Monthly Archives: August 2006

Watch a Spacecraft Crash Into the Moon, LIVE!

Quick! Get a telescope!

The ESA’s SMART-1 spacecraft has run out of fuel after a successful 2 year mission to test new spacecraft technology and study the moon. It is now scheduled to make its own tiny crater on the evening of this coming Saturday September second as it slams into the Lunar surface at a speed of 7,200 kilometers-per-hour. The resultant flash is only likely to last for 20 milliseconds or so, but it may very well be visible, particularly if the dust plume rises high enough to pass outside of the Moon’s shadow into direct sunlight.

The nominal impact is predicted to occur at 5:41:44 UT (Universal Time) which is the same as 10:41 pm PDT. There is always the possibility that the space vehicle will auger in on either the prior (during daylight, and so invisible) or successive orbits (visible very early the next morning).
The tiny red circle depicts the predicted point of impact.

All sorts of interesting science surrounds the mission, but the parts that interest me the most are the technologies used to get the spacecraft to the moon. I am always awed by the incredible precision of our understanding of gravitational trajectories. Check out the planned orbital path that begins with a spiral around Earth with an increasing radius up until it hits a critical stability point and is suddenly transferred to an orbit around the Moon.

One other particularly interesting aspect of the mission is that SMART-1’s primary propulsion system hearkens to Star Wars (the movie) technology. Remember the Galactic Empire’s grey and black T.I.E fighters? Well, T.I.E stands for Twin Ion Engine. SMART-1 traveled the full distance and maneuvered for two years on a Xenon Ion Engine rather than a traditional rocket thruster.

Here is a close-up CAD rendering of the business end of the ion engine. In contrast to a traditional rocket which directs a chemical explosion out of a nozzle to generate thrust, the ion engine strips electrons from Xenon gas, and then uses an electrostatic gun (a high-tech cousin to the one in your tube TV) to accelerate the ions out the back of the craft. While the volume of ionized gas is much smaller than what a chemical rocket would expel, the velocity of the ejected matter is over ten times greater, and there is much less wasted heat and energy. So while the thrust per second is lower, the total thrust can be many times greater for the long-burning ion engine.

(Images courtesy of the ESA.)


Filed under Astronomy, Technology

Help Fight Math Anxiety

I was browsing an interesting post on Jennifer’s Cocktail Party Physics blog the other day when I stumbled on a mini flame-war about a topic dear to my heart. The original post was about a call from for book proposals to help inspire women in science.

The flamers were arguing about whether something that is hard and potentially frustrating can be fun in the context science education, and whether it was the off-putting general difficulty of science that was the problem. I couldn’t resist, so I donned my asbestos boxers and joined the fray.

Ultimately, I felt the argument was about whether people can be taught to find satisfaction in accomplishing something difficult. Here is my post, reproduced here:

One of the biggest barriers I have had to surmount across my years in academia as both science student and teacher is frustration. One of the biggest and most important frustrations has been that of failing to immediately comprehend something.

Different people respond differently to frustration. Some give up and try something else that is perhaps a little less challenging. Others, who are more comfortable remaining in that frustrating state of not-quite-understanding might persist and continue to work on their problem at hand. I am completely convinced that “Math Anxiety” is simply an inability to withstand the frustration of NOT KNOWING something long enough to actually learn it. (Note that this can be either willful or subconscious, but I have had great success in surmounting this particular claim.).

For some, the prospect of that anticipated spark of inspiration or delight that comes from persevering to the point of enlightenment drives them through the uncomfortable uncertainty period. Over time, students learn to be more comfortable and less bothered by NOT KNOWING, and can progress through harder and longer problems as their tolerance and comfort increase. Ultimately, people can learn to anticipate the challenge and revel in the idea that if they can just concentrate long enough, they are sure to eventually learn something and eventually delight in the whole process start-to-finish.

