in the hopes that it will be published and some day make it to your Saturday newspaper. But it won't. It has been rejected.
It was a kind rejection. They didn't say "we think you're paper is wrong." Just, "we don't find it of general enough interest to publish in our journal."
Rejection is always hard. My first response was generic sputtering “wha.. wha… what?” and then disbelief “this can’t be!” and anger and dismissal “those idiots don’t even know what they are missing.” This sequence lasted about 7 seconds, and then I got over it. After about 1 minute I became excited.
Why be excited about rejection from Science? Along with the publicity benefits of publishing a paper in somewhere like Science comes the hard part. You agree not to publicize or discuss the paper before the publish it. This process can take 6 months or longer.
But having been rejected from Science, I quickly turned around and submitted the paper to a more specialized journal -- Geophysical Research Letters (aka GRL) -- which has no such restrictions, and then I went a step further and submitted it to an on-line electronic archive ( which means you can go read it right now! http://lanl.arxiv.org/abs/0809.1841 ).
Scientists these days are increasingly speeding up the slow process of formal publication with an informal process of web publication. Such web publication has good and bad aspects to it. Good: instant. Bad: unreviewed.
Anything that is published in a major journal has had one or two experts read it closely and suggest changes. My paper on Titan is currently undergoing this process at GRL, and, when the reviewers are done, I will modify and respond. But my paper is on the electronic archive for everyone to see before that even happens.
Posting a paper on-line before it has been reviewed can lead to great embarrassment. What if the paper has fundamental flaws and needs to be withdrawn or rejected? What if the referees point out places where major changes need to take part? All of this is certainly possible, and should make any on-line submitted wary. But, for me, the benefits outweigh the risks. I am sufficiently confident in the accuracy of what I did that I am not worried about any of these major problems. While there is no doubt that the reviewers will suggest some improvements, I don’t believe the overall conclusions of the paper will change significantly. And I think the conclusions are sufficiently interesting that I relish the idea that people will begin to read the paper and think about the results now, rather than 6 months from now. So I submitted.
And now, even better, I can talk about the discovery of lake-effect clouds on Titan.
Earlier this summer, while looking through NASA’s on-line archives of images of Saturn’s satellite Titan taken from the Cassini mission, I began to notice a recurring pattern up near the north pole of the satellite. The north pole of Titan has been in the darkness throughout a long long winter (a full year on Titan takes 30 years; winter is almost a decade) and is just now emerging into some spring time daylight. As it began to emerge, I noticed what appeared to be tiny little clouds popping up and disappearing right over the pole.
Titan is in some ways bizarre and exotic yet in some ways very earth-like. Both earth and Titan have mostly-nitrogen atmospheres; on both the surface pressure is about the same (the big difference on Titan: it lacks that minor contaminant – oxygen – that makes the earth a more interesting place….).
Titan and earth are the only bodies in the solar system known to have large expanses of liquid at the surface. On Titan, though, the temperature is so low that water is frozen solid. The lakes of Titan are made, instead, of methane and ethane. If you could figure out a way to get a pipeline there, Titan’s lakes could supply all of our needed natural gas for years to come.
On earth the liquid water is globally distributed. On Titan it appears that the liquid methane and ethane is confined to the poles.
Finally, Titan and earth both have clouds in its atmosphere, and these clouds are made from the dominant liquid on the surface. On earth: water. On Titan: methane.
Now, back to the little clouds I had seen popping up at the north pole during Titan’s early spring.
These clouds surprised me; they appear to be cumulous clouds – like large thunder heads. On the earth we only get such clouds in hot, humid places. Arizona in August. Year-round in the tropics. Temperate latitudes during summer storms. How could such clouds possibly be up at the north pole just as winter is waning?
It occurred to me that we do get winter cumulus-type clouds on the earth in at least one case: lake-effect clouds and storms. Lake-effect storms on the earth are those winter storms that blow across the Great Lakes, pick up moisture, and then proceed to dump many many feet of snow on places like Buffalo, New York.
The effect occurs in many other places around the world. Or, I should say, they same effect occurs in many other places around the solar system. I believe this process is precisely what is causing the sporadic clouds at the north pole of Titan.
Like everything else, Titan and earth have similarities and differences in their lake-effect clouds, too. On the earth, the formation of these clouds is greatly aided by the fact that deep lakes stay relative warm over the winter. So as cold air passes over these lakes the air both picks up humidity and a little heat. This heat causes the air to rise (like a hot air balloon) which, in turn, causes those cumuli and the subsequent snow.
On Titan, a decade of polar winter means that none of the lakes retain any heat, so passing air only picks up humidity (methane humidity, in this case). Something else needs to help push the air higher to cause those cumuli. In the paper, we speculate that there might be mountains at the north pole that help, but really that is just a wild guess.
Cold lakes won’t evaporate, so these clouds have only started to become active in the last few years as sunlight has started to every-so-slightly heat the lakes. Every time the lakes warm up just a bit, a huge dollop of evaporation occurs, which re-cools the lake, and we see a cumulus cloud pop up. The lake then has to wait for some more sunlight before it happens again.
If our general story is correct – and I think it is – then as spring and then summer approaches at the north pole, the sunlight will increase dramatically, and the lake-effect clouds will start to go crazy. And we’ll be watching. The Cassini spacecraft is slated to continue flying past and taking pictures of Titan for several more years. And we might find more exciting things.
And what will we do when we find exciting things? Well, in the end I will probably never learn my lesson. We’ll submit them to Science. Or we’ll submit them to Nature. And then we will have to wait for months to talk about them. And maybe they will get a paragraph in your Saturday paper. But, if we – and you – are lucky, we will instead be rejected, we’ll post to a freely available on-line archive, and everyone can hear early about the latest happenings on this bizarre satellite.
Posted by Mike Brown on Saturday, September 13, 2008
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3 comments

