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.



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?

Yelping at Saints

If your skies have been clear for the past week you might have been noticing -- as I have been -- the slow but unstoppable growing of the moon. There's nothing new here. It does essentially the same thing every 28 days, but it is still a show worth watching.
In my backyard I see this: each night as the moon moves further and further in its circle around the earth and we see more and more of the illuminated half, the moon is getting just a little brighter. In a few days, as the moon finally goes from just-barely-not-full to finally-completely-full, the moon will finally brighten its last incremental amount and it will be its brightest of the month, though only a little brighter than it was the night before.
This gentle brightening to a muted peak sounds prosaic and reasonable. But it is not true.
I remember once being out on a backpacking trip in the wild mountains inward of the Pacific coast south of Monterey. Some friends and I had hiked all day to make it over a range and down to the bottom of a creek where a little stream of hot water poured out of the earth making a tiny pool in which to soak sore legs and shoulders. We camped a bit away from the hot pool, ate a warm dinner as the sun was going down, and finally began climbing our way to the top of the little ridge separating us from the hot spring. We didn't even bother with flashlights in the dark because the full moon had made the entire woods faintly glow -- plenty of light to get around at night even in the dark of the wilderness. As we had almost reached the top, though, somebody silently flipped a switch and a blinding spotlight was suddenly tracking us from the ridge.
This was miles away from any roads or machinery down a long windy trail, so perhaps I could have reasoned my way out of the situation given a little time for relaxation, but, in the instant, I did what I think most anyone would do when unexpectedly illuminated by a spotlight deep in the woods far from where anyone or anything should be: I yelped. Loudly.
My yelping didn't affect the spotlight, which refused to flinch. It refused to flinch, I realized an embarrassed moment later, because it was no spotlight, it was the moon. It had been hiding behind the ridge until we had gotten near the top, and as we rose over one bump it suddenly revealed itself like the flip of a switch. My credibility as a young astronomer (I had just started graduate school that year) was seriously diminished amongst the friends who had seen me frightened of the moon.
Which is to say that the full moon is really bright.
The fact that the full moon is bright is perhaps not a startling fact, but what is startling is that if I had been coming over the ridge on my way to the hot pool and I had seen the moon a day earlier or a day later, I would never have mistaken it for a spotlight.
You don't have to take my over-tired-from-hiking-all-day's impressions for it. If your skies are clear this week as the moon is finally puffing towards full, go outside and see for yourself. Go out on Saturday, two days before the full moon, and look around. Check out the barely visible shadows. See what fuzzy shapes you can make out in the distance. Look up and notice that the moon is definitely not fully illuminated, but it is getting close.

