Saturday, December 23, 2006

Holiday Hiatus

There is a remarkable breakdown of taste and intelligence at Christmastime. Mature, responsible grown men wear neckties made of holly leaves and drink alcoholic beverages with raw egg yolks and cottage cheese in them. ~P.J. O'Rourke

Since my employers thoughtfully give me some time off at Christmas and New Year's, just long enough for the equipment to break down while I'm enjoying new toys, football, and food, Explorations will take some time off as well. In the meantime, if you must have a fix of weblog, peruse the archives. I'm sure you'll find something in there of interest.

Oh, and we can all be thankful that the shuttle returned safely before a) it ran out of power, and b) the year changed (since its computers can't automatically switch over to a new year).

Have a very Merry Christmas and a Happy and Safe New Year.

Thursday, December 21, 2006

Traveler's Tales

When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it—that is knowledge. ~Confucius

Scientists had high hopes for the Stardust mission, and, so far, they aren't being disappointed.

Stardust spent five years catching up to comet Wild 2 (pronounced Vilt, for those of you who wish to be precise), caught a myriad of tiny particles in its aerogel-filled collectors, and high-tailed it back to Earth, landing in the Utah wilderness softly (unlike its friend Genesis, who pancaked in the desert). After an exciting hour or two of searching, the team recovered Stardust, and the scientists have been going slightly crazy ever since.

There are so many impacts in the aerogels that the public has been enlisted to search through the collector images to try to identify promising particles. Stardust will be yielding information for years to come.

It has already served up some treats. One particle has been discovered that is apparently not from our solar system. This is determined by the oxygen isotope content. This tiny bit has 150% more of the heavy oxygen isotope than it should have. Comet Wild seems to have collected some detritus from outside our immediate neighborhood.

Most of the samples studied so far would indicated that Wild, like many such objects, formed out in the Kuiper belt and has only lately wandered into the inner part of the solar system. At least, that should be the case, but one of the samples returned isn't from the icy reaches beyond Pluto. It seems that it is something called osbornite, which forms in temperatures of 3000 degrees Kelvin.

That's hot, and how something heated like that got into the comet is a mystery. Scientists can only speculate that the nebula in which the Sun and planets formed was more active than previously imagined. Then there's the organic material.

"We didn't expect any organics to survive" from the impact and heat during the collection process, said Livermore researcher Sasa Bajt (see Resources for the Science Daily article). "But we found a rich variety of organics that were both oxygen-rich and nitrogen rich compared to organics previously found in meteorites.” Finding organic materials lends considerable credence to the theory held by some that life on Earth was “seeded” from extraterrestrial sources.

Even the idea of what a comet is has come under scrutiny. For years, the general theory of cometary makeup was best described as the “dirty snowball” scenario. All comets were formed away out there somewhere out of gases and light materials left over from the creation of the Sun and planets. Away out there was where they stayed until perturbed by something or other, at which point they would come into the inner planetary area, outgassing geysers of some sort of melting matter as they neared the Sun. The biggest question was whether they were relatively solid or whether they were just jumbles of rubble loosely held together.

Now, it seems that every time we get near a comet, we find out something different. Wild 2 has been both very hot and very cold. Tempel I, target of Deep Impact had its own surprises.

Deep Impact was a remarkably ambitious attempt to send a probe (if one can call something the size of a washing machine a “probe”) crashing into a comet to study the ejecta and possibly see into the comet. The Deep Impact team was both delighted and disappointed by the result. They were elated that they actually hit the bloody thing. After all, you've got Deep Impact hurtling headlong toward a large fast object; at full tilt, you push off a probe which has its own navigation system and swing the main satellite out and around so it won't hit Tempel. By some miracle, the probe actually gets where it's supposed to go, and the result is a spectacular outburst of light.

That was also the bad part. As Deep Impact whizzed by, it couldn't see into the comet at all because the glare was terrific. But, the Swift X-Ray telescope saw something, and that was odd, because it wasn't supposed to. No one is quite sure yet why there was an outpouring of X-rays from Tempel I and why it should have lasted for 12 days. In fact, optical telescopes only saw optical flaring for about 5 days, so the mystery of what was going on in the remaining 7 is perplexing.

Amazingly for the amount of vaporization, it also turns out that Tempel is only 6% water, with the rest being a rather fragile agglomeration of dust. So where did the X-rays come from?