Your Saturday Newspaper

I don’t know about other newspapers, but every week my local -- the Los Angeles Times -- devotes about a half a page to a few science stories. I love these, not just for learning a little bit about the universe around us, but also for getting a quick glimpse into the life of some scientist somewhere finally getting his or her paragraph of fame. This week: estrogen may ease psychosis; mummified fetuses from King Tut’s tomb are going to have their DNA tested, a hidden tribe of gorillas was found, virus can get sick from other viruses, and Antarctica used to have moss. Having a paragraph or two of your science appearing in your daily newspaper is both exciting – “my research is interesting to the world” – and depressing – “I spent two years on this project and all that makes the newspaper is that schizophrenic women should take estrogen.”
The route from doing research to that Saturday paragraph is indeed a long one, and one of the important steps after the research is all completed is publication of the results in the right scientific journal. Scientific journals are not all the same. Some are trade journals that specialize in a specific field (I publish much of my research in, not surprisingly, “The Astronomical Journal”) and accept most of the papers submitted to them (after a sometimes lengthy review and revision process). Others are more general with the implicit promise that the papers published there are more interesting, more important, and will get more notice. And, of course, it is much harder to get a paper published in one of these. Reporters know which journals are those top exclusive general ones, and so, when looking for stories for that Saturday column, they peruse those journals (and read press releases, presumably) and never bother with the trade journals.
The two top general journals in which everyone seems to want to get papers published are Nature and Science. If you start looking at those Saturday columns you will be amazed by how many of the stories come from papers published there.
Interestingly, though, along with publishing important ground-breaking papers appears to come the requirement that a larger than usual fraction of the conclusions published in these journals turn out to be incorrect. This leads to the semi-joking line that you often hear amongst astronomers: “Just because it is published in Nature doesn’t necessarily mean that it is wrong.” But it also leads to the real ambivalence that some feel for results published in those journals. People sometimes consider them to be flash and hype with no real substance and turn their noses up at the papers published inside.
I’ve been known to fall into this camp myself.
So it might be amusing to know that, tomorrow, my hope is to have a new paper ready for submission to Science. Why would I do this when I then turn around and scoff at others? Hypocrisy, I think is the answer. Or, as my friend Caltech oceanographer Jess Adkins likes to say: Nature and Science are the People Magazine of science. And like People, no one wants to admit to reading it, but everyone wants to be in it.
And so I submit.
The process is an interesting one. By tomorrow, I should have the full manuscript describing all of the results and with a few figures demonstrating important points and a slew of references to previous work all written in the precise format demanded by Science. I’ll log on to their web site and do all of the submission there. And then I’ll wait.
I think the rest of the process goes something like this (I may have some of the precise details mixed up here, but you’ll get the general idea). The paper will first go to an editor in the field of astronomy/planetary science who will decide whether or not there is even a chance that the results are interesting enough to warrant publication in Science. If the editor doesn’t think so, I will get a rejection notice within days. If the editor likes it, the paper will go to an editorial staff meeting with all of the other editors where it can again be voted up or voted down. I can again get that rejection notice (this one would be in, perhaps, two weeks).
If the editorial board likes it, the editor will send it out for peer review. The manuscript will get mailed to (typically) two experts in the field who will offer their detailed advice on the technical merits of the paper and whether or not it warrants publication in Science.
As is often said: peer review is a highly flawed system, but it beats all of the alternatives. It is easy to imagine some of the problems that could arise at this stage. A few that I have run across: reviewers who are competitor, reviewers who just don’t like you, reviewers who aren’t knowledgeable enough about your field. With only two reviewers for most manuscript, the process can be thoroughly random. The same paper sent to twenty different reviewers would get twenty different reviews. But, sadly, it beats all of the alternatives.
With luck, the two reviewers will like the paper and, with even more luck, suggest ways to improve the paper. They may point in flaws in the paper and how those flaws can be fixed. Or they may point in flaws in the paper and say they are not fixable.
If the reviewers don’t like the paper sufficiently that is the end of the line and you are rejected. If they potentially like it but with reservations you are given a chance to respond to their suggestions or complaints and modify the paper accordingly and then they get to review it again.
Finally, again, with luck, the editor send you that email saying the paper is accepted, and you sigh from relief. Or you get the rejection email, and you decide what to do next: another general journal? Reformat to go to a trade journal? Sulk in irritation for a while? I have done all of these and more.
The whole process can take a long time. If I submit the paper tomorrow, there is a chance that it might appear in your newspaper in, perhaps, January. Keep your eyes peeled to that Saturday section. But don’t look for an article on dwarf planets or on the Kuiper belt or on the early solar system. I’m taking a break from those this summer to pursue research on what I think of as my hobby field, Titan. Titan is a fascinating world with methane lakes at the north pole, dark dunes at the equator, a thick atmosphere that is almost like the Earth’s (it’s just missing a minor component [oxygen] that we like so much), and a Los Angeles-like haze that makes the surface hard to see. It’s my favorite body inside the Kuiper belt, and, when I get a little tired of studying the little points of light that make up the Kuiper belt, I move in to the relative warmth of the Saturn system and see what’s new on Titan. During my break this summer I think I discovered something pretty interesting. Interesting enough to be published in Science, even. But we’ll all have to wait to see if I can navigate that laborious publication paper and make it to that one paragraph in your Saturday newspaper.
Posted by Mike Brown on Sunday, August 10, 2008
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A new window on astronomers