I happen to believe this is NOT an innate ability. It is a learned skill. If there is no properly self-aware teacher available to guide and settle the student through the early frustrations, and the educational environment fails to foster the mental discipline or world-view of intellectual reward through calm persistence, we end up with people who equate “hard” with suffering, who give up on ever achieving profound and potentially life-changing realizations, and who will never know the real joy of figuring out complex and interesting things.

Our schools need more teachers who understand this sort of thing.

So help fight math anxiety. Help people relax and enjoy not knowing. Help people accomplish ever-more-difficult goals.

Anyone else out there have a good story about overcoming math anxiety?


Filed under Education, Math

Science Under Attack: The Big Bang

I have a theory.

Well okay, it’s not really a theory in the scientific sense of the word. I certainly haven’t met that standard of having assembled an overwhelming body of physical data and supporting experimental results to the point that there is no reasonable doubt of its validity.

I’m talking about a theory in the simple every-day layman’s sense of the word. As in, “I have a theory as to why the water isn’t draining from my toilet; it must be due to that large plastic dinosaur my four-year-old was teaching to swim yesterday.”

My theory is that somehow, the Republican Party has run into a serious problem that they fail to even recognize. Their decision to seize political control of a broad range of agencies who depend on informed scientific and technical support has required that they replace many people who have the actual technical knowledge to perform their duties, but are unfortunately encumbered by “subversive” political views with appointees who can toe the party line, but just don’t have the knowledge, training, or experience necessary to make incredibly important decisions.

The problem’s that have arisen from this unfortunate position are now too numerous to list in a simple blog post while still preserving time for my day job. They range from politically motivated funding decisions which are effectively shutting down critical programs (EPA and Global Warming, NSF and Stem Cells, NASA and its entire Earth Environment mission complement) to redirection of funding from FEMA programs intended to protecting the country from extreme natural disasters towards provably less likely and less damaging terrorism defense to the direct detriment of everyone near the Louisiana and Mississippi coast line. Talk about an example of worrying about the wrong thing. Just look at the statistics on deaths, damages, insurance claims, and refugees; there is simply no comparison of scale, yet the misdirected flow of dollars persists.

Other more alarming direct evidence in Iraq is similarly ignored. Recall the retired Generals who called for more troops, and the administrations longstanding insistence that no further troop deployments were necessary? I would say the recent diminution in Bagdad violence by more than half within one week of bolstered deployments puts the lie to the administration’s original strategy. Imagine if we could have had the additional strength there from the beginning. Again, the politics had won over the physical evidence until there was just no possible way to further deny reality. But things had to get pretty damn bad before the undeniable realization set in. What do we do when our country’s technological and economic future begins to follow a similar path? I believe we have already set foot on that road to disaster and desperately need to find another way.

Fortunately, I believe that while much of the damage will take some time and concerted effort to rectify, these poor choices can be remedied rather directly when a new administration comes into office. But I believe there is some longer lasting damage that may result from a change in “the political game” that this administration pioneered. More so than any other administration in history, the Bush administration placed decided in favor of politically, morally, and religiously motivated policies and against what that national science community had determined were the prevalent theories of how the world was actually changing. They have repeatedly chosen to make decisions based on their faith in how the world should be, rather than how physical evidence and theories showed the world to most likely be. But worse than the immediate damage of this short-sighted job and money shuffling, they have set a precedent that it is okay to place religiously or politically oriented directors to “manage” what and how science and technology is published and presented, or even accessible to decision makers and the public. This places the entire technological foundation which elevated the US above Europe, Asia, and the Middle East at risk, not just from this administration, but other later administrations as well that follow suit and employ similar tactics to forward their respective political agendas.

Part of my theory rest on the fact that I don’t think most politicians, political appointees (or perhaps the general public) even understand the definition of the word “theory” in the scientific sense, and therefore misapply the layman’s usage. When a scientist tries to explain the theory of evolution to a proponent of creationism or Intelligent Design (someone who typically has little or no scientific or technical education whatsoever) the listener mistakenly hears the softer “theory” and can be easily mislead to a belief that there is some controversy or doubt, when there really is no doubt whatsoever.

