Shallow Thoughts : tags : science

Bogus statistics on drug use among drivers

The "Roadshow" column in yesterday's Merc had some pretty ... odd ... statistics involving marijuana and driving.

It quotes "an NHTSA report" as saying:

contrary to popular belief, marijuana has been found to play a significant role in car accidents across the United States, with as much as 33 percent of drivers arrested at the scene of the accident being positive for marijuana and another 12 percent testing positive for marijuana and cocaine. Every year, 28 percent of drivers in the U.S. will attempt to drive within two hours after ingesting alcohol or illicit drugs. Marijuana is the drug used most often — 70 percent — by drivers who drove after drug use and is a major factor why crashes are the leading cause of death for American young people.

Whoa. Let's play that back again: 45 percent of all drivers arrested at accident scenes (33 plus another 12) test positive for marijuana? Nearly half?

Mr. Roadshow, you don't really believe that number, do you?

I didn't. So I did some searching, looking for the NTHSA source.

When I searched for large portions of the quoted phrase, I didn't find anything from the NHTSA. The Roadshow quote appears to come from an article on friendsdrivesober.org (I'm sure that's an unbiased source). Here's their MS Word file or Google's cached HTML version). The same article is also available as a PDF at prevnet.org and there are lots of other pages making reference to it.

The friendsdrivesober.org article cites "Brookoff, Cook & Mann, 1994; Sonderstrom, Dischinger, Kerns & Trillis, 1995." for the 33% number. There's no citation offered for the "28% will attempt to drive...". They credit "NHTSA, 2000" for "Marijuana is the drug used most often ... by drivers who drove after drug use", but that one's not important because it says nothing about prevalence in accidents, merely that it's used more often than other drugs (no surprise there).

The NHTSA weighs in

Googling on a more general set of terms, I found my way to a October 2000 NHTSA report, Field Test of On-Site Drug Detection Devices. It's a roundup of many different studies, with drug use numbers all over the map, though none larger than the 33% figure and certainly nothing near 45%. That 33% figure is near the bottom:

Brookoff et al. (1994) used on-site testing devices in a study that found a 58% prevalence rate for drugs in subjects arrested for reckless driving (who were not found to be impaired by alcohol). The Brookoff team found that 33% of their sample tested positive for marijuana, 13% for cocaine, or 12% for both. (Because of sampling flaws in the study, these drug test rates should not be interpreted as drug prevalence rates for reckless drivers.) Interestingly, the on-site device (Microline) used by Brookoff and his colleagues generated a significant false positive rate for marijuana when compared to GC/MS results.

The horse's mouth

So what about the original study? I wasn't able to find Dischinger, Kerns & Trillis, but here's Brookoff et al. at the New England Journal of Medicine: Testing Reckless Drivers for Cocaine and Marijuana (cookies required).

A couple of important notes on the study: the figures represent percentage of drivers arrested for "reckless driving that would constitute probable cause to suspect intoxication by drugs", who were not considered to be under the influence of alcohol, and who were suspected of being under the influence of marijuana or cocaine ("all patrol officers were told that they could summon [the testing van] if they stopped a person suspected of driving recklessly under the influence of cocaine or marijuana"). Morover, not all drivers consented to be tested, and the percentages are only for those who were tested.

Seems like a perfectly valid study, as far as it goes (though there's been some mild criticism of the test they used). It's mostly interesting as a study of how marijuana and cocaine use correlate with visible intoxication and sobriety test results. It's not a study of the prevalence of drugs on the road: the NHTSA report is right about that. The numbers it reports are useless in that context.

So the jump from that study to what friendsdrivesober.org and Roadshow implied -- that 45% of people involved in car accidents test positive for marijuana -- is quite a leap, and attributing that leap to the NHTSA seems especially odd since they explicitly say the study shouldn't be used for those purposes.

What really happened here?

So what happened here? Brookoff, Cook, Williams and Mann publish a study on behavior of reckless drivers under the influence of drugs.

NHTSA makes a brief and dismissive reference to it in a long survey paper.

Then friendsdrivesober.org writes an article that references the study but entirely misinterprets the numbers. This study gets picked up and referenced by other sites, out of context.

Then somehow the paragraph from friendsdrivesober.org shows up in Roadshow, attributed to the NHTSA. How did that happen?

If you look at the friendsdrivesober.org article, the paragraph cites Brookoff in its first sentence, then goes on to other unrelated claims, citing an NHTSA study at the end of the paragraph. I suppose it's possible (though hard to understand) that one could miss the first reference, and take the NHTSA reference at the end of the paragraph as the reference for the whole paragraph. That's the best guess I can come up with. Just another example of the game of telephone.