One of the goals of this column is to make it more clear what astronomers actually do all day (or night) long. As I have been discussing, one of the things that I do frequently is writing proposals to convince other astronomers to let me use their telescope. The once-a-year proposals for use of the Hubble Space Telescope were due on Friday at 5pm (I pressed the “send” button at 4:49pm). Here is the proposal that I submitted. While it is written for other astronomers, so often flies into astronomical shorthand, I think it is at least moderately readable by anyone generally interested in what is going on in the outer part of the solar system. Plus, there is no chance I could possibly attempt to write anything else this week. In that spirit, here is:

A compositional-dynamical survey of the Kuiper belt: a new window on the formation of the outer solar system.

The eight planets overwhelmingly dominate the solar system by mass, but their small numbers, coupled with their stochastic pasts, make it impossible to construct a unique formation history from the dynamical or compositional characteristics of them alone. In contrast, the huge numbers of small bodies scattered throughout and even beyond the planets, while insignificant by mass, provide an almost unlimited number of probes of the statistical conditions, history, and interactions in the solar system. Studies of these small bodies have been exploited for many years in the inner part of the solar system, where combined dynamical and compositional observations of asteroids have been used to trace chemical gradients, study early radioactivity, and detect and analyze collisional histories in the region of the terrestrial planets (Bottke et al. 2005 and references therein). While a similar study of the Kuiper belt would offer similar promise for understanding the formation of the region of the giant planets, the typical objects in the Kuiper belt are 10,000 times fainter than those in the asteroid belt, so this promise has been hampered by the difficulty of obtaining concrete observations of the surface compositions of these objects.

Instead, attempts to understand the formation and evolution of the Kuiper belt have largely been dynamical simulations where a hypothesized starting condition is evolved under the gravitational influence of the early giant planets and an attempt is made to reproduce the current observed populations(Levison and Morbidelli 2003, Tsiganis et al. 2005, Charnoz and Morbidelli 2007, Lykawka and Mukai 2008). With little compositional information known for the real Kuiper belt, the test particles in the simulation are free to have any formation location and history as long as they end at the correct point. Allowing compositional information to guide and constrain these studies would add an entire new dimension to our understanding of the formation and evolution of the outer solar system.