A rather amusing/disturbing event which highlighted this very issue showed that even the scientifically inclined could fall into the trap of misused “theory” definitions. Most of you are probably aware of the incident in which the NASA climatologist James Hansen’s research in global warming and greenhouse gas emissions was censored by the Presidential Appointee. The New York Times article that broke the story created a mild sensation and ultimately resulted in a retraction and new censorship policy announcements. Until last weekend, I had read many of the ancillary news reports, but never the originating article itself.

When I finally picked it up and read behind the fold, I came across this gem from the very same 24 year-old former Bush campaign intern that tried to censor Hansen: (Note my added emphasis did not exist in the original.)

In October, for example, George Deutsch, a presidential appointee in NASA headquarters, told a Web designer working for the agency to add the word “theory” after every mention of the Big Bang, according to an e-mail message from Mr. Deutsch that another NASA employee forwarded to The Times.

The Big Bang memo came from Mr. Deutsch, a 24-year-old presidential appointee in the press office at NASA headquarters whose résumé says he was an intern in the “war room” of the 2004 Bush-Cheney re-election campaign. A 2003 journalism graduate of Texas A&M, he was also the public-affairs officer who sought more control over Dr. Hansen’s public statements.

In October 2005, Mr. Deutsch sent an e-mail message to Flint Wild, a NASA contractor working on a set of Web presentations about Einstein for middle-school students. The message said the word “theory” needed to be added after every mention of the Big Bang.

The Big Bang is “not proven fact; it is opinion,” Mr. Deutsch wrote, adding, “It is not NASA’s place, nor should it be to make a declaration such as this about the existence of the universe that discounts intelligent design by a creator.”

It continued: “This is more than a science issue, it is a religious issue. And I would hate to think that young people would only be getting one-half of this debate from NASA. That would mean we had failed to properly educate the very people who rely on us for factual information the most.”

The fact that this additional censorship caused outrage in the scientific community can certainly be attributed to the religious censorship aspects of the declarations, but the to-do over the specific insertion of the word “theory” was particularly interesting to me. Nobody in the community would deny that the Big Bang is a theory. But it is a theory in the scientific sense in that it has been vetted by an overwhelming body of evidence.

Ironically, Deutsch, the Bush appointee, was trying to degrade and discredit the Big Bang theory by applying the plebian usage, which when written, still complied with how scientists would talk about it themselves. But the scientists knew what he meant to do. “It’s not what you said; it’s how you said it!”

Unfortunately for Deutsch, the evidence for the Big Bang is, quite literally, directly visible before our eyes. All anyone has to do is look up at night. Okay, they have to look carefully with the right telescopes and whatnot. But the fact that due to the finite speed of light, we can effectively and directly see backwards in time more than 14 billion years (by looking farther and farther away) all the way to a point about one minute after the enormous explosion that heralded the beginning of our universe as we know it, is one of the most profound and well-established scientific truths. It is an excellent theory in the strongest sense of the word.

Now all we have to do is properly educate the general public on the correct usage and definition of “theory” as we are using it scientifically to describe Evolution and The Big Bang and whatnot, and hope that people stop trying to cram political and religious agendas into gaps they mistakenly perceive in theories that are really beyond question.

We’ve managed to get most people to agree with the theories that the Earth isn’t the center of the solar system, or the Milky Way Galaxy, or even the Universe. And we’re now pretty unanimous on the theory that the Earth is not flat. Evolution and the Big Bang are in the same territory. All we need is a little more education to make that clear to more people.

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Filed under Astronomy, Politics, Science

National Science Foundation: Science is Hard

From the Onion. It must be true.

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Filed under Humor, Science

The Best Electronics "Toy" EVER!

Just yesterday I stumbled across a treasured bit of history while cleaning out the garage. It was a brochure I had picked up at the 1989 National Science Teacher’s convention in Atlanta. (That tells you the archeological depths plumbed in my latest foray) Despite the fact that I had seen neither hide nor hair of them for the last seventeen years, it turns out they still exist. I was overjoyed to reconnect with the small German company via Google and discover that their line of electronics kits are still available and have even expanded in number.