One of the Deep Impact scientists put it best, soon after the successful probe impact. At the time, we had taken a close look at three comets, Halley, Wild (photographic returns; the samples were still in route), and now Tempel. Here we were, expecting comets to be pretty similar in makeup, yet all three were very different. It seems like the more we were learning about comets, the less we knew. It also turns out that we know a lot less about the early solar system than we thought.

Carl Sagan once talked of the Voyager satellites sending back 'traveler's tales.” Apparently, Stardust, Deep Impact, and even Genesis (whose sample collectors are still being diligently cleaned) have new tales to tell us.

We're listening.

Resources:
Stardust's Comet Clues Reveal Early Solar System
"Deep Impact" Comet Spewed Tons of Water, Study Finds
Comet grain confirms early solar system mixed it up
Space Probe Brought Real Stardust Back to Earth
Comet Particles Tell New Story About Birth Of Solar System

Tuesday, December 19, 2006

Hits and Myths

Legend: A lie that has attained the dignity of age. ~ Laurence J. Peter

We do love our myths. The success of "Mythbusters" on the Discovery Channel is tribute to our love of legends (and explosions) both great and small. In addition, the endless programs about UFO's, legendary creatures, and prophecies show that many people just can't get enough of this sort of thing.

Take the Loch Ness monster. People have been seeing this thing since there were people to see it. They have produced pictures, have sworn on a stack of Bibles to seeing it, and have funded lengthy research efforts to find the illusive Nessie. What we have to show for it are some grainy films, some dubious photographs (include one outright forgery), and no sea monsters.

We should expect no more than that. Loch Ness doesn't have enough fish in it to support a large sturgeon population, much less a family of pleisiosaurs swimming around for hundreds of years. But, if one was to assume that somehow Nessie and her mates could eke out a living, there would have to be enough of them to ensure that they could reproduce in sufficient numbers to maintain a population of them in the lake. If you have so many of something so large swimming in an enclosed lake, a sonar survey would have revealed them. One such survey, which featured boats strung completely across the loch, came up completely empty.

Yet people want to believe so much that they can be fooled by the so-called “surgeon's photo.” The photo, taken by someone who was angry at a newspaper that had not paid for his search efforts at Loch Ness, was fronted by Robert Wilson, a surgeon, to give it legitimacy. Long held to be absolute proof of the existence of Nessie, some years ago it was revealed, by Wilson's son, I believe, that in actual fact the photo was of a fake “Nessie” head attached to a toy submarine.

Our oceans are full of exotic and wonderful creatures, like the giant squid, yet people prefer to believe in a prehistoric creature lurking in a Scottish loch.

Then there's the matter of UFO's. No one is more intrigued by the possibilities of intelligent life on other planets than me. I've speculated about since I was old enough to realize that there were other planets. But the bulk of the UFO believers are wrapped up in conspiracies (what would they do without Area 51?), abductions, and metaphysics that they seem to have a weak grip on the realities of the situation.

J. Allen Hynek was the official de-bunker for the U.S. Air Force for years. He left after some time, not because he thought there some some deep governmental conspiracy to hide the “facts” about alien visits to Earth, but because he felt the Air Force was forcing explanations on observations that were truly unidentified. His stand was that there were indeed some things showing up in the sky that we didn't understand, and he wanted to be able to research them. As far as he was concerned, calling every strange sighting a weather balloon was just as bad as calling it a flying saucer.

In fact, Dr. Hynek continued his debunking of faked photographs and hokey abduction stories for years after his retirement, all the while trying to get people interested in investigating more mundane but completely unexplained sightings. He never really got anywhere, but he was popular amongst the UFO set, despite exposing some of their cherished “evidence” as fakes or erroneous interpretations.

The alien abductions always have rankled me. If we visited a planet and found intelligent life on it, would we:
  • a) Spend time observing the planet, attempting to learn how to communicate with the beings?
  • b) Make an immediate attempt to contact them using mathematical patterns?
  • c) Sneak down in the middle of the night, find a couple of drunken yokels, take them for a ride around their solar system, poke them with needles, then return them to the swamp where we found them?
To most UFO enthusiasts, the answer is most definitely c).

A co-worker and I were discussing this the other day, when he, a born and bred Alabamian, offered his opinion on why the abduction-of-drunk-rednecks theory is hokum.