Go out Sunday. To really do the job right you should go out an hour later than you did the night before, since the moon will have risen an hour later. Look around. You probably won't be able to tell any difference at all from the night before. Same vague shadows, same fuzzy details. And then look at the moon. Definitely bigger, but one edge is still a little flattened. Tomorrow it will indeed be full.
Finally, go out on Monday, an hour later still if you can. Stare right at the moon, if your eyes can stand it. It does look like a spotlight up there in the sky. It is much brighter than it was just the day before. Look at the now-crisp shadows on the ground and the sharp details on the rocks and the plants that you can now pick out. Now go ahead, if you need to, and let out a little bit of a yelp. I'll be understanding.
What is going on with the moon? How can it get so much brighter in just a day? Who turned on the spotlight?
In medieval paintings, saints and anyone else holy are always depicted with a halo around their heads. Unlike modern halo depictions, which look like a gold ring hovering slightly above the hat line, these medieval halos appear more like a general glow coming from behind the entire head. Whenever I see one of these glowing medieval halos I think about how bright the full moon is.
I have a hypothesis -- totally without the benefit of supporting research, necessary expertise, or, likely, even minor merit -- that the medieval painters painted halos like this because they had seen such halos around their own heads. And I know what the painters saw, because I have a halo around my head, as well.
Here's another experiment to try. Go outside on a bright sunny day and start watching your shadow. Walk along until you find a place where the shadow of your head is falling on grass. Focus on your head shadow while you continue to walk, letting the background grass blur in you vision. You will gradually notice that there is a diffuse glow around the shadow of your head. It won't be around any other part of your body, and you won't see the slightest hint around anyone else's head. Point out your halo to any else and they will see precisely the same thing: a halo around their own heads and nothing around yours. Everyone is holy to themselves.
In reality what you are seeing is not some sort of corporeal representation of your own ego or a mystical aura of self-realization, but simply a literal trick of lights and shadows. When you are looking at the shadow of your own head, you are looking, by necessity, directly in the opposite direction of the sun. Stop focusing on your glowing halo for a minute and now focus on the grass itself. You'll notice that in the region where your halo is you will not see a single dark spot due to a shadow of one blade of grass on another. There can't be any shadows; with the sun directly behind you, any piece of grass that you can see can see the sun, so it can't be in shadow. Start looking away from your head shadow and you notice that you are now starting to see collections of tiny shadows, so the overall scene gets darker and darker even though it, too, is fully illuminated by the sun. Your halo is simply the total lack of shadows that can only occur when you are looking almost exactly opposite the sun. I've seen my halo from many places, on many surfaces: on grass or rough dirt or asphalt while walking, even on the tops of a forest full of trees while looking out of the window of an airplane flying low enough right before landing that I could pick out the shadow of the fuselage and see a beautiful glowing ring around. Anywhere you have sunlight and a surface rough enough to make millions of tiny shadows you get to glow the glow of the saints.
And so it is with the moon. When you look at the full moon you are almost looking at where the shadow of you head would be. The sun, though it has set over the horizon, is directly behind you as you face the full moon. If you could see down to the surface of the moon, you wouldn't see a shadow anywhere, not in the craters, not amongst the craggy mountains, but, more importantly not even at the finest scales of the rocky dust that covers most of the surface. The next day, when the moon is just past full, the shadows will begin to reappear and the spotlight will be extinguished.
It happens every month. It's just a trick of light and shadows. But, every now and then, I still look up at the full moon and think about saints and I feel a little bit of a yelp deep inside.

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.

Vague hopes and just happenings

Last week, when writing about potential discoveries in 2008, I admitted to having some specific ideas, some vague hopes, and that some might just happen. I wrote about some of my specific ideas for the year. Here I’ll talk about the other two – and the much more common – types of discoveries.

The “vague hope” types of discovery are very different from the “specific idea”, or, to be more specific, the make-a-hypothesis-and-test-it types of discoveries favored in explanations of the scientific method in 8th grade classes.

The best example from my own past that I can give us this type of vague hope was the discovery of Eris itself (the Kuiper belt object larger than Pluto that caused the uproar over Pluto’s status and finally forced the demotion of Pluto to a dwarf planet. You can read much more about Eris on my detailed site). When I started scanning the skies almost a decade ago looking for large objects in the outer solar system, I certainly didn’t know what specifically was going to be out there, but I knew that there was a not bad chance that we would find something bigger than Pluto eventually (though I will admit that at one point midway through the decade I contemplated declaring the search over, thinking we had found all there was to find of interest. One of my students eventually talked me out of it). On January 5th 2005 (3 years ago today, even though it feels like a much longer time ago to me), I finally spotted the object that we first called Xena -- then temporarily became named 2003 UB313 and finally became Eris -- moving very slowly past the stars on my computer screen. It’s not that we had had a hypothesis to prove, just a realization that if you search more of the sky than anyone else has since the invention of the computer and digital cameras, you will certainly find things that no one has before. Will the thing you find be bigger than Pluto? Maybe yes, maybe no, but, as long as you are hoping, you might as well hope in the direction of bigger.

Now to 2008. The survey of the skies that led to the discovery of Eris and the other dwarf planets ended more than a year ago when we finally had scanned almost all of the skies that can be seen from our telescope at Palomar Observatory. But after spending most of a decade searching the skies for newer and larger bodies, it was hard to actually quit. What to do? Start over again. But this time I am doing it with the knowledge gained from doing it the first time, so this time we are doing everything – I hope – right. In practice, the most important thing that this means is that we are extending the survey to find extremely distant objects that we would have missed the first time around.