I have always felt that there has been a large, longstanding, and gaping hole in today’s educational system where electronics should be. It seems almost criminal to me that most children are never really introduced to the technology that has become the very foundation of modern society, telecommunications, computing, networking, media, and entertainment industries. Those who are introduced, rarely see a circuit more complicated than a battery and a light or motor until their undergraduate days. And by that time, the ranks of the interested have been so thinned that we have lost a majority of the potential audience and ranks of latent scientists and engineers.

There have certainly been significant barriers to administering an introductory electronics program to elementary and high school students, ranging from the complexity of interconnecting ever shrinking parts of ever increasing complexity to the hazards of extremely hot soldering irons in tiny hands. But these are functional barriers that tend to mask rather simple and fundamental concepts that could otherwise be approachable at a surprisingly young age. And while lamenting the situation, I had never managed to discover a way to practically surmount these barriers until I found Lectron, GMBH.

The Lectron kits are a wonder of fine German design and engineering unsurpassed in the educational materials market. (They are also pretty pricey, but worth every penny.) Each kit includes an extensive set of electronic components, each of which is individually packaged in a sturdy Lego-like plastic block with magnetized contacts and the industry-standard symbol for the part stenciled on the top face. The steel back-plate can be used as a ground plane to which the magnetized circuit blocks stick, and the process of building circuits is literally reduced to playing with blocks that naturally stick together.

The instructional and guide books are wonders of inspiration with hordes of example circuits. And while a little German reading skill could be helpful, assembly is just so darn simple that you don’t really need more than the example pictures. Any child that can build something with Legos can now build ever more complex electronic circuits with no other training or materials. They can build ANYTHING! (assuming you buy them the deluxe kit with enough pieces!) It comes complete with batteries, meters, resistors, capacitors, transistors, interconnect, LEDs, motors, switches, buttons, solar cells…damn near anything you can imagine.

Check out the range of circuits from a few of their example books:

A simple circuit to light an LED with two batteries.
A simple voltage divider with a meter

A small AM radio transmitter.

Digital logic circuitry.

A simple FM radio receiver.

Lectron pitches the intro kits as appropriate for children ages of 9 and over, but I suspect the simpler circuits and easy block assembly could be accessible starting at ages 5 and 6. In fact, I am ordering a kit for my four-year-old today, and if she doesn’t like it yet, my wife and I will play with it until she is ready.

As for schools, I should think every school in America and eventually the entire country’s economy could benefit strongly from having a dozen of these kits lying around for students to play with instead of shooting spit balls at each other. I might even be convinced to donate a few of them to worthy causes.


Filed under Education, Technology

Study Reports Teacher’s Gender Affects Learning

In the late seventies and early eighties when I was diligently avoiding work at my private high school, science, history, languages, art, and drama were co-ed classes, but home-room, English, math and PE classes were single-sex classes. Before long, however, the forces of political correctness, armed with a familiar chant of “separate is NOT equal,” drove the school to fully integrated co-ed classes with PE as the sole remaining hold-out. I remember feeling a pang of loss when I heard the news, but couldn’t really define why.

Oddly enough, the school now finds itself in a position where despite theoretical equal access to high-level science classes, not one single young lady enrolled in last year’s AP Physics class, which saw over thirty young men perform admirably on the AP test at the end of the school year. So access clearly isn’t the only problem.

In 1989, when I found myself a teacher at a completely co-ed public high school in southern California, I ultimately concluded that the single biggest distraction in the classroom was the opposite sex, and I would have welcomed the idea of teaching two separate physics classes, one to the boys and one to the girls. I struggled to reach both the young men and the women in the class, and found myself half-way through the first semester with the women’s grades starting to slip en-mass. I spent a couple of months trying to come up with different ways of reaching and inspiring the young ladies to no avail. The average girl’s GPA had slipped a whopping 9 points lower than the average boy’s grade by the second month of the final semester. By that time, I was loosing quite a lot of sleep over the issue.