“Listen,” he said, “if some good ole boy is stomping through the woods at night and sees a little green man coming at him, his first thought is going to be, 'I'm-a goin' to shoot that l'i'l green feller. He'll look good on the wall next to my buck and big bass mounts.” And blammo! There'd be one less E.T. left to phone home.

It's strange really how humans hold on to the ideas of the paranormal, legendary creatures, and flying saucers, among other myths. Much of this fascination has to do, I think, for the desire for something beyond the routine word we think we understand so well. People believe in ghosts because it gives them comfort about what happens after death. We like the idea of monsters in the oceans the same way we like dinosaurs; these are monstrous creatures that generate a sense of awe. And we love (and fear) aliens for a variety of reasons, many of which have to do with the idea of finding someone with greater wisdom than we have because they are so much more advanced.

Of course, if they're so advanced, how come they find bayou drunks so fascinating?

What's really ironic about this is that the universe around us is so much more fascinating than most people realize. As Sir Arthur Eddington once said, “Not only is the universe stranger than we imagine, it is stranger than we can imagine.” At the time, Sir Arthur may have been motivated by Edwin Hubble's findings, Einstein's theories, or the blossoming science of quantum mechanics. All of those events were jarring us out of a comfortable parochial sense of complacency, with the realization that not only did we not know everything about our surroundings, but we actually didn't know very much at all.

The average person, though, takes much of this scientific “stuff” for granted. They don't see the challenge of isolating a Higgs boson as all that interesting, while a huge sea monster floating around in Loch Ness is amazing. There's also a little rebellion at work here. Our teachers and the “experts” (whoever they are) are forever telling us what's what. We like seeing their balloons punctured. Of course, balloons are punctured all the time, but the argument over the expansion rate of the universe seems so abstract compared to the possibility that a spaceship set down last week in Biloxi.

There's nothing wrong with keeping an open mind toward myths. In fact, keeping an open mind is what discovery is all about. Investigating the strange has often led to very real discoveries. But the danger is in spending inordinate amounts of time and resources on those myths, as well as a willingness to discard facts in favor of unsubstantiated evidence.

So, keep an open mind toward the mythical, but never close your mind to reality.

Thursday, December 14, 2006

Of Curses and Kings

“You scoundrel, you have wronged me,” hissed the philosopher. “May you live forever!” ~ Ambrose Bierce

Curses

I swear that more Roman artifacts are found in England than in Rome and greater Italy. A recent find is one of those homely little items that connects us with the people of the past, not just the events. In Leicester, England, a “curse tablet” has been found. This is not to be confused with a letter full of curses, which I documented some time ago. As you may recall, one of the letters involved a woman who was scolding someone over a debt. The language was strong enough that the team that discovered it did not publicly release the complete translation for fear of offending the sensibilities of the general public.

As I said at the time, that's such a disappointment because cursing is in such a rut these days that we could use some imaginative foul language.

The curse tablet, on the other hand, has been completely translated. It said:
To the god Maglus, I give the wrongdoer who stole the cloak of Servandus. Silvester, Roimandus that he destroy him before the ninth day, the person who stole the cloak of Servandus.
This supplication is followed by a list of 18 or 19 suspects. Evidently Servandus wasn't into doing extensive detective work; he also wasn't very popular if there was a platoon of people who would gleefully walk off with his cloak.

You've got to admire the simplicity of this curse. “Hey, Maglus, kill the creep who copped my wrap.” Nothing very flowery about Servandus.

This find is the sort of thing that reminds us that people have been people a long time. Some Roman postcards were found some years ago in England. One asked someone to send socks (very handy apparel for a Roman in the chilly north of Britain); another invited a friend to a party. It's one thing to talk of Julius Caesar and Hadrian, mighty leaders of empire whose minions ranged across the world. It's another thing to find that one of those minions wrote home for socks. I can relate to the guy writing about the socks far more readily than I can to Hadrian.

Curse tablets, according to the article, were the sort of thing that ordinary folks used, the wealthy being able to call on the local priesthood (with an appropriate donation) to personally appeal to the gods in their favor. For someone in the working classes, like Servandus, the curse tablet was his main method of appealing to the gods for help. For a working man, the loss of a cloak was a serious loss. No wonder Servandus wanted blood.

