Mike Brown's Planets: Lilah

Showing posts with label Lilah. Show all posts

Changing my world

After writing last week about a pretty major 5 year anniversary – the discovery on Dec 28^th 2004 of what is now called Haumea – it seems funny to be writing once again about a 5 year anniversary. But that’s just the way that reality worked. Eight days after discovering Haumea, and just a few days into the new year of 2005, I was back in my office again. I wanted to be studying Haumea – or Santa, as we called it then – since I was certain that it had to be bigger than Pluto, but, sadly for me, we still didn’t have any new data on it. We only had those first three pictures and there was nothing new to learn. We were scheduled to get more data soon, but not soon enough for sooth my anxiousness. My fingernails were nubs.

Continue reading full article >>

The end of the fall

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

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

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

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

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

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

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

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

But wait, there’s more!

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

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

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

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

Planetary Placemats

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

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

“But Daddy, where is my mat?”

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

“The planets!” Lilah exclaimed.

“Ugh” I thought.

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

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

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

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

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

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

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

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

I find this solution perfectly awful.

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

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

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

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

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

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

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

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

Homeward bound

I’m on my way home today from a quick trip a third of the way around the world to use a telescope.

Astronomers are, of necessity, vagabonds. Sometimes the thing that you want to look at in the sky is only viewable from the southern hemisphere, so down to Chile you go. Sometimes the thing is so faint that only the biggest telescopes around are worthwhile, so it’s off to Hawaii. What’s rare, though, is to spend 24 hours flying from Los Angeles all the way to the Canary Islands – a group of high volcanic crags off the coast of Africa with a latitude almost identical to that of southern California – to use a telescope smaller than the one that is just a three hour drive from my house.

When, after a day of travel, I got to La Palma, the island whose highest peak is strewn with telescopes, and I stepped outside into the dark dark night sky, I was greeted with exactly the same sky that I see in Los Angeles. OK, there were many many more stars, but they were all in their right places, and nothing was there that I couldn’t have seen from home.

So why spend all of that time to travel to a telescope smaller than my local one when all of the same sights were visible? Because when it was night time in the Canary Islands the sun was still high overhead in southern California. And the thing I was hoping to see only happened right then. If I had stayed home and waited eight hours to look later I would have seen nothing.

Here is what I hoped to see: that night the funny oblong fast spinning dwarf planet Haumea was passing directly in front of one of its satellites (Namaka is its name). If I could determine precisely when it happened and how long it lasted I could learn many things about Haumea (its size and crazy shape, maybe also its interior structure) and also about Namaka (how big it is, how much it is being tugged around by the other satellite, Hi’iaka). But all of this was happening so far away that the only way I could tell when Namaka disappeared behind Haumea was that the total amount of light coming from Haumea should dip by about 1%, So at the telescope I spent two entire nights doing nothing but staring at Haumea and measuring precisely how bright it was every two minutes. For comparison, I also checked a couple of stars nearby at the same time. If they stayed steady while Haumea dipped in brightness I would know I was in business.

It all sounds so simple.

In reality, though, stars never stay the same all night long. They get brighter as they get higher in the sky and fainter as they drop. Even on the clearest nights they fluctuate due to changing atmospheric conditions. Seeing this tiny drop in brightness of Haumea in the face of all of this intrinsic variability is a tough task.

But I tried.

After two nights at the telescope I am leaving with my laptop filled with pictures of the sky and my hopes high. Did we see it? Did we detect this tiny dip which told us that Namaka disappeared? I think so. I have a plane ride from London to Los Angeles tomorrow to look at the data more closely and convince myself what might or might not be there. But I think so.

If we didn’t detect anything it’s bad news. Perhaps our predictions are off, or it’s just too small of a blip for us to ever really see. But if we did detect it then our work is really just begun. Turning that little blip in the sky into concrete information about Haumea and Namaka will take a lot longer than tomorrow’s plane ride. There will be many more such trips around the world to be in precisely the right place when it happens again. There will be detailed computer models of the exact time and depth and duration of the blips. There will be confusion and ambiguity. But that is all in the future. For now I have the simple pleasure of long uninterrupted plane ride where I can stare and poke at the data, catch up on some reading, and think about these dwarf planets. And at the end I get to pick up my daughter from school and she’ll ask “Daddy daddy daddy did you see any stars?” and I’ll tell her that I did, but that the stars here at home are always the very best ones in the sky.