Thankfully, I made a breakthrough when the class was studying electrostatics and simple circuits. Three of my best female students had teamed up to build, test and debug some of the simple battery-resistor-capacitor-transistor circuits I had designed for the class. halfway through the period one of them came to me and said, “Mr. Alvelda, I think we’ve put the circuit together properly but it just doesn’t seem to work.”

When I joined them at their lab bench to check their progress, I found some of the most meticulous and carefully constructed prototype circuitry I have ever seen to this day. But curiously, despite our classroom conversation about conductors and insulators, the young ladies had failed to strip the insulation off the ends of the interconnecting wires. My jaw was hanging open; it had never even occurred to me that someone might reach their teenage years without having assembled an electrical circuit, wire stripping and all. And I had never mentioned the critical step in the entire lab setup.

Of course, when I gently reminded the young ladies of our insulator/conductor discussions, and showed them how the wires were manufactured to allow connections only where you want them while preventing electrical shorts elsewhere, they caught on in a flash and had the circuit working flawlessly in the span of a few minutes.

That moment clearly illustrated to me that all of my assumptions about what kids should have know by the time they reached my class were colored by my own experience, with a father who had me building full-blown radios and computers by the time I was twelve. I had been speaking with a vocabulary and set of experiences much more in common with the young men, and failing to reach the women who did not have similar backgrounds. So I undertook a monumental effort to completely revise my entire Physics curriculum so that it assumed no prior knowledge whatsoever.

Within thirty days, the women’s grades started to recover, and by the end of the school year they ultimately surpassed the men’s grades due largely to a slightly more mature and disciplined approach to studying. I wondered to what extent other teachers have had similar experiences.


From my own personal teaching experience, I wasn’t surprised to see the results of this controversial new study scheduled to appear today in “Education Next,” a quarterly journal published by the Hoover Institution. Thomas Dee, an Associate Professor of Economics at Swarthmore College, and a visiting scholar at Stanford University, has studied the effect of teacher gender on education to conclude that girls learn more from women and boys learn more from men.

Dee examined the performance of nearly 25,000 eighth-graders, the stage of development at which gender gaps in performance begin to arise. He found that with a female teacher, girls performed better (and boys performed worse) in science, social studies, and English, than if the teacher were male.

The effect on students attitude was also measurable. “In a class taught by a man, girls were more likely to say the subject
was not useful for their future. They were less likely to look forward
to the class or to ask questions. With a female teacher, boys were more likely to be seen as
disruptive. Girls were less likely to be considered inattentive or

While obviously controversial, the study is consistent with the findings of the Third International Mathematics and Science Study [TIMSS]
that found, among other things, that the percentage of a country’s 12th grade boys who comprehend probability and statistics increases 1% for each 2% increase in that country’s male teachers.

With women comprising roughly 80% of the public school teaching force, and high-level math and physics classes skewed heavily towards male teachers, this is clearly an issue worth looking into.

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Static Images That Play With Your Rods (In Your Retina)

Believe it or not, this image is not actually animated. The effect you see is the result of the spatial patterns in the image interacting with the interconnected patterns of the photosensitive neurons in your Retina (of which, Rods and Cones figure prominently). Pretty trippy huh?

And more from Akiyoshi’s illusion Page :

If for some reason, you don’t notice any odd effects when looking at these images, note that they tend to work best at their full resolution. So just hop on over to Akiyoshi’s site through the link above to check them out in all their glory.

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The REAL House Advantage

Or “What the Casinos REALLY Don’t want you to know.”

A friend of mine just popped into my office to let me know he was headed to Vegas for the weekend. He flashed that standard rueful “I’m going to Vegas” smile, while I tried share his enjoyment and keep my sigh internal. Most of you who know me are probably already aware that I am not all that excited about gambling in general. I would even go so far as to say that I am pretty solidly against both commercial and government-sponsored gambling.