Servandus' curse turns out to be more informative than one might expect. His role call of suspects includes Roman and Celtic names, giving archaeologists an idea about the makeup of the population in Leicester 1700 years ago. Many people have an image of the Romans marching into Britain, taking the all the Celts prisoner and sending them back to Rome as slaves. While this happened at times, particularly when local groups rebelled against the occupation, over time the Celts and Romans came to live together, with the locals benefiting from Roman civilization. When the Romans left, the Celts, in many cases, simply took over many of the cities, some of which are major centers today.

But my mind keeps drifting back to Servandus. I wonder if his curse got any action. Probably not, which leads us to wonder if he composed a new one with more names on it. I guess it depends on how many people Servandus thought disliked him.

Closing the Tut Case

A report was delivered at the annual meeting of the Radiological Society of North America that made official the results of a CT scan performed on King Tutankhamen. I am presuming this report was based on the scans taken some months ago in Egypt under the watchful eye of Zahi Hawass. Mr. Hawass was determined to try to find the actual cause of death of the Boy King once and for all.

It has been very popular over the years to ascribe Tut's demise to the machinations of trusted associates or even his wife. The Discovery Axis even enlisted a couple of private eyes to ride back and forth in a jeep in Egypt (or at least it looked like Egypt) for a couple of hours concocting a theory of how Tut was done in. They rehashed a bunch of old canards, finally coming up with a plot by Ay to bash Tut in the head so he could take over.

Sorry, guys. It just didn't happen that way. The simple fact was that Tut's skull never clearly showed the kind of damage a whack on the skull would produce. The CT scan verified that any bone fragments and minor damage to Tut's head came most likely came from the embalming process. Other breaks in his bones most likely came from his brute-force removal from the resins hardened in his coffin by Howard Carter and his associates. The same could not be said of his legs.

It seems that Tut suffered a grievous fracture to his leg. That the fracture occurred before death is certain as embalming resins covered the margins of the break, something that would indicate a compound fracture that broke the skin. People often died in the past from serious breaks. Infection would set in, which could lead to pneumonia, gangrene, or organ failure, and it could happen quickly.

One scenario has Tut being thrown from a chariot, perhaps while hunting. His tomb shows pictures of him riding his chariot in hunts and in battle, although the latter is less likely. Had Tut suffered such an injury, his likelihood of survival would not have been high.
It's entirely possible he died well away from his capitol. In that case, the heat of Egypt would have led to rapid degradation of the corpse, which might well explain the hurried burial. It may even explain why so much resin was poured into the coffin, an attempt, perhaps, to keep the body intact for the afterlife. Or its possible that the embalmers simply did a lousy job. Not all mummifications are equally successful.

Of course, there are those who will still search for conspiracies, no matter how much evidence is presented to the contrary. But, given the results of this scan, it would appear that the Tut murder case should be closed with a verdict of accidental death.

And I'll bet you thought I was going to tie up "curse tablets" with the "curse" of Tutankhamen. Fooled you, didn't I?

Tuesday, December 12, 2006

Ancient Smarts

Genius defies all anticipation. ~ Henri Bergson

One of the hallmarks of modern civilization is a remarkable smugness because of our technological advancement. For decades, the conventional wisdom was that the ancients were clever enough, but the real genius of mankind was to be found in the modern age. Over the last twenty years or so, we had to come to grips with the fact that early civilizations were a damn sight more advanced than we've credited them.

We have found that many of Da Vinci's clever designs actually work. Ironically, when we have trouble making them work, it's because our modern engineers try to “improve” them; when we follow Leonardo faithfully, the results are often remarkable. The more we investigate the engineering of the Romans, the more impressed we become with the sophistication and organization with which they were able to work.

And then there's the lump of bronze found off the island of Antikythera.

The Antikythera Mechanism, or, as it's familiarly known, the Antikytherum, was found in 1902 by sponge divers who were exploring a wreck. It was a lump of corroded bronze that was first thought to be part of a statue, but a closer examination showed that there was more to this lump than first met the eye.

There were gears, gears with v-shaped teeth. And that was totally unexpected.

The Antikythera Mechanism was dated to around 150 BC. There were known to be geared mechanisms dating to that time, but all of them had square gear teeth, which are easier to make. In fact, there were those who felt that there was not sufficient technology available at the time to make precise v-toothed gears. Yet here was a device that clearly had them. Moreover, no one had any idea what the mechanism did.