Baby Pictures

Last night, for the second time this decade, I got to have dinner and give a talk on the floor of the dome of the famous 200-inch Hale telescope at Palomar Observatory. It’s rare for anyone to give a talk on the floor of the 200-inch telescope, because Palomar, like every other large telescope around the planet, is used night after night after night looking at everything from the nearest asteroids to the edge of the universe. Few or no pauses are allowed for frivolities such as dinners and talks (in this case we got in, had dinner, gave a talk, and vacated the floor just as the sun was setting). So it was a treat when I got invited to speak to an intimate gathering of supporters of Palomar and Caltech – the university where I work and the one which, not incidentally, owns and operates Palomar – on the floor of the dome. It was even more of a treat because I had been the speaker at the last one of these dinner 8 ½ years ago, and it was particularly interesting to reminisce about what had happened in the almost-decade since then.

When I gave that first talk, in September of 2000, I was a young assistant professor at Caltech who had embarked on what I think it is fair to say was an audacious project: I was going to go find the 10^th planet. I had spent the previous two years systematically scanning a wide swath of sky using the seemingly ancient technology of manually slapping giant glass photographic plates to the back of a wide-field telescope, exposing the photographic plates to the sky for half an hour at a time, developing the photographic plates in the darkroom downstairs, and then looking at repeat exposures of the same patch of the sky to see if – perhaps! – I could find something that had moved. It was exactly what Clyde Tombaugh had done 70 years earlier that had led to the discovery of Pluto, but, no, I had the advantage of a much larger telescope and the use of computers to help analyze the final photographic plates.

At the time of the talk 8 ½ years ago I was in the third year of the project, where I was going back with a larger telescope to try to confirm anything that I thought I had detected during the first two years with the photographic survey. I told my audience sitting under the 200-inch telescope about what I was doing and about what I hoped to find. I told them about photographic technology versus the new digital cameras now widely in use. I told them about why I thought that after this third year I was going to have made that discovery I was hoping for and the 10^th planet would be in our grasp. It was, I daresay, a talk full of exciting promise.

It’s a good thing I wasn’t asked to give a follow up talk right away.

By the following year it was clear that my three year survey had found a grand total of absolutely nothing.

I told that story last night at the 200-inch telescope and everyone chuckled. They chuckled, of course, only because they knew what came in the years that followed. What came next? We scraped the photographic plates, installed experimental digital cameras, roboticized the telescope, and kept scanning and scanning and scanning. With the benefit of the faster and more sensitive digital cameras we slowly surveyed the whole northern sky and blew the outer solar system open.

Last night I showed my baby pictures from the past decade. I showed Quaoar, the first large Kuiper belt object that we found, the one named for the creation force of the local Tongva Native American tribe, the harbinger of larger objects to come. I showed Orcus with its newly named moon Vanth, and talked about its odd mirror-image orbit to Pluto. I showed Sedna, far beyond the Kuiper belt, in an orbit that takes 12,000 years to go around the sun, named for the frigid Inuit goddess of the sea, a beacon pulling us even further in the distant solar system. I showed Haumea, with her two moons Hi’iiaka and Namaka, spinning her was across the sky, I showed lonely Makemake, bird god of the Rapa Nui, the runt of the litter that produced the Big Three of Makemake, Pluto, and Eris. And then, of course, I showed Eris her, in all of her discord and strife, with her tiny moon Dysnomia circling her.

I really do feel like each one of these is like a child to me. And, like children, whenever the rest of them are not in the room, I will secretly tell you that this one is my favorite. They’re all my favorites. I can tell you stories about their little quirks, their odd habits, and a funny thing that this one did the other day when it thought no one was watching (did you know that the night before Namaka went right behind Haumea playing a little hide-and-seek with us? Silly little moon.).

Something else was particularly interesting to me about my talk 8 ½ years ago at Palomar. Something happened that day that I am certain I will never forget. I was inside the telescope waiting for the group of Caltech supporters to arrive, and finally hearing the knock on the outside door, I opened the door, and, as my eyes adjusted to the blinding outside light, I was greeted by the director of the group of Caltech supporters. She had worked on the Caltech campus for years, but somehow our paths had never crossed. I had certainly never seen her before. How do I know for sure -- you might ask. Trust me -- is my answer. I would have remembered. She walked in the door, and I fumbled my words introducing myself. Her name was Diane Binney.

Diane Binney doesn’t work at Caltech anymore, but she came on the trip to Palomar last night anyway. It was her first time back to the mountain since that time 8 ½ years ago when I gave a talk up there. She came to see old friends and revisit old places. And, since she hadn’t seen many of the people in a long time, she brought baby pictures of her own. She has a 3 ½ year old daughter named Lilah. Lilah has Diane’s last name as a middle name, but she gets the last name from her father. Me. Lilah Binney Brown.