The reason is simple. I just happen to know enough math to understand that the way these systems are set up is a loosing proposition for the gambler. Big time. My major beef is that whoever is running the game has a very strong incentive to make sure that the customers understand as little as possible about their real chances, and all of the marketing, lighting, sounds with victory and silence for defeat, air conditioning with piped-in oxygen, readily available alcohol, lack of clocks or windows, EVERY little detail of these establishments is set up to purposefully mislead the innumerate into unwise continued gambling until they have lost all their money. And as private companies, they never are in a position where they must disclose exactly how much money they are making and thereby expose their deceit.

And they are making a LOT of money. If I were to ask, “well, exactly how much money do you think they are making,” most people who thought about it for a bit would likely head for a discussion around the odds of each specific game, and the small house advantage, such as 5.26% in roulette, and how with the right systems, or counting techniques, you can get pretty close to evening the odds. If that were all there was to it, I might even head for the tables more often. Sadly, though, there is another detail you need to know.

I am here to tell you that the REAL house advantage is MUCH bigger than that. Besides the numerical advantage of slightly stacked odds, the casinos have an even bigger lever. They have effectively infinitely deep pockets compared to any individual gambler, and this turns out to be an staggering advantage. If you combine the relative purse sizes with the fact that those house odds apply PER BET, rather than in comparison to your purse size, the story starts to look a lot bleaker for the gambler.

Any discussion of making or loosing money based on the house odds would only really be valid if you gambled for an infinite amount of time. Remember that a fair game is random; you will be up some of the time, and down some of the time in a random walk, trending in the long-run of many many trials towards whatever the house odds happen to be.

But with a finite pocketbook, there is one condition that forces you to stop (when you run out of cash or credit) even when you might otherwise recover later were you able to continue. So with random walk excursion upwards, you can keep playing, but with any excursion downward which exceeds your purse, you are forced to stop, and at that point, the casino keeps ALL OF YOUR MONEY, not just 5.26%. Unsurprisingly, most players keep betting while they have money, and stop when they run out. Some players, of course, manage to walk away while they are ahead, but they are the exception, not the rule.

A simple thought experiment, that I first saw articulated in the book “Statistics Hacks,” involving 1,000 gamblers (to make the math easy) is revealing.

Let’s assume that each of 1,000 gamblers starts with a $100 purse and plans to spend 4 hours gambling in an evening. If we assume the house edge is 5.26% as with roulette, and we track a conservative bunch of gamblers that on average place $100 worth of bets per hour:

At those odds, about 100 people will run out of money per hour and be forced to stop. After four hours, about 600 people would still be playing and have an average purse of about $78.96 each, which would total $47,376. The casino will have accumulated $52,624, which amounts to about a 52.62% take. That’s a bit steeper than the published house odds, eh? And for those 400 people who lost, they didn’t loose 5.26% of their stake, they lost ALL OF IT. And somehow, I have yet to see any casino really articulate this effect.

Now how many people do you suppose would gamble to begin with if they knew the odds were REALLY stacked against them by 41% when you account for limited purse size, or perhaps walk by a posted warning that “52% of you people entering this casino should expect to loose all your money and the rest of you will likely loose about 20% on average?”

It is exactly this willful deceit that pits me against the gambling establishment. And while one might certainly make the argument that it is a personal responsibility to be aware of the risks of gambling and temper spending, most people in the US have never taken a statistics course. And with a strongly vested interest in maintaining and even promoting the ignorance and encouraging irresponsible behavior, casinos and even state governments that run the lotteries, have demonstrably failed to guard the public interest in this regard for quite some time. While you ponder the morality of this issue, reflect on the personal responsibility issues surrounding the health effects of smoking, and how an entire industry mislead their largely biologically uneducated market to ensure continued profits. It doesn’t seem all that different to me.

If you doubt this sort of analysis, try and make a Monte-Carlo simulator which follows these more realistic, finite rules. And if you aren’t all that inclined to go to that effort, all you really need to do is take a closer look at how many big and lavish casinos have become models of ostentation. That’s your money they are using. If you want to have any real chance of preserving winnings, your best bet is to just pick a time that you will stop gambling whether you are up or down, and stick to it. That way over time, you might at least begin to approach the house odds and take a while to loose all your money.