Since 1902, then, people have been using ever-improving x-ray techniques and scanning methodologies to examine the device. For years, all they've learned is that it's even more complex than originally thought. Writing was found on some of the parts which hinted at possible explanations. More gears were discovered. Finally, enough information was available to take a shot at building one.

Michael Wright was one of those who took the shot, demonstrating that with sufficient time, patience, and skill, the gears could be manufactured with the precision seen in the actual device. When he was done, he was sure he knew what it was: A planetarium.

According to Mr. Wright, the Antikytherum could show the positions of the five known planets, but that wasn't a sure thing, because not all the gears in the original mechanism were available. He had to make assumptions about connecting gears. Now a new analysis has come up with another view.

An Anglo-Greek team, using the latest scanning techniques, has reported that the Antikythera Mechanism was an eclipse calculator. But even they are hedging their bets, because there is writing on the device that says “Mercury” and “Venus”, so at least two planets were being followed, perhaps to study their retrograde motion. The presence of these two planets gives Mr. Wright hope that his interpretation may still be part of the device's use.

So, in 150 BC, we have an analog computer being made to calculate eclipses and possibly planetary positions, a mere 2000 years before any such tool was available to the modern world. Not bad for a bunch of philosophers.

But, if you want to go back, say 5000 years, you'll find something that is almost as amazing as the Antikytherum. Michael Barsoum of Drexel University, and a native of Egypt, has shown that the great pyramids at Giza still have surprises to spring on us. It seems that the ancient Egyptians were not only great engineers and planners, they were pretty fair materials engineers and chemists. It seems that some of the key elements of the pyramids were concrete blocks, not solid limestone. Particularly, the inner and outer casing and the upper blocks were cast in place using a limestone concrete.

That will dent some cherished beliefs of those who have theorized about the construction of these monuments. If the Egyptians were able to cast blocks in place, then some of the problems concerning the ramps needed to haul blocks up to the top of the structures would no longer be so troubling.

There's plenty of evidence to suggest the presence of ramps used in building the pyramids, but how the highest points of the pyramids were reached was always unclear. Did they have one immensely long ramp, or did they wind the ramp around the outside of the structures? Or did they use some sort of combination? Now it seems, according to Mr. Barsoum's peer-reviewed paper, that they found a better way.

Not only does this idea deal eliminate the need to transport large block to very high places, it also explains how the apparent precision of construction could be maintained. With the ability to cast blocks, cumulative imperfections could be overcome by pouring “corrective” blocks as needed or by using the cement to level areas as required.

But here's the really good part. The cement used by the Egyptians has lasted 5000 years. Modern Portland cement, the most commonly used variety today, has a life of 150 years. Now Portland has its own advantages, I'm sure, probably in strenght. But there are many applications where the cement of the pyramids would work as well. If a modern counterpart of the Egyptian compound was used today, it would reduce cement-related pollution (Portland cement releases carbon dioxide) by 90% and wildly outlast the current materials. Not bad for a bunch of ancient tomb-builders.

We have so much to learn.

Thursday, December 07, 2006

Debating Chixulub

A theory is better than its explanation ~ H. P. Woodward

Sixty-five million years ago, the dinosaurs shuffled off this mortal coil, and it's generally agreed on what dispatched them. The creatures appear to have been in decline, most likely due to climatic changes, possibly aggravated by huge lava eruptions that formed the Deccan Traps. Then, as if things weren't bad enough, a meteor came crashing down and finished them off.

Now, one version of the meteor's effects is that the entire planet caught fire, burning all the vegetation and all the dinosaurs who didn't have asbestos feathers, followed by a long-term winter caused by all the debris thrown into the air, which killed off all the vegetation (again) which caused the remaining dinosaurs to starve to death. This is the “dumb version” model. I've written before about this extreme description and how silly it is.

A more reasonable explanation is that the dinosaurs, as said were in decline. A meteor whacks the planet, causing huge amounts of damage on the continent where it impacted. It further throws tons of debris into the air, probably generating a prolonged period of cold which would have depleted the vegetation stocks. This would have probably caused the remaining herbivores to bite the dust. With the plant-eaters gone, the meat-eaters would have been very hard up for food and would undoubtedly gone to that big Cretaceous Park in the sky.