We'll always have Regulus

I find Paris disorienting.

First, I missed an entire nighttime. When my wife and I arrived at the airport to embark on our vacation it was a southern California late afternoon. When we landed – first in Zurich – it was a Swiss early afternoon. Somehow I had missed an entire fast-forward cycle of the sun setting, the stars rising, and the sun rising again, all in the space of about 4 hours. When I first closed my window shade and then closed my eyes on the airplane – somewhere over Salt Lake City, I think – I made a mental note to be sure to try to open up and see the sunrise – over Greenland, I guessed. But even for the fitful sleep of a bumpy airline seat the sunrise came too quickly. When the thought to open my eyes and look out the window finally solidified sufficiently inside my head we were already over Ireland. I slid the window shade open a tiny crack to take a peak and the entire darkened airplane cabin was blasted with late morning glare. My wife, still attempting to sleep in the seat next to me, added her own glare to that of the sun and I quickly closed the shade. By the time we landed in Zurich and then finally continued on to Paris the sun was already on its way down again, but, still, I feel like a lost nighttime in there somewhere. Nights are precious things, and one should not lose them lightly.

If losing a nighttime were not disorienting enough, I believe that the streets of Paris are uniquely designed to make me lose my sense of direction. I pride myself, most of the time, with having a finely tuned sense of direction. I tend to be able to get from point A to point B by dead reckoning, no matter how many twists and turns and detours are along the way. So on the streets of Paris my general navigational strategy is to take a look at a map to see where we are and where we would like to be, and then I head off in what seems to be the correct general direction knowing that I will get to where I’m going. But the streets of Paris are tough. It’s not just that they aren’t oriented along a north/south axis. It’s not even that they aren’t oriented along any single axis. And it is not even that the streets sometimes curve. It’s that all three of these occur in small quantities. A street that I am on starts out general north-northwest, which, in my head, I probably think of as “northish” and then the street slowly, imperceptible turns west or even perhaps a little south. I then take a left turn onto a street which I think of as going westish when, in fact, it is more like the north-northwest direction I was originally headed. Do that a few times and there is no telling which way you are really going.

The first night we arrived, jetlagged and awake at midnight, I thought it would be fun to walk down to the Seine to see Notre Dame lit up at night. Point A: our hotel. Point B: Isle de la Cite. Direction: north-nothwest. After about 45 minutes of walking in the bitter bitter cold (ok, I live in southern California, so the fact that it was only a few degrees above freezing qualifies as freezing for me) we stumbled out of some small twisty city streets directly into the Pantheon, which was indeed spectacular all lit up after midnight. I’d never been to the Pantheon before and didn’t quite know where we were. I finally got out the map. We were a block from our hotel. Point A to Point A in just 45 near-freezing minutes. My wife gave me a similar glare to the one from earlier that morning.

Paris is a city to which my wife and I have both been a few times, but which we do not know well. We’re staying in a part of town which I have never visited. Our college French is rusty. An after flying for 12 hours and missing a full sunset and sunrise and finding myself unable to make it to one of the most obvious landmarks in town and struggling to remember the French phrase for, say, “Excuse me, madame, but do you know why I seem to keep walking in circles?” I feel very very far away from home in Pasadena. Looking at the globe you can see just how far it is, as I kept explaining to Lilah, our 3 ½ year old, who wanted to understand exactly where we were going to be (a place she calls “Parisfrance”) while she stayed home with her grandparents. “Parisfrance is really really far away Daddy. If I were on the airplane I would have to fall asleep.” A wise girl, I think.

But then, still trying to straighten out my post-midnight rambling route, we hit a slight opening to the sky and the clouds clear a bit and there, a bit low in the sky in about the direction we’re heading is a bright star and a little backwards question mark of fainter stars. The constellation is unmistakably Leo. The star is Regulus.

“Let’s turn around” I say to my wife. “We’ll be going in exactly the right direction.”

It’s the same sky. Pasadenacalifornia or Parisfrance look out into the same night and lie underneath the same stars. Fly 12 hours, miss a sunset and sunrise, forget the language if you want, but Regulus will still be there. I used Regulus once to get myself unlost while driving in New Jersey trying to figure out the direction of the shore (my friend in the car with me couldn’t figure out why I pulled off the road, stuck my head out the door, and looked up, before making a U-turn, but that was the best you could do pre-GPS navigation) and used it to find Notre Dame.