Nobody with any sense thinks it's a good idea to drive under the influence of marijuana or other intoxicants. But bogus statistics don't help make your point. They just cast doubt on everything else you say.

Tags: math, statistics, headlines, science
[ 12:33 Jul 31, 2010    More headlines | permalink to this entry ]

Making "Citizen Science" compelling

I had the opportunity to participate in a focus group on NASA's new "citizen science" project, called Moon Zoo, with a bunch of other fellow lunatics, amateur astronomers and lunar enthusiasts.

Moon Zoo sounds really interesting. Ordinary people will analyze high-resolution photos of the lunar surface: find out how many boulders and craters are there. I hope it will also include more details like crater type and size, rilles and so forth, though that wasn't mentioned. These are all tasks that are easy for a human and hard for a computer: perfect for crowdsourcing. Think Galaxy Zoo for the moon. The resulting data will be used for planning future lunar missions as well as for general lunar science.

It sounds like a great project and I'm excited about it. But I'm not going to write about Moon Zoo today -- it doesn't exist yet (current estimate is mid-March), though there is a preliminary PDF. Instead, I want to talk about some of the great ideas that came out of the focus group.

The primary question: How do we get people -- both amateur astronomers and the general public, people of all ages -- interested in contributing to a citizen science project like Moon Zoo?

Here are some of the key ideas:

Make the data public

This was the most important point, echoed by a lot of participants. Some people felt that many of the existing "citizen science" projects project the attitude "We want something from you, but we're not going to give you anything in return." If you use crowdsourcing to create a dataset, make it available to the crowd.

Opening the data has a lot of advantages:

• People can make "mashups", useful sites that display your data in useful ways or combine it with other data. This can generate more interest in your project and more contributors.
• School groups can work on class projects or science fair projects, probably contributing more data along the way.
• It might help the next generation of scientist get started.
• It shows openness and good faith: witness the recent blow-up over the leaked IPCC emails and the debate over how much climate data has been kept private.

Projects like Wikipedia and Open Street Map, as well as Linux and the rest of the open source movement, show how much an open data model can inspire contributions.

Give credit to individuals and teams

People cited the example of SETI@Home, where teams of contributors can compete to see who's contributed the most. Show rankings for both individuals and groups, so they can track their progress and maybe get a bit competitive with other groups. Highlight groups and individuals who contribute a lot -- maybe even make it a formal competition and offer inexpensive prizes like T-shirts or mugs.

A teenaged panel member had the great suggestion of making buttons that said "I'm a Moon Zookeeper." Little rewards like that don't cost much but can really motivate people.

Offer an offline version

They wanted to hear ideas for publicizing Moon Zoo to groups like our local astronomy clubs.

I mentioned that I've often wanted to spread the word about Galaxy Zoo, but it's entirely a web-based application and when I give talks to clubs or school groups, web access is never an option. (Ironically, the person leading the focus group had planned to demonstrate Galaxy Zoo to us but couldn't get connected to the wi-fi at the Lawrence Hall of Science.)

Projects are so much easier to evangelize if you can download an offline demo.

And not just a demo, either. There should be a way to download a real version, including a small data set. Imagine if you could grab a Moon Zoo pack and do a little classifying whenever you got a few spare minutes -- on the airplane or train, or in a hotel room while traveling.

Important note: this does not mean you should write a separate Windows app for people to download. Keep it HTML, Javascript and cross platform so everyone can run it. Then let people download a local copy of the same web app they run on your site.

Make sure it works on phones and game consoles

Lots of people use smartphones more than they use a desktop computer these days. Make sure the app runs on all the popular smartphones. And lots of kids have access to handheld web-enabled game consoles: you can reach a whole new set of kids by supporting these platforms.

Offer levels of accomplishment, like a game

Lots of people are competitive by nature, and like to feel they're getting better at what they're doing. Play to that: let users advance as they get more experienced, and give them the option of doing harder projects. "I'm up to level 7 in Moon Zoo!"

Use social networking

Facebook. Twitter. Nuff said.

Don't keep results a secret

Quite a few scientific publications have arisen out of Galaxy Zoo -- yet although most of us were familiar with Galaxy Zoo, few of us knew that. Why so secretive? They should be trumpeting achievements like that.