Of course, it would be nice if there was a crater to find that dated to around the time of the dinosaurs' demise, but we've got a reasonably big planet which is geologically active and has around 75% of its surface hidden under water. Not finding a crater would not mean that there was no meteor. Even without the hole in the ground, it's clear some sort of intervention from outer space occurred, because in the geological record at the point at which the dinosaur fossils disappear (known as the K-T boundary), there is a thin, dark, iridium-rich layer, and iridium is not common on Earth. It's most likely source would be from a significant meteor impact.

Despite the odds, a few years ago a crater was found off the Yucatan peninsula that was created 65 million years ago. The crater, dubbed Chixulub, was formed by a huge rock and would have readily accounted for the iridium layer. Bingo, say the scientists. The “smoking gun” has been found.

Initially, theorists laid the bulk of the blame for the mass extinction on the Chixulub event. As time has gone on, the other factors mentioned above have been recognized as precursors that would have made an impact event all the more devastating to the dinosaurs. Generally with few exceptions, paleontologists seem to have accepted the scenario of climate change (probably influenced by the Deccan eruptions) punctuated by the Chixulub impact as ringing down the dinosaur epoch.

Then along comes Gerta Keller from Princeton. The article I mentioned above was partly inspired by a program on the Science Channel (I think it was) that was pushing Ms. Keller's theory, which, to cut to the chase, is that Chixulub was not the cause of the extinction event. After generating a fair amount of misinformation, the program revealed that Ms. Keller thought another meteor was responsible. Well, she's mulled it over a bit, and now she's decided that there were a number of meteors of which Chixulub was only the first, according to this. In addition, the Deccan traps played a part, and the actual killer meteor may have landed where the traps were.

Thus, since last spring, when she was on TV, she's added more meteors, but she still has as her main goal the discrediting of Chixulub as the cause. In fact, that seems to be the only reason for her research. It was what she set out to prove, and by golly, she found evidence, at least in her mind, that proves it. Unfortunately for Ms. Keller, others have evidence that says otherwise.

In the TV program, in my opinion, most of her “proofs” were reasonably refuted, so I was a bit surprised to see her releasing a paper so long after the original report of her theory. However, she evidently did some reworking and gathered additional data. Now someone else has gathered even more data.

A study lead by Ken MacLeod of the University of Missouri, Columbia, investigated more core samples, this time along the northeast coast of South America. You can read the article for the details, but, basically, they indicate no evidence of another impact beyond that of Chixulub.

Ms. Keller reacted by saying that the core samples must have been “rearranged” or have sections “missing.” She describes the results as “rather hyper-inflated.” In other words, her basic response is, “Is not! Is not!”

Essentially, that was her response to criticisms of her theory on the TV program, where she said those who disagreed simply had too much investment in the Chixulub theory to let it go. Rather than respond to the criticisms, she merely dismisses them as professional churlishness.
Which is pretty lame.

I can't say categorically that she's wrong because I don't have the expertise to evaluate the evidence myself. I will say that every refutation of her theory I've seen makes sense. Ms. Keller's responses sound weak by comparison. Much of the basis of her theory lies in analyzing sediments that were thrown up by the impact of the Chixulub meteor, which are a hodgepodge of layers folded up and over one another. And, frankly, it seems that she approached those sediments with the idea of discrediting existing theories, not with the attitude of investigating with an open mind.

Ms. Keller may be on to something, but I am always suspicious of grandiose announcements “disproving” accepted theories. The goal of science is discovery, not disproving things. Einstein did not set out to disprove Newton's view of gravity, rather he expanded on it. Darwin did not set out to disprove Biblical creation; he sought to understand how we and the other creatures of the planet got to be the way we are. In investigating the universe around us, scientists often replace old theories aside; it's what scientific investigation is all about. But setting out to invalidate a theory isn't impartial investigation. It's almost like trimming jigsaw puzzle pieces to fit where you want.

You'll still get a picture; it just won't make much sense.

Tuesday, December 05, 2006

Maybe There Aren't Any Planets

To study any subject scientifically one needs a detached attitude which is obviously harder when one's own interests or emotions are involved. ~George Orwell

I figured we wouldn't be hearing much on the subject of defining the term “planet” for some time, once the sound and fury of reaction to the IAU decision died down. Oh, there was a petition, and Owen Gingerich was going to have his own conference to create a definition, presumably based on the one he originally helped create for the IAU. Mr. Gingrich was very upset because he had chaired the committee charged with coming up with a draft definition, which was no great shakes, but at the International Astronomical Union (IAU) session to decide the final definition, a new proposal was put forth and voted in.