I’ll show it to Lilah when I get home. “Hey Lilah, that star is called Reguls and I could see it from Parisfrance” and she might find it wonderful and mysterious and amazing that you can see the same thing from such different places. Or she might ignore me and say “Daddy Daddy I’m going to draw a picture of a ghost for you” or who knows what else. But I will remember that it is wonderful mysterious and amazing that that’s the same star that showed me which direction to turn on a tiny street after midnight in a big city halfway across the world.

[next week: a name for Orcus's moon. I haven't had a chance to read any of the suggestions yet (being on vacation in Paris), but I see that there will be many many to chose from. Stay tuned.]

Lilah Brown's Planets, Part II (or, Season II preview)

Friday night my wife and my 3 ½ year old daughter Lilah picked me up at work to go have some dinner. When I opened the car door, Lilah, who it appears was about to explode from waiting to tell me something, blurted out “Daddy, daddy, daddy LOOK!” and pointed off to the west with an excited look in her eye. I followed her finger to a spot above the horizon where a thin sliver moon was shining down with Venus just a finger width to its right. “It’s Venus and the moon,” she breathlessly exclaimed, “and the moon is little but it is pretending to be full,” her words to describe the ghostly outline of the full moon seen in the background of the bright glint of the crescent moon.

“Daddy daddy daddy do you remember when we saw Venus and the moon and Jupiter, too?”

I do indeed remember that. That moment was the December crescent moon, three full lunations ago. It was also the moment that I like to think of as the final episode of the first season of Mike Brown’s Planets. Like any self-respecting TV production, I’ve been taking a summer hiatus. It’s just that my hiatus occurred during southern summer rather than northern summer.

I’m not sure what TV production crews do during a hiatus but we’ve been pretty busy here at Mike Brown’s Planets, doing a bit of science. You’ll get to hear all about it in upcoming installments. Some of the highlights upcoming include:

Name a satellite of a Kuiper belt object! I’ll tell you about the Kuiper belt object and its satellite and then I’ll take suggestions of what to name the satellite (and why). The best suggestion will get forwarded to the IAU as the official recommendation.
Life, death, and the Kuiper belt.
More and more and more moon shadows. Last season readers here were the first to hear about the ongoing shadow crossing of Haumea by Namaka (and why they are both important and cool). Much much more is to come (and you can read more about it in an ongoing technical blog intended more for research astronomers, but, nonetheless, occasionally entertaining)
My father, rocket scientist, RIP
A (slightly belated) look forward at discoveries that might be made in 2009 and a look back at the 2008 predictions to see how many, if any, came true.
Why Pluto is still not a planet and should remain that way.
Things in the sky that make me smile.

Stay tuned for Season II!

Lilah Brown's Planets

Since late summer, my three year old daughter Lilah has been mesmerized by Jupiter. Every night for a few months now it has been high in the evening sky, one of the first things to pop out of the murky twilight and reveal itself night after night after night. Back in the summer we would have to go outside right at her bedtime, when it was just barely dark enough to make out Jupiter, so she could say good night. These days it is plenty dark as we drive home every day, and , for her, the highlight of the drive is the moment after we’ve climbed the little hill to our neighborhood and we take the final left hand turn to point west, and Jupiter suddenly appears in her window, high enough in the sky to even be seen from the moderate depths of her child car seat.

Anyone who, like Lilah, has been following Jupiter has noticed that it is no longer the king of the evening skies. A while back Venus crept up into the twilight to start to steal the show from Jupiter. Or, at least, in Lilah’s view, to share the show. She went from having only one planet to now having two planets to say goodnight to every night.

Lilah sees planets everywhere. You never quite realize – until you have an obsessed 3 year old – how prevalent images of planets are in everyday life. She’s got them on her lunchbox (a gift from friends who thought it would be funny if Lilah carried a lunchbox where Pluto is a planet); she sees pictures in magazines and catalogs; she sees mobiles and puzzles at stores. I would tend to just walk by them without noticing, but she always runs up – “Daddy daddy daddy daddy LOOK!” She always quickly picks out Jupiter (the big one) and, of course, Saturn. She recognizes the globe-like look of Earth. And she gets Venus right more often than I think she should.