New visible-infrared capabilities of WFC3 allow such compositional information of a large number of Kuiper belt objects to be obtained for the first time. Here we propose to exploit these capabilities to perform the first ever large-scale dynamical-compositional study of Kuiper belt objects (KBOs) and their progeny to study the chemical, dynamical, and collisional history of the region of the giant planets.

Kuiper belt compositions: the current view.
Combining compositional and dynamical information on small bodies has proved a powerful technique in the inner solar system for understanding the formation of the terrestrial planetary region, but it has only been used to a very limited extent in the outer solar system. Color diversity.The earliest attempts to jointly consider outer solar system compositions and dynamics simultaneously were attempted using only the colors of KBOs.While colors are a poor proxy for composition, they have proved a fascinating early tracer of the dynamical homogeneity -- and lack thereof -- of the Kuiper belt. The earliest photometric observations (Jewitt and Luu 1998) suggested that KBOs came in a wide variety of colors and that there was no relationship between the color and any orbital or physical parameter of the object. To date, this great heterogeneity remains unexplained, though it clearly points to a wide diversity of formation or evolutionary histories throughout the Kuiper belt.

The cold classical KBOs.
Subsequent observations of colors of larger numbers of KBOs eventually showed that one dynamical subset of the Kuiper belt, the ``cold classical KBOs'' on dynamically cold low inclination and eccentricity orbits, consists exclusively of objects that are red (Tegler and Romanishin 2000, Trujillo and Brown 2002). While the color red is impossible to interpret compositionally without more spectral information, the existence of this red grouping has been used to argue that the cold classicals are a unique population whose dynamical coherence has been maintained through the dramatic evolution of the outer solar system (Morbidelli and Brown 2004). The need to retain this group of objects is one of the key constraints on -- and sometimes the death of -- models of the evolution of the outer solar system and is the earliest example of the power of combining (even limited) compositional information with small body dynamics.

While color groupings have proved interesting for helping to understanding the evolution and rearrangement of the outer solar system, the actual cause for the different colors remains unknown.Infrared spectroscopy would allow a direct probe of the surface ices common in the outer solar system, but for many years few infrared spectra were available, as few KBOs were bright enough for even the lowest resolution spectroscopy with the largest telescopes. This difficulty was partially alleviated by our wide field search for the largest KBOs (Brown 2008), which finally provided a moderate number of bright observable objects, and by long term programs at VLT and Keck that slowly obtained spectra of the very brightest of these (i.e. Barucci et al. 2006, Barkume et al. 2008). The most systematic survey to date is our Keck survey (Barkume et al. 2008), which obtained 1.5 to 2.5 micron spectra of 45 objects in the outer solar system. Three results from this small sample provide examples and details of what could be expected from a much larger survey.

Fragments from a giant primordial collision.
One small set of KBOs stood out in the Keck survey for their unique spectra (Fig 1a). This collection of objects has surfaces which look like laboratory spectra of pure uncontaminated water ice. Moreover, all of these pure water ice objects have nearly identical orbits(Fig. 2a), and the largest of them, the nearly Pluto-sized 2003 EL61, had previously been speculated to have suffered a giant impact at some point in its past which gave it its rapid spin and system of at least two moons (Brown et al. 2006). The compositional and dynamical association of the water ice objects with 2003 EL61 itself made it clear that the small set of pure water ice objects were fragments of the giant impact that had shaped 2003 EL61 (Brown et al. 2007). This impact is the largest anywhere in the solar system for which we have multiple extant fragments identified, providing a unique laboratory into the types of massive collisions which shaped the solar system.

It is expected that the 2003 EL61 impact occurred during the time of solar system clearing when the Kuiper belt was significantly more dense than its current state. A model by Levison et al. (2008) suggests that the impact actually occurred between two objects which were themselves in the processes of being scattered out of the solar system. As would be expected from a collision of objects that were on unstable orbits, some of the 2003 EL61 family is itself in an unstable region of space. In Ragozzine and Brown (2007), we exploited these instabilities to develop a dynamical chronometer to use the current spread in orbital elements of 2003 EL61 fragments to determine the time of the 2003 EL61 impact. To date, with the small number of family members known, we can only place a lower limit of 1 Gyr on the age. But with more objects discovered we will be able to more precisely date this impact, and thus date the time of solar system clearing.While almost all models to date assume that major clearing occurred 4.5 Gyr ago, the new and to date quite successful Nice model (Tsiganis et al. 2005 and papers following) posits that solar system clearing was delayed by ~1 Gyr and did not largely occur until the time of the Late Heavy Bombardment. The study of the dynamics of this compositionally unique set of objects could answer one of the most important questions about the timing of major events in the outer solar system.