Just to catch you up, the original draft definition read like this: A planet is an object that has enough mass to be round, is in orbit around a star, and is itself not a star or a satellite of another planet. There were also sub-categories in the Gingerich proposal, including “plutons”, a term that was already taken by the Geology crowd. It also promoted Charon to a planet, which promised to be confusing at the very least.

The final “approved" definition ran this way: A planet must orbit the sun; it must be massive enough for its gravity to force it to take on a nearly round shape; and it must have cleared the neighborhood of its orbit of other objects. This verbiage was deemed to have dropped the planetary roll call to 8, although a technical reading of the “clearing the neighborhood” bit could have disqualified Earth and Jupiter, and possibly Mars and Neptune, as well.

I call that a problematic definition, only because I'm using polite words here.

After all the fuss, everything seems to have quieted down rather abruptly. The Gingerich conference hasn't generated any news that I've seen, so I'm not even sure it's going to happen. Meanwhile, the IAU meets again in 2009, when it's presumed they will take up the issue again to try to regain some sense of authority in astronomical matters.

Robert Roy Britt over at Space.com has written rather boldly that there will never be a solid astronomical definition of the term “planet.” I find that disquieting in some ways, but he may have a point. Basically, there's a lot of stuff wandering around in the universe. There are stars, comets, large round gaseous things that have never ignited that are called brown dwarfs or planets (based vaguely on size), rocky round things that are either called planets or moons (depending on what they orbit), smaller round rocky things called dwarf planets (currently), ice round things called ice dwarfs (currently), and lumpy littler things called variously asteroids, Kuiper Belt objects, near-Earth objects, or moons (depending on where they happen to be). As Geoff Marcy says in the article, “Categorizing a thing does not magically add insight.”

True as far as it goes, but categorizing things does force us to attempt to pin down the properties of that thing. That's where the definition of an object comes in. By putting something into the “comet” category, say, we pretty much identify it as a member of a class of things that have a lot of ice and appear to be fairly loosely put together, which put off tails as they approach the Sun because the ices begin to melt and spew out of the comet.

But even comets are problematic. We've had a close look at a few of these interesting things, including crashing a probe into one. One of the Deep Impact scientists put it baldly when he pointed out that, so far, no two comets have been the same. So even something as well-known as a comet is still an unknown quantity in many ways.

Do we need a new definition of comets? Probably not, but we might ultimately need some subdivisions, such as rocky comets, sandy comets, and ice-predominant comets.

So what's wrong with subdivisions of planets? Not a thing, as I pointed out in earlier articles (see links below). What's wrong is creating ill-defined boundaries that tell us nothing about the objects. Lumping Pluto and Ceres into the same group (dwarf planets) is like lumping a dump truck and a boat together. The truck and the boat are both “vehicles” that carry passengers and cargo, but you need a finer grading to actually be able to tell what the major properties of both are. For example, dump trucks don't float worth a darn. That's important if you're trying to decide which one to take to the lake.

That's what is wrong with the IAU's definition. What was wrong with Gingerich's approach was that the overall category of “planet” was that it danced around the question, creating all sorts of ill-defined subcategories that still didn't tell you what would float and what wouldn't.

The exotic objects we're finding orbiting distant stars are just adding to the confusion.

I'm not enough of a scientist to come up with a definitive answer to the question of describing what constitutes a planet or what subcategories make sense. I think, though, that somehow the subdivisions should “add up” to the whole. That is, things like dwarf planets, ice dwarf, asteroids, and Kuiper Belt objects have a place in the evolution of the Solar System. Any set of definitions should not only separate these and other objects into groups, but they should also show how they are interrelated. Nothing I've seen from Mr. Gingerich or the IAU or anyone else seems to address this.

It's too easy to fob off the problem by saying we'll never come up with a good definition or, worse, saying we don't need a good definition. Science is not about taking the easy way out. It's time for astronomers to get their heads on straight and deal with the issue.

To borrow from Bette Davis, Science ain't for sissies.

Some earlier explorations into the subject:
Devaluing Pluto
Dwarfing Pluto
Pluto-nium

Plutonics