A few nights ago, after a long cloudy spell when we couldn’t see the planets at night, Lilah looked up at the sky and was a bit startled. “Daddy daddy daddy daddy daddy daddy daddy LOOK! Jupiter MOVED!’ And she was right. While Venus and Jupiter had been slowly edging closer to each other over the past few weeks, you wouldn’t notice it unless you were watching closely. But now they were suddenly so close that even a three year old could look and see that something had changed.

As much as I am charmed by Lilah picking out pictures of planets in magazines to show me, having her point out to me that Jupiter moved was – for me – the pinnacle of planetary charm. While most kids and adults can name the planets and point out pictures, almost nobody notices the real thing even when it is blazing in the evening sky. Planets are not just things that spacecraft visit and beam back pictures from. They’re not just abstractions to put on lunch boxes. They are really there night after night after night, doing what only planets do: moving.

Last night – Saturday – the show got even better. The sliver moon showed up low in the early evening sky anda began working its way toward Jupiter and Venus. For half of the month, Lilah and I watch the moon get bigger and move east night after night in the evening sky, so we both know what is going to happen next. Based on how far the moon is from Venus and Jupiter, it looks like on Monday night the moon will be packed tightly in the evening sky with Jupiter and Venus. It will, I suspect, be a spectacular sight, with the three brightest objects ever visible in the night sky in an unmistakable grouping in the southwest just after sunset. It’s the sort of site that I think – that I hope – will make even non-night sky watchers suddenly look up and wonder. And when they look the next night, to see if it is still there, they will notice the moon has already moved further east and gotten a little bigger, and they will see that two other bright lights – Jupiter and Venus – are in slightly different spots. Maybe even a person or two will follow the moon’s movement for the next week as it grows to full. Maybe a lucky few will watch as Jupiter gets lower night after night, leaving Venus alone in the sky by next month. It’s a show worth following. I know Lilah and I will.

I’m on a flight across the country tonight. I touch down long after Jupiter and Venus and the Moon will all have set in Florida. As I was packing my bags this morning Lilah asked: “Daddy, are you going away to go talk about planets?” Yes, Lilah. I’m going away to talk about planets. I forgot to tell her, though, that I’m going to see some, too. I was sure to pick a window seat on the south side of the airplane so I could watch the show from the air. And when I arrive I’ll call back home and tell Lilah all about it and tell her to go outside right now and LOOK! she can see all of our favorite planets and LOOK! the moon has moved and grown and I’m sorry that planets are taking me far from home tonight but I’m glad we have these here in the sky to share tonight and forever.

Moon Shadows, Interruped

I had intended today to talk more about moon shadows and telescope strategies, but I'm distracted by Google Earth, satellite weather images, and LA Times updates.

Yesterday as I stepped out of the gym on the Caltech campus in the middle of the afternoon (Lilah's nap time is a good time to play squash), I looked up at the sweeping view of the mountains that greets you in many places in Pasadena. This time, though, the first thing I noticed was a plume of smoke coming out of a canyon to the northeast. Which canyon? I quickly zoomed in on some of the familiar ridges and valleys of the San Gabriels to figure out exactly how far away the fire was. How far the fire was from my house where Diane was home, Lilah was asleep. As far as I could tell, it was about 5 miles to the east of our house. Five miles is a long distance for fire on a day when the wind is essentially still. But still. I dropped my gym bag, fished through it to find the phone, and dialed home. Diane answered.

"Where's the fire?" I breathlessly asked.

"Um, what fire?"

This answer was probably the best she could have given. I now more calmly explained to her what I was seeing.

I got in the car and drove back to home. On the freeway you had a nice view, now, of a burning ridge. This fire was definitely not a little spot fire that was going to quickly get put out, but from there I could tell it was pretty far from our house. When I got home I pulled up Google Earth and tried to reproduce the exact view I had had from the freeway. I showed Diane. There. That ridge. Pretty far away.

Last night we had friends over for dinner and, as they got close enough to our neighborhood to see flames a few miles away, they called to say "Hey, isn't that fire kinda close to your house? Maybe we should have dinner at our house instead."

It was OK. Nothing was really close. I surreptitiously went inside now and then to check on the news web pages to see if anything was going on. Not really. Some hikers had to be evacuated. Some boy scouts had been temporarily trapped. The fire would be contained soon. I checked the satellite weather image, on which you could see the plume of smoke heading out to sea. It looked undiminished.

This morning we awoke to something now familiar. As night falls and air cools, the ash that has been lofted into the air all day long falls to earth. The ground was covered in gray flecks and bits. The smell of smoke had invaded the house through the windows we had kept open all night. The sun, rising to the east, on the other side of the fire, made a hazy red glow on the wall of the canyon we could see from our bedroom window.