The methane giants.
Schaller and Brown (2007) suggested that a small number of the largest and coldest objects should have enough surface gravity to maintain their volatiles against loss to space over the age of the solar system. In their model, the final loss to space is controlled by the slow leakage of Jeans escape from a vapor-pressure controlled atmosphere. The loss is an intimate function of the object size and of the precise orbit. The results of the model predictions to date have been nearly perfect: almost everything that the model suggests should have volatiles on the surface (predominantly methane; Fig 1a) does, and nothing that the model suggests shouldn't have volatiles has been found to have volatiles. This success opens the possibility of being able to find outliers with unusual dynamical or compositional histories by finding objects whose predictions don't fit within the framework of the model. Indeed, the one object which doesn't fit the model prediction is 2003 EL61, the giant parent of the collisional family. We presume that the impact took away most of the volatiles on the outermost fragments, but, more importantly, even if we had know nothing else about 2003 EL61, its failure to have a predictable surface composition would have quickly drawn attention to it.

Overall spectral diversity.
 Once the 2003 EL61 family is removed from the spectral sample, no apparent compositional-dynamical correlation or pattern is seen in the remaining 40 objects (Fig 2a). While the compositions of asteroids are strongly stratified as a function of heliocentric distance, the KBOs have no such stratification. Just as objects with different optical colors are jumbled throughout the Kuiper belt, so are objects with different infrared spectra. Unlike the asteroid belt, however, where compositional differences are glaring and distinct, in the Kuiper belt, the spectra of almost every KBO fits along a smooth continuum with the only differences being the amount of absorption due to water ice and the optical color (Fig 1b). While initially unexpected, the lack of other significant surface ices is now understood as a natural consequence of thermal escape of the more volatile ices (Schaller and Brown 2007).

Oddly, however, little correlation appears between the optical colors and the amount of water ice absorption (Fig 1b), conflicting with the commonly held conceptual view that KBO surfaces are a simple mix between red colors due to irradiated organics and blue colors due to fresh water ice exposed by collision (Jewitt and Luu 1998) or that KBOs can be compositionally classified by optical colors alone (Barruci et al. 2006).

While the cause of this continuous diversity is unknown, the broad possibilities are limited: the surfaces can reflect either primordial differences in the objects, subsequent evolution of the objects, or both. Primordial differences would likely reflect formation location, while evolution could reflect both thermal and collisional history.

Whatever the cause of the surface composition variability, understanding the reason would allow significant new insights into the evolution of the outer solar system. If the variations are primarily primordial, we could use KBO composition to reconstruct the initial locations of the objects that are now jumbled in the Kuiper belt, while if the variations are evolutionary we will be able to use compositions to reconstruct collisional or thermal histories of different regions of the Kuiper belt. In either case, with the current small number of objects known it is impossible to determine the cause of the variability, but the promise for this potential tool is strong.

The proposal continues on for another few pages, describing precisely how we want to use the Hubble Space Telescope to answer some of these questions that we had set out here.
Posted by Mike Brown on Sunday, March 09, 2008
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4 comments

Procrastination season

On occasion, my day job is going to interfere with finding the time to write these columns. For an astronomer, there are things like Jupiter season and the seasons of the moon, but there is also proposal season. And proposal season starts now.
For almost every telescope that I ever use I have to write a proposal convincing another group of astronomers that the project that I have in mind is worthy. Depending on the telescope involved and precisely when you want to use that telescope, the competition to be one of the people selected ranges from moderate to extreme. The proposal that is current occupying my time is one to use the Hubble Space Telescope. Even after 16 years in space, the Hubble is still one of the most sought after telescopes around. One of the reasons it continues to be so good is that every few years the Space Shuttle goes to the Hubble, fixes anything that may have broken, and installs newer more modern cameras. The last of these Shuttle refurbishments is slated to take place this summer, and afterward the Hubble will be equipped with the last ultimate cameras to scan the cosmos.
I am salivating to use these new cameras, and so are most of the other astronomers around. Who gets to use them and who doesn't will all be decided on the basis of proposals being written right now. Only about one in five will have a proposal accepted. I want to be one of them.
How to do it? How do you write a proposal that will be accepted? It's probably not unlike many other businesses. You need two key things: a great idea and a great sales pitch. Scientists often forget about the sales pitch part. After all, a strong scientific idea should be able to stand on its own, right? No chance. I have seen proposals with solid scientific ideas presented poorly, and they rarely even get looked at twice. Occasionally I've seen it the other way around: great sales pitch for a mediocre idea. To their credit, I think that scientists rarely fall for that, either. You really need both.
For the proposal I am currently working on I think I have a great idea to work with. I hope to do a large scale survey to understand the different types of objects in the region of space beyond Neptune. The proposal nicely builds on years of preliminary work we've done with telescopes here on earth, and it uses the Hubble study many more of these objects which are too faint to see from the earth.
It's a good scientific project. There are things that we know we will find, but there is also much room for unanticipated discovery.
But it's going to need a good sales pitch. Just like in every other profession, there are specialities that are trendy and those that are not. In astronomy, distant galaxies and supernovae and the earliest phases of the universe are trendy. Our solar system -- even the distant edge of our solar system -- is decidedly not. It's too small; it's too close; it's too specific. Why worry about the details of what happened in one insignificant corner of one insignificant galaxy when instead you could be studying the formation of the universe itself? I think there are good answers to this question. I think that without studying the details we will never know if our more general ideas are correct. And I think that the significance of our corner of the galaxy is vastly increased by the fact that is our corner.
But will I be able to sell it? I cannot predict, but decision will be announced on June 15th. Stay tuned. In the meantime, do not be surprised if proposal season takes its toll on these pages. But don't give up all hope. As can be seen even right now, writing these pages fullfills one important need without which no proposal could ever be completed: procrastination.
Posted by Mike Brown on Saturday, February 23, 2008
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Science? You betcha.