Why? Vague hope. Or perhaps it is better called “directed hope.” From our discovery of Sedna, which spends most of its time far far away from the sun, we realized that there might well be many many objects out at those distances, and that some of them could be quite large indeed. By “large” here, I am talking about something perhaps even the size of Mercury or of Mars (hope. remember: the key here is hope). I certainly don’ t have a specific scientific hypothesis supported by equations and calculations that some such object is out there, just a realization that it plausibly could be and that no one has ever done a thorough search.

So that could be one very exciting answer for discoveries of 2008: a Mars-sized body orbiting at perhaps twice the distance of Eris. Amusingly, by the current IAU definition, such an object would still be called a dwarf planet, though it would be a dwarf bigger than some real planets. If we really did discover such a thing it would probably re-light the planet definition fire, and we would all get to watch astronomers begin arguing once again.

To be honest, I have to admit that I think finding such a beast is a bit of a long shot. The main reason is that even though I am pretty convinced that such large dwarf planets are out there floating in the same region occupied by Sedna, they are likely to be too far away for our modest telescope at Palomar Observatory to see. Really, we would have to get pretty luck. But again: directed hope. It just might be there, and we won’t know until we look.

Finally, some discoveries are the type that I said just happen, though, really, that is not quite the right phrase. No discover ever just happens, I don’t think, but, sometimes, while you’re looking for something else, or examining something just because you’re curious, or trying hard to understand one little detail of something that just doesn’t make sense to you, something will pop out that you had no idea was coming.

The discovery of Sedna was like this. We were scanning the skies hoping that we might find something bigger than Pluto, knowing that we were bound to find many things than no one had ever seen before, but we never anticipated anything like Sedna.

When I first saw Sedna I wasn’t even convinced it was real. It was so faint that I thought it might just be a recurring smudge on the pictures I was looking at. The first email I sent out to Chad Trujillo and David Rabinowitz, the two guys with whom I was working, said “Not that I think it’s actually real, but the thing I might have just found is really really far away and really really big.” It was true, which is why we are now looking for things even bigger and further away.

Sedna orbits in a region of space that astronomers expected to be essentially empty, so it really had never occurred to me that when we began hunting in the skies something like Sedna might show up in our snares. Sedna is smaller than Eris by perhaps 20-30% and thus smaller than Pluto, so it didn’t get nearly as much press coverage as the Eris discovery, but, of the two, Sedna is by far the much more interesting scientific discovery. Eris’s main importance is less in the scientific knowledge that something bigger than Pluto exists but much more in the cultural importance in that it was the discovery that finally drove home the fact that Pluto is not a unique oddball at the edge of the solar system but simply one of the largest members of a much more extensive population. But Sedna tells us something we never knew before. What? It is still not clear; we’re working hard to understand all that Sedna says, but by the time we are done I hope that Sedna is the beginning of an intricate story of the birth of sun in a crowded cluster of stars which eventually caused Sedna to be peeled out of the inner solar system to become part of this new still unnamed region beyond the Kuiper belt. Stay tuned. There are other possibilities for what it might mean. But whatever it turns out to mean will be something we never even considered when we first started looking across the sky.

What might we discover unexpectedly in 2008? There is no way I can tell, of course, but I can at least give some areas of possibility, because all of these accidental discoveries come about with a lot of hard work to make the accidents possible. If I had to place bets on what project is most likely to lead to something like this, I would have to again say the new sky survey. Anytime you are looking over vast areas of sky in ways that no one ever has before your chances of having a good accident are high. But that is not the only project my group and I are working on these days – we’re thinking about storms on Titan, giant collisions and icy atmospheres in the outer solar system and more – so one of the other projects may sneak in as a long-shot. Or something new may come along unexpectedly.

Happy third anniversary of the discovery of Eris, and hope for discoveries – expected, hoped for, and accidental in 2008.