The helicopters started early. We hadn't seen too many yesterday, but now there numbers were definitely increased. Fire trucks went screaming down the road below us.

Curious to see how far the fire had spread, I took Lilah -- still in pajamas -- and drove down the hill in the direction of the smoke. Whereas yesterday the fire was easily spotted and sharply defined, it was now tough to see anything through all of the smoke. I couldn't tell where it was, but I could tell it had grown overnight.

Sunday plans must go on. Diane had a work event and left. Lilah and I went swimming under the hazy sun. We ate grilled cheese sandwiches, played with finger puppets of the three little pigs, did a little roving hide and seek throughout the house, and finally Lilah went to sleep for her nap. Curious about the fire, I looked to see if I could find any news.

I guess there was a reason for all of the helicopters and firetrucks that seemed so close by. Houses were being evacuated. The fire was still out of control. I got out Google Earth once again to try to interpret what I read. The evacuations are all in the upper part of the city of Sierra Madre, the city immediately to our east. When I finally found the evaculation map I realized that houses 1 1/2 miles from ours were already evacuated.

It's not really that close. But still.

This time it was Diane's turn to call: "I just heard Sierra Madre's been evacuated; should I come home?"

"No. We're fine."

And we are. Really.

We live in a fire zone. Our house overlooks a wild canyon that is right now gloriously flowered, but come the hot winds of the summer and fall will be dead brown fuel. We do what we can. Our roof is fire resistant composite. We thin vegetation. Our swimming pool is connected to a fire hydrant on the street so that a fire truck could easily use the water to douse our lower neighbor's house (but not ours; it's only gravity fed, so it could only help the people below us; sadly, the house above us has no pool that would help us out similarly).

We have evacuation plans with multiple contingencies. Distant fire with plenty of time to plan? Pack both cars and take this this and this. Fire in the canyon right below our house? Take Lilah first, cats if there is time, and run like hell. What if the only road down the hill already has been overtaken? There is a trail behind our neighbor's yard that quickly goes down to a safe spot. Fire on all sides? Jump in the pool and breath through wet clothes.

We won't need any of these plans for this fire. They'll have it out tomorrow or the next day and, more likely than not, nothing significant will have been lost. It's the springtime. It's early. The plants still have some moisture left in them. The winds are not blowing. The real fire season has not yet begun.

These sorts of fires happen all the time in southern California. It will likely not rate more than a 4th page of the local news blip in the LA Times tomorrow morning.

But still. Right now Lilah remains soundly napping. Diane is at work wondering what is going on, and all I can do is sit and check the news sites, watch the helicopters to see how close they drop their loads of water, and stare at Google Earth and speculate on the interaction of slope direction, wind speed, and fire vectors.

Someday, presumably, it will be more. Plans will be put into action. We'll sit below with binoculars staring up at the hillside trying to figure out how close the flames have gotten. We'll call our home telephone to see if the answering machine picks up. For now, though, we do what we can, hope for the best, and always breath a little easier when the winds don't blow.

Tomorrow normal life will continue. Which, for me, means dealing with the technical aspects of our upcoming observations of the Hubble Space Telescope. Our proposal to search for moon shadows on Santa was accepted on Thursday, and observations will start in 2 weeks. That's what meant to write about today, before being interrupted by smoke and helicopters and fire.

Tiny Bunnies

This morning my 2 ½ year old daughter Lilah opened the front door to find the tiniest Easter basket I have ever seen, filled with candy, bubbles, and stickers. My suspicion, as yet unconfirmed, is that Easter baskets everywhere were equally tiny today, and that it is all the fault of the moon.

This is the third Easter Diane, Lilah, and I have spent in our house up in the foothills above Pasadena. After last year’s record low rainfall, Easter – and springtime in general – was marked by an intensifying of the brown in the canyon in our backyard. That same brown all over southern California contributed greatly to the intense wildfires that swept the region last fall. The small-scale wildlife that was abundant in our backyard two years ago – rabbits, squirrels, even the occasional bobcat and [once] black bear – generally disappeared.

This year the occasional torrential rains typical of southern California winters returned and gave everything a nice soaking. The canyon in our backyard is awash in green and is about to explode into a sea of yellow mustard flowers. Even the great canyon oaks which dominate the canyon and are designed for long term droughts have a fresh sheen from the first set of new leaves in two years. Squirrels have been running around chasing the droppings of the bird food we keep out for the finches and sparrows and blue jays and titmice. Some as-yet-unknown small animal sneaks through the fence around my garden and has been nibbling on the leaves of the artichokes. The first sweet pea pods are forming. Lilah has a small box with caterpillars waiting to change into butterflies and a small bucket with tadpoles waiting to change into frogs. With the equinox passing just two days ago, it certainly feels like spring has come.