I’d been thinking a lot about bets recently.
One evening a while back I was working late in my office on the Caltech campus, and I decided to take a break by dropping into a lecture by a Caltech economist (why not? I didn’t know anything about economics. No better time to learn) who had described experiments they had been performing demonstrating the efficiency of markets at collecting, analyzing, and making decisions based on diffusive knowledge. The specific example that still sticks in my head more than a decade after I heard this single lecture was the real-life case of a computer manufacturer trying to predict next month’s price of computers and printers. Several people in the company were supposed to be experts at these predictions, but they rarely got the right answer. The experiment that the Caltech economist ran involved letting everyone at the company who had any sort of knowledge about any part of the process participate in a predictive market, where they could buy “shares” in a certain price point, or essentially bet on what the price next month was going to be. If they were wrong, all of the shares that they bought were worthless, but if they were right they could win big. This was simple betting, but with a twist. The market price of the “shares” somehow reflected all of individual thoughts and hopes and speculations of what the price would be. No one thought that a computer was going to cost twenty dollars, so you could buy shares of “twenty dollars” for next to nothing. Of course, they were pretty much guaranteed to be worth absolutely nothing, which is less than next to nothing, so you would lose money. As you got closer to the price that most people thought the computers were going to be next month the cost of the shares rose.
All of this experimentation could be considered an interesting exercise except for one astounding point: the economists found that the market was better at forecasting the future price than the “experts” were. Somehow all of the individuals were able to exchange and synthesize information simply by buying and selling shares of prices and all of this information exchange led to better predictions than anyone else was able to make.
As I sat and listened to this that evening at Caltech I was shocked and astounded and excited. Scientists had always thought they had a monopoly on the best way to predict things (“the scientific method”) and yet here was a totally non-scientific method that seemed to lead to truth in a pretty clear way. It was a strange truth: not one proved with postulates and experiments, but one simply deemed the most likely.
Before getting too carried away with these ideas, though, I also learned at that lecture that markets aren’t perfect predictors and that the economists could run similar experiments where, with a few simple tweaks, they could make market bubbles and other odd effects. This fact would come as no surprise to anyone who has read a newspaper in the last few months.
I walked back to my office that night with my head trying to reconcile science and markets. OK, so perhaps this market approach couldn’t lead to truth in quite the way that the scientific method could, but maybe there was still a place for it. What about scientific markets for things that can’t quite be proven beyond sufficient doubt but that most scientists would be willing to bet a lot on. The first thing that came to mind was climate change. To most earth scientists, the only arguments about climate change are precisely how strong an affect it will be in different places. But somehow, because of the complexities of the questions, the public frequently sees the disagreement over the uncertainties rather than the fundamental agreements. Clearly, this was a place where a market could work. What about betting on the magnitude of climate change? Buying shares of the average temperature rise by 2050?
While this was all fun speculation, it also seemed obvious that given that the people were confused by the science, they were just as likely to be confused by scientists buying shares in a future temperature market. Clearly this was interesting, but going nowhere. But what about just using the ideas amongst scientists? If I could get all of the astronomers around to buy into a market on whether or not earthlike planets would ever been found around other stars, for example, I would have an effective way of collecting all of the disparate information that everyone had and coming up with the best prediction based on all of the data.
But then I realized that the idea could be taken one step further. Scientists could engage in what amounts to insider trading in markets! If I really believed, for example, that the climate was warming, and that, for the most part, the rest of the world was not dealing rationally with that fact, I should buy land somewhere in central Canada where it is right now too cold for most people and then I should reap the incredible returns when the land prices skyrocket because people can no longer live in Los Angeles anymore (as crazy as this sounds, I know one scientists who independently came to the same conclusion and bought himself some [currently] chilly property in Minnesota). A market does exist for climate change speculation, only it is a bit more indirect than simply betting on temperatures.
As a mere professor, I don’t have the financial means to follow up on my late night thoughts, but the ideas still continue to percolate in my head. I remain convinced there must be a way to figure out something about which you were certain but which was not generally understood and then use that knowledge to hit it big.
It is a testament to my general lack of financial thoughtfulness that after all of this interesting speculation and pondering about bets and markets and scientific insider trading that the best I ever came up with for my own personal attempt to hit it big with a piece of scientific speculation was a bet made in 2000 that someone would find a tenth planet before January 1st, 2005, with the winner of the bet to receive five bottles of champagne. Perhaps it is also a testament to my happiness at drinking champagne.
I think, though, my five-bottle-of-champagne market tells you that scientific markets, in the end, won’t work. I think that the best scientists are more motivated by being the one to discover and prove the truth than by being the one to guess correctly at the truth and profit off of it. Even though I am exceedingly certain that the world will be warmer fifty years from now I would still rather figure out a way to demonstrate the fact convincingly (or better: prevent it) than go buy Canadian land. And for those years between 2000 and 2005, when no tenth planet was in sight, I was not busy considering the financial plight of the loss of five bottles of champagne, but rather I was searching the sky, night after night, in the hope that when the champagne was drunk, it would be drunk in honor of the new planet I had found.
Posted by Mike Brown on Saturday, February 09, 2008
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I ♥ Astrologers