Good luck!

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Filed under Humor, Math

Aurorae From Space

Why the aurorae shine
Check out this photo from the ESA’s Cluster mission. High Cool.

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Fickle Astronomers Can’t Decide Pluto’s Fate

It would seem that I spoke too soon last week when I welcomed the prospect of our new planetary neighbors. In a stunning turn-around, the International Astronomers Union reversed their previous position of adding three new planets to our solar system. Instead, the IAU came to the rather difficult decision of stripping Pluto of it’s planetary status.

The decision was ultimately driven by technical advances that have allowed us to look deeper into space, and to more accurately determine the sizes of remote objects. “This is all about the advancement of science changing our thinking as we get more information,” said Richard Binzel, professor of Planetary Sciences at MIT, and a member of the planet definition committee.

The New Solar System (BBC)

The IAU scientists agreed that, to be called a planet, a celestial body must:

  1. Be in orbit around a star while not itself being a star.
  2. It must be large enough in mass for its own gravity to pull itself into a nearly spherical shape.
  3. It must have gravitationally swept and cleared the immediate neighborhood of its orbit of other debris.

So Pluto failed their third rule due to its orbital overlap with Neptune. Xena, and Ceres also fail this measure. Even now, though, the publishers haven’t started warming up the presses yet, because the astronomical smack-down continues.

From yahoo: “Pluto Hijacked in Revolt”
By Paul Rincon
Science reporter, BBC News

A fierce backlash has begun against the decision by astronomers to strip Pluto of its status as a planet.

On Thursday, experts approved a definition of a planet that demoted Pluto to a lesser category of object. But the lead scientist on Nasa’s robotic mission to Pluto has lambasted the ruling, calling it “embarrassing”. And the chair of the committee set up to oversee agreement on a definition implied that the vote had effectively been “hijacked”.

The vote took place at the International Astronomical Union’s (IAU) 10-day General Assembly in Prague. The IAU has been the official naming body for astronomy since 1919. Only 424 astronomers who remained in Prague for the last day of the meeting took part.

An initial proposal by the IAU to add three new planets to the Solar System – the asteroid Ceres, Pluto’s moon Charon and the distant world known as 2003 UB313 – met with considerable opposition at the meeting. Days of heated debate followed during which four separate proposals were tabled.

Eventually, the scientists adopted historic guidelines that see Pluto relegated to a secondary category of “dwarf planets”.

Drawing the line

Dr Alan Stern, who leads the US space agency’s New Horizons mission to Pluto and did not vote in Prague, told BBC News: “It’s an awful definition; it’s sloppy science and it would never pass
peer review – for two reasons.

“Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets. It’s as if we declared people not people for some arbitrary reason, like ‘they tend to live in groups’.

“Secondly, the actual definition is even worse, because it’s inconsistent.”

“One of the three criteria for planethood states that a planet must have “cleared the neighbourhood around its orbit”. The largest objects in the Solar System will either aggregate material in their path or fling it out of the way with a gravitational swipe.

Pluto was disqualified because its highly elliptical orbit overlaps with that of Neptune. But Dr Stern pointed out that Earth, Mars, Jupiter and Neptune have also not fully cleared their orbital zones. Earth orbits with 10,000 near-Earth asteroids. Jupiter, meanwhile, is accompanied by
100,000 Trojan asteroids on its orbital path.

“These rocks are all essentially chunks of rubble left over from the formation of the Solar System more than four billion years ago. “If Neptune had cleared its zone, Pluto wouldn’t be there,” he added.

Stern said like-minded astronomers had begun a petition to get Pluto reinstated. Car bumper stickers compelling motorists to “Honk if Pluto is still a planet” have gone on sale over the internet and e-mails circulating about the decision have been describing the IAU as the “Irrelevant Astronomical Union”.

I wonder which Roman gods will triumph?

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