How many times have you volunteered for a survey or study, then wondered for years afterward how the results came out? Researchers never contact the volunteers when the paper is finally published. It's frustrating and demotivating; it makes you not want to volunteer again. Lots of us sign up because we're curious about the science -- but that means we're also curious about the results.

With citizen science projects, this is particularly easy. Set up a mailing list or forum (or both) to discuss results and announce when papers are published. Set up a Twitter account and a Facebook group to announce new papers to anyone who wants to follow. This is the age of Web 2.0, folks -- there's no excuse for not communicating.

I don't know if NASA will listen to our ideas. But I hope they do. Moon Zoo promises to be a terrific project ... and the more of these principles they follow, the more dedicated volunteers they'll get and that will make the project even better.

Tags: science, astronomy, open source, crowdsourcing
[ 19:25 Feb 06, 2010    More science/astro | permalink to this entry ]

Pluto Visits the States

This is a reprinting of an article I wrote for my monthly planet column in the SJAA Ephemeris:

Is Pluto a planet, or not? Maybe you caught the news last month that Illinois, birthplace of Clyde Tombaugh, has declared Pluto a planet. It joins New Mexico, Tombaugh's longtime home, which made a similar declaration two years ago.

When I first heard about the New Mexico resolution, I was told that they had declared that Pluto would be a planet within the state's boundaries. That made me a bit curious: would Pluto even fit inside New Mexico? I looked it up: Pluto has a diameter of 2300km, while New Mexico is about 550km in longitude and a bit more in latitude. Not even close (see Figure 1). Too bad -- I liked the image of Pluto and Charon coming to visit and hang out with friends. Though at Pluto's orbital velocity (it takes it just under 248 years to complete its 18 billion kilometer orbit, meaning an average speed of 23 million km/year or 63,000 km/day) and its current distance of about 32 AU (4.8 billion km), it whould take it about 207 years to get here.

But it turns out that's not what the resolution said anyway. Both states' resolutions said roughly the same thing:

BE IT RESOLVED BY THE LEGISLATURE OF THE STATE OF NEW MEXICO that, as Pluto passes overhead through New Mexico's excellent night skies, it be declared a planet and that March 13, 2007 be declared "Pluto Planet Day" at the legislature.

RESOLVED, BY THE SENATE OF THE NINETY-SIXTH GENERAL ASSEMBLY OF THE STATE OF ILLINOIS, that as Pluto passes overhead through Illinois' night skies, that it be reestablished with full planetary status, and that March 13, 2009 be declared "Pluto Day" in the State of Illinois in honor of the date its discovery was announced in 1930.

So the law applies to anyone (though it's probably not enforceable outside state boundaries) -- but only when Pluto is overhead in New Mexico or Illinois.

But wait -- does Pluto ever actually pass overhead in those states?

New Mexico stretches from 31.2 to about 37 degrees latitude, while Illinois spans 36.9 to 42.4. Right now Pluto is in Sagittarius, with a declination of -17° 41'; there's no way anyone in the US is going to see it directly overhead this year. Worse, it's on its way even farther south. It won't cross into the northern hemisphere until the beginning of 2111. But how far north will it go?

My first thought was to add Pluto's inclination -- 17.15 degrees, very high compared to other planets -- to the 23 degrees of the ecliptic to get 40.4°. Way far north -- no problem in either state! But unfortunately it's not as simple as that.

It turns out that when Pluto gets to its maximum north inclination, it's in Bootes (bet you didn't know Bootes was a constellation of the zodiac, did you? It's that 17° inclination that puts Pluto just past the Virgo border). That'll happen in February of 2228.

But in the Virgo/Bootes region, the ecliptic is 8° south of the equator, not 23° north. So we don't get to add 23 and 17; in fact, Pluto's declination will only be about 7.3° north. That's no help!

To find the time when Pluto gets as far north as it's going to get, you have to combine the declination of the ecliptic and the angle of Pluto above the ecliptic. The online JPL HORIZONS simulator is very helpful for running data like that over long periods -- much easier than plugging dates into a planetarium program. HORIZONS told me that Pluto's maximum northern declination, 23.5°, will happen in spring of 2193.

Unfortunately, 23.5° isn't far enough north to be overhead even from Las Cruces, NM. So Pluto, sadly, will never be overhead from either New Mexico or Illinois, and thus by the text of the two measures, it will never be a planet.

With that in mind, I'm asking you to support my campaign to persuade the governments of Ecuador and Hawaii to pass resolutions similar to the New Mexico and Illinois ones. Please give generously -- and hurry, because we need your support before April 1!