Please don’t tell any of my fellow astronomers, but I love astrologers. Really I do.
Don’t get me wrong. I have absolutely no belief whatsoever in the proposition that the positions of planets or stars or moons or anything else that is moving across the sky has or ever has had any sort of control over your life, your actions, or your choices. Zero. Really.
So if I don’t believe in what I must assume would have to be considered a central precept of astrology, how can I possibly claim to love the practitioners? Let me count the ways.
Astrologers care about the sky and the positions of the stars and the moon. I care about the sky and the positions of the stars and the moon. Astrologers try to understand patterns in the orbits and motions of the planets and determine their meaning. I try to understand patterns in the orbits and motions of the planets and determine their meaning. In a broad sense, we do many of the same things; it’s just that our methods are different.
Astrology and astronomy are brothers with roots deeper than just the first five letters. Until perhaps the Enlightenment they were inseparable. Copernicus, who made one of the greatest conceptual leaps in human history, pulling the earth out of the center of the universe and replacing it with the sun, was a dedicated astrologer, calculating astrological charts with as much fervor as trying to understand the paths of the planets. It’s not hard to understand why he would feel that some connection should be there. I don’ t think anyone can watch the rhythms and pulses of the movements of the planets and sun and moon and not somehow get a gut feeling that there is somehow meaning in all of that beauty, precision, and symmetry.
But from their common upbringing, the brothers split in adulthood. They each retained their common interest in the sky, but with thoroughly different ways of looking at it. Astronomy moved to the purely objective realm of descriptive and predictive reality. It moved to science. And a wondrous science it is. I can go outside tonight and look up to see the bright glowing star Betelgeuse, the red orb in the upper corner of constellation Orion, and then I can tell you a pretty good version of the entire story of its birth in a cloud a gas and dust, its long existence as a smaller and cooler star with hydrogen atoms fusing together in the deep interior, and its recent expansion to form ball of gas the size of the orbit of Mars. That we have been able to determine this story at all, simply from looking at the feeble light from these little points in the sky, is as improbable as it is incredible. When I see Betelgeuse at night and stop to think these thoughts I am left in awe.
So what can astrology offer that can even come close to matching? It can’t tell me anything, I don’t think, about my history or my future or my personality or my pitfalls. Or about anyone else’s. Isn’t it therefore worthless, or even potentially dangerous? I don’t think so. Astrology is the brother who kept the fascination with the sky but rather than growing an interest in science kept its interest in humanity. Scientific astronomy, for all of its awe-inspiring, mind expanding, and just simply amazing discoveries, leaves people and their consciousness out of the picture. Astronomy involves people looking up at the heavens, but the heavens are never looking back. Astrology, in contrast, never removed that connection between the sky and the people.
But but but, you protest, there is no connection between the sky and the people. The heavens do not, in fact, look back. And, while you are scientifically correct, you are culturally incorrect. You are thinking literally, but you need to think literarily. Good astrology can be like good literature. Good literature builds a world that is not the real world but teaches us more about ourselves than we would ever learn by simply staring in the mirror. No real King Lear ever had a trio of daughters to split his kingdom amongst nor wandered insane on the heath, but do we disdain Shakespeare for writing about it? No, we read, and we think about children and parents, we think about truth and loyalty, and scheming, and we learn more about ourselves and our world. We’re left enriched by stories that are not true.
Again, I have to plead: don’t get me wrong. I’m certainly not saying that all astrology is equivalent to Shakespeare, but neither is all of the rest of the fiction writing out there. The in-flight magazine that I currently have in front of me has both a short story and an astrology page. I would rate them equal quality examples of their genres.