But the bunnies? Two year ago, our first Easter, the connection between Easter and bunnies was obvious. They were everywhere. You couldn’t open a curtain or door in the morning without stumbling on a new set of bunnies nibbling on the bushes, hopping down the street, playing in the grass. It was easy to explain to Lilah that the Easter bunny was certainly on his way. This year, though, the bunnies are almost unseen. One or two tiny babies have been spotted, but not the abundance of two Easters ago. What is going on?

I think the fault is not with the bunnies, but with Easter. Easter is awfully early this year, and it is likely that no one told the bunnies to start earlier. Two years ago Easter was on April 16^th, a full three weeks later.

The bunnies should, of course, be watching the sun and the moon to know when Easter is. This year, in particular, with Easter so early, the method of choosing the date of Easter has been much in the news. Easter falls on the first Sunday after the first full moon after the Spring Equinox. The Spring Equinox is, of course, the precise midpoint between the long night of the Winter Solstice, back in December, and the eternal twilight of Summer Solstice, in June. On the Equinox, the day and night are of equal duration (the origin of the name) all around the planet. Also, the sun rises and sets directly east and west. Thus, one way to know that the equinox is near is if, like me, you live in a town where most streets are on a north-south-east-west grid, you will start to notice that the sun is always setting (or rising) precisely in your eyes as you head westward to go home at night (or eastward to leave home in the morning). That means the equinox.

Even the equinox occurred a little early this year. The precise moment when the sun was precisely over the equator (another way to define the equinox) was 5:48AM GMT on March 20^th, which translates to 10:48PM PDT on March 19^th here in Pasadena. Last year it was 5:07PM PDT on March 20^th. In reality the equinox didn’t change, just our calendar. With leap year this year our calendar is behind by almost a day. It will catch up again over the next 4 years.

The full moon, which could come at any time over the next four weeks, happened to follow closely this year, occurring at 10:40am on March 21^st. And it was a Friday, so the next Sunday was only 2 days later. Today is March 23^rd, and it is Easter. The bunnies could have gotten it right by watching to see when night and day were equal lengths, looking for the next full moon, and watching driveways everywhere for an extra fat morning newspaper to know it was Sunday and thus Easter.

Except that this is not really correct. I used to imagine teams of astronomers sitting around with precise measuring tools to declare when the equinox had occurred to set everything in motion. I used to smugly explain all about astronomy’s role in determining the date of Easter to anyone who would listen. I used to wonder if it ever happened that the full moon followed the solstice by minutes and made for instant Easter. But, this year, I finally looked up who really decides. The answer is a bit disappointing, at least to me. For the purposes of Easter-determining, the equinox is on March 21^st. No astronomer needs to track the sky; we can all just look at the calendar. The precise moment of the full moon? Not actually important either. Officially, centuries old calculations are used, which differ from the actual date of the full moon by up to two days.

Still, I could at least be smug in my amusement that yet again a major Christian holiday had clear ties to early astronomy and astrology and was designed to co-opt some sort of Pagan equinox celebration. Except, when I read more, I realized even that was not true. The timing was an actual attempt to figure out an actual date of the Last Supper, for which there is some indication that it was slightly before Passover. Passover, in the Hebrew calendar, occurs on the 15^th day of Nisan. The first day of a moon was originally declared to occur when credible witnesses had seen a crescent moon. Nisan, which approximately translates in Babylonian as “until the barley is ripe,” was declared based on the critical springtime crop. It occurred around the time of the equinox. Fifteen days after the start of Nisan the moon would be full. And Passover would begin, on the day of the first full moon after the equinox.

So my smug amusement is totally misguided. Instead I should have understood and respected the observational, agricultural, and astronomical aspects of the much older Hebrew calendar. It is quite amazing that such a calendar designed thousands of years ago still underpins the basis of the day of one of the larger religious holidays of the year. But even with my newfound respect I can see the problems. The bunnies, even if they knew the astronomical rules, could never read all of the ancient tables. They will never know ahead of time when Easter is here. And occasionally, when the moon is right (and the tables are right too), Easter will show up weeks too early and then bunnies will not have grown. Easter baskets everywhere will have to be downsized so the tiny bunnies can carry them to front doors.