Tags: science, astronomy, pluto, humor, writing
[ 19:09 Apr 01, 2009    More science/astro | permalink to this entry ]

Bright naked-eye comet: 17/P Holmes

I finally got a chance to take a look at Comet 17/P Holmes. I'd been hearing about this bright comet for a couple of days, since it unexpectedly broke up and flared from about 17th magnitude (fainter than most amateur telescopes can pick up even in dark skies) to 2nd magnitude (easily visible to the naked eye from light-polluted cities). It's in Perseus, so only visible from the northern hemisphere, pretty much any time after dark (but it's higher a little later in the evening).

And it's just as bright as advertised. I grabbed my binoculars, used a finder chart posted by one of our local SJAA members, and there it was, bright and obviously fuzzy. Without the binoculars it was still easy to see, and still noticably fuzzy.

So I dragged out the trusty 6" dobsonian, and although it has no visible tail, it has lots of structure. It looked like this:
It has a stellar nucleus, a bright inner area (the coma?) and a much larger, fainter outer halo. There's also a faint star just outside the coma, so it'll be fun (if we continue to get holes in the clouds) to see how fast it moves relative to that star. (Not much motion in the past hour.)

It's nice to have a bright comet in the sky again! Anyone interested in astronomy should check this one out in the next few days -- since it may be in the process of breaking up, there's no telling how long it'll last or what will happen next. Grab some binoculars, or a 'scope if you have one, and take a look.

Tags: science, astronomy
[ 21:51 Oct 28, 2007    More science/astro | permalink to this entry ]

Traffic Science

NPR this morning had a program on speeding. One of the "experts" they brought in was Richard Retting, senior transportation engineer with the IIHS (that's the Insurance Institute for Highway Safety, a group funded by auto insurance companies).

Early on they asked him why speeding was bad. He said there were three reasons. The first two were straightforward: when you're going faster, you (1) travel farther before you can react to something, and (2) take longer to stop. No problem there, and I waited for the third reason, presuming it was going to be kinetic energy.

Well, almost. The third reason, he said, was energy. "Remember that equation E = mc² from high school?"

Wow! If I drive faster than the speed limit, I'm converting my mass into energy? For those who haven't studied physics recently, he was probably confusing Einstein's equation relating energy, mass and the speed of light with Newton's formula for kinetic energy, KE = mv²/2. The host responded incredulously "The speed of light?" but Retting didn't seem to notice, and pressed on: "When you're going faster, your energy is disproportionate and exponential."

Okay, you're talking on the radio and you have a brain-o. I'm sure we've all said silly things when we knew better, like reciting the wrong equation then not noticing the gaffe. But he also seems confused about what "exponential" means, perhaps because of that "exponent" of 2 in the equation. An exponential curve is when you have something like 2^X, not X². Admittedly, the dictionary of "exponential" includes vague definitions like "Pertaining to exponents", and I suppose there is an exponent of 2 involved. But really, folks: kinetic energy increases as the square of speed.

A little later in the program, someone called in to mention studies showing that higher speeds don't necessarily correlate with accidents, and Redding chastised him for doing google searches for studies: "That's not how we do science in this country." Hey, Mr. Retting -- it might pay to be a little more careful with your own science if you're going to be dismiss callers with remarks like that.

Tags: science
[ 17:37 Jun 07, 2007    More science | permalink to this entry ]

The Fibonacci Spiral and the Nautilus

or, don't believe everything you read

I've been working on a short talk on Fibonacci numbers for a friend's math class.

Back when I was in high school, I did a research project on Fibonacci numbers (their use in planning the growth of a city's power stations), and for a while I had to explain the project endlessly, so I thought I remembered pretty well what sorts of visuals I'd need -- some pine cones, maybe some flower petals or branching plants, graphics of the golden ratio and the Fibonacci/ Golden Spiral, and some nice visuals of natural wonders like the chambered nautilus and how that all fits in with the Fibonacci sequence.

I collected my pine cones, took some pictures and made some slides, then it was time to get to work on the golden spirals. I wrote a little GIMP script-fu to generate a Fibonacci spiral and set of boxes, then I went looking for a Chambered Nautilus image on which I could superimpose the spiral, and found a pretty good one by Chris 73 at Wikipedia. I pasted it into GIMP, then pasted my golden spiral on top of it, activated the Scale tool (Keep Aspect Ratio) and started scaling.

And I just couldn't get them to match!

No matter how I scaled or translated the spiral, it just didn't expand at the same rate as the nautilus shell.

So I called up Google Images and tried a few different nautilus images -- with exactly the same result. I just couldn't get my Fibonacci spiral to come close.

Well, this Science News article entitled Sea Shell Spirals says I'm not the only one. In 1999, retired mathematician Clement Falbo measured a series of nautilus shells at San Francisco's California Academy of Sciences, and he found that while they were indeed logarithmic spirals (like the golden spiral), their ratios ranged from about 1.24 to 1.43, with an average ratio of about 1.33 to 1, not even close to the 1.618... ratio of the Golden Spiral. In 2002,John Sharp noticed the same problem (that link doesn't work for me, but maybe you'll have better luck).

As the Science News article points out,

Nonetheless, many accounts still insist that a cross section of nautilus shell shows a growth pattern of chambers governed by the golden ratio.

No kidding! Google on fibonacci nautilus and you'll get a boatload of pages using the chambered nautilus as an illustration of the Fibonacci (or Golden) spiral in nature. It's not just the web, though -- I've been reading about nautili as Fibonacci examples for decades in books and magazines. All these writers just pass on what they've read elsewhere ... just like I did for all those years, never actually measuring a nautilus shell or trying to inscribe a golden spiral on one.

Now do a Google image search for the same terms, and you'll get lots of beautiful pictures of sectioned nautilus shells. You'll also get quite a few pictures of fibonacci spirals. But none of those beautiful pictures will actually have both the nautilus and the spiral in the same image.

And now I know why -- because they don't match!

(Happily, this actually may be a better subject for my talk than the nautilus illustration I'd originally planned. "Don't believe everything you read" is always a good lesson for high schoolers ... and it's just as relevant for us adults as well.)

(Slides from the talk I wrote start here: The Rabbit, the Nautilus and the Pine Cone.)

Tags: science
[ 21:15 Feb 08, 2007    More science | permalink to this entry ]

On the Twelfth Day of Christmas, My True Love Gave to Me ...

At dinner last night, amid the ubiquitous miasma of egregious Christmas music which is inescapable in public places starting in mid November, during "The Twelve Days of Christmas" Dave got a faraway expression in his eyes. My mother asked why, and he explained that he was thinking about the mathematics of the song: how many items of each type have been given by the end, and which items are more numerous?

There are two ways to interpret the song.

On the second day of Christmas, my true love gave to me
Two turtle doves
And a partridge in a pear tree.

So by the second day, you have two turtle doves, and you have the original partridge -- but do you also have a second partridge, as a literal interpretation of the song implies? Or is the song simply repeating all the previous gifts, not implying that they're given again?

Most people seem to assume the latter, but let's take the song literally and assume that on the third day, you get three french hens, plus two more turtle doves (that makes four) and one new partridge (for a total of three).

My first thought was that at time step T, you double what you had in step T-1 (you're getting all the same stuff yet again) and add T for the new gifts. But that's not right: you get a new load of each item (one partridge, two doves, three hens, and so forth) but you don't double all the accumulated extras who are now crowding your back yard. Time to start writing down the sums.

At each time T, the quantity you have of the Jth item is:

	T
NJ,T =	Σ J
	i=J

That's easy: it's just N_J,T = J*T- J*(J-1) (pretend you've given J of the Jth object at each time step; but since you didn't give it before timestep J, subtract all the ones up to timestep J-1).

N_J,T = J * (T - J + 1)

If all you want to know is how many of each item you have at the end (on the 12th day), plug in T-12:

N_J,12 = J * (13 - J)

A quick sanity check: that means you'll have 12 of item 1 (partridges in pear trees), because you've gotten one new one each time, and 12 of item 12 (drummers drumming), which you got in one big noisy box on the last day. Likewise, you'll have 22 each of items 2 (turtle doves, of which you got two every day except the first day) and 11 (pipers piping), which you got on day 11 and again on day 12.

So the curve which interested Dave is an inverted parabola; you get the least number of the first and last gifts, and the largest quantity of the two middle gifts: six geese a'laying and seven swans a'swimming. How many geese and swans do you get in the end? Here's the surprising answer:

N_6,12 = N_7,12 = 6 * 7 = 42

Douglas Adams fans will immediate recognize this as the solution to the ultimate question of Life, the Universe, and Everything. Now you know what the question was!

One last question: how many items, total, of all types will you have by the end of the twelfth day?

Since you already know how many of each item you have, just add them all up:

	12		12		12		12
Ntot =	Σ j * (13-j)