Here’s a snippet of my in-flight horoscope (I’m a Gemini, perhaps explaining my ability to accept the dual nature of astronomy/astrology) for the month of January:
As your attention is consumed by an array of projects, you may spread yourself too thin. Remember to stop and take a breath, if for no other reason than to garner some perspective.
OK. I don’t need an astrologer to tell me that, but it’s hard not to read it and, why, yes, stop and take a breath and garner a little perspective. It’s not such a bad idea.
A quick perusal of the short story, a few pages earlier, gives a remarkably similar take home message, spread out, instead, over about three pages. After reading both of these I am now convinced: I think I will stop and garner some perspective, at least if I can finish a few of these other projects first.
So where are the Shakespeares of astrology? I will admit to not knowing if they exist at all. My astrological reading is only passive; occasionally someone will send me something and in a spare moment I will pick it up and I just might find it a bit intriguing. Here, for example, are some thoughts about Eris by Henry Seltzer, writing in The Mountain Astrologer:
The astrology of Eris seems to be related to the no-holds-barred fight for continued existence that is fundamental in all natural processes, and to taking a stand for what one believes, even if violence is involved. As the sister of Mars, the God of War, Eris willingly sought the battle. There is a side of nature that is quite harsh, a struggle for survival; this struggle is an essential part of the human condition as well, for we are still half animal. Nature can be viewed in a rosy light, as it was in the hippie era of the Sixties, Bambi innocently drinking from a little stream. But underlying this beauty is the possibility of sudden death at any moment, since all of nature's children need to eat. Eris is related to this principle of violence as a natural component of existence and to the concept of the female warrior that embodies it, especially the feminist struggle for rights in a patriarchal society.
As a general discussion of the national psyche circa late 2007 this passage is not at all bad. It covers the war in Iraq, global warming, and the Hilary Clinton candidacy all in the discussion of one name. It certainly does not require literal belief that the naming of an object in the sky is the actual cause of any of the things discussed.
But what is the point of astrology if you chose to read it figuratively rather than literally? Again, you could ask the same question of King Lear. You could ask the same question of the Bible. And you wouldn’t. To ask it is to miss the point entirely.
Here’s a question you should ask though: why tolerate the existence of astrology, with the danger that people might actually take it literally, with the danger that it might confuse and distort science, with the fear that real cause and effect will become confused, when real literature abounds? Why read pithy but relatively generic snippets of advice and pretend they are somehow connected to a particular constellation along the zodiac? Why read more extended essays purporting to be an in-depth analysis of how a recently discovered ball of rock and ice far from the earth affects all of humanity? The answer? There is no reason. I personally prefer my literature to be of higher quality, to make me think and feel more. Feel free to follow my lead. But if you do chose to read it, read it for the reason that I can’t help but love it. Astrology is not just figurative literature about humanity. Astrology cares about the sky. The astrologers who occasionally correspond with me love to hear about new solar system discoveries, figure out orbital relationships and patterns, and speculate about what else might be out there and how everything fits together. I do all of these things, too. I then take these thoughts and move on to think literally their scientific implications. The astrologers take these thoughts and move on to think figuratively about what these mean for humans. But we, astronomers and astrologers, start in the same spot, with an intense interest in the sky. To me, that matters.
Astronomy and astrology are brothers. Brothers don’t always do the same things or make the same choices. But when they maintain their initial ties to where they came from, their connection cannot help but stay strong. What is not to love?
Posted by Mike Brown on Saturday, January 26, 2008
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