Luckily for me, at 2 ½ Lilah doesn’t yet know what she is missing. But next year, as a 3 ½ year old, she may catch on. Happily, next year, Easter is not until April 12^th, and, once again, the bunnies will be running all around the yard, hiding candy and eggs as they go.

Winter Rain and New Moons

The winter rains have returned full force to southern California after a two year absence, and the fact that they have come during the new moon is making me unpleasant company.

It’s not that I have any later were-wolf-like tendencies that cause moon-related outburst, nor that I believe in any supernatural connection between the rain and the moon, it’s just that the new moon is prime astronomical observing time and January is – or could be – a prime astronomical observing month. And the rain is stealing it away.

We’re still looking for planets, like we have been for a while, but this time things are a little different. We can see the final end of our searching in sight, and, this time, the final end will come not because we have finished looking everywhere in the sky, but because the camera that we have been using for the past 7 years is finally being retired in October. This impending retirement suddenly puts a new urgency in our searching, for any patch of the sky that we miss due to rain, clouds, fires, broken equipment, or anything else will remaining unsearched, potentially for years to come.

And we have had them, the clouds and rain (to say nothing of fires). Fabulous clouds and rain, even. In one weekend we got more rain than the total amount of rain my two and half year old daughter can remember over her entire life. She and I put on rain boots and walked down to the canyon below us, a place where we had been many times previously in her life, long ago with her asleep in a backpack, and, more recently lately, with her walking along beside until she tires. Last week, not knowing what was coming, I told her “Look there at those rocks! Sometimes when it rains a lot the water comes and covers them up and makes a river here!” So, during a brief lull in the rain, we went back down to the canyon to see, and the water was everywhere. You could have almost gotten by with a little kayak in the middle of the creek that was a dusty wash days earlier. “Daddy, water!” she said. “There’s water in everyone’s garden!” (She calls any park “everyone’s garden” which seems like an appropriate name to me). We found a shallow slow moving side stream and jumped and splashed and reveled in the water from the sky.

My point here is that I like the rain. Really I do. But, please, can’t we keep it confined to when there is a full moon? Every month there is about a week-long period centered on the full moon when looking for planets is simply not useful. Just like we need to avoid the bright lights from the city, which wash out the stars at night, we also need to avoid the bright light of the full. But, unlike the city lights, there is nowhere we can go to escape the light of the moon, so we have no choice but to close up for a week and wait for our search-light-bright nemesis to pass.

And then, for that week when the moon is full and the telescope is closed, then I really pray for the rain to come. Buckets of rain. Thunder and lightning. Frogs from the sky. Anything that nature can throw at us. During the week when I know the moon is full I look at the sky every night and revel in the clouds and precipitation and wish for more more more. My daughter and I giggle at the sound of the rain pounding the roof and marvel at the new drainage system we just finished installing which prevents the backyard from becoming a shallow inadvertent swimming pool. Give us more! Nothing is more fun than rain.

Nothing is more fun that rain, except when the moon is new. Then we have planets to find, and every cloud in the sky or forecast of showers several days off, or hint of a moist breeze blowing from the Pacific feels like theft. Part of the sky is being taken away, and I’ll never have the chance to look there again. It’s a strange theft; you don’t know for sure what, if anything you’re missing, much as if someone stole packages from under your Christmas tree that may or may not have had anything in them. In some ways, that theft is even harder to take, because the possibilities of what might be gone are almost limitless.

I’m not very fun to be around when it is raining and the moon is new. I would recommend avoiding me altogether. Or, if you must confront me, pointing out how nice the forecast looks in a few days. Or barring those, ask how my daughter is enjoying the rain. My scowl might break a little. But, really? Total avoidance is probably for the best.

Tonight, at least, the skies are looking clear. The last thing I’ll do before going to sleep is the same as the first thing I’ll do when I wake up tomorrow morning. I’ll walk out into my backyard just before sunrise and scan from horizon to horizon looking at the most prominent of the stars still peeking out of the brightening sky. I’ll scowl at any clouds that I see, and I’ll try to decide if perhaps they are just very local or short very lived or otherwise unproblematic. Or, more likely these days, I’ll step outside in the morning and see the whole sky covered in clouds, or I’ll feel raining coming down, or a thick morning haze will fill the entire LA basin. Then, as the gloomy sun begins to rise I’ll look right at the spot in the sky where we should have been searching for planets last night, and I’ll wonder what might have been in that now-stolen package and how many years will pass until finally someone gets to open it under their own tree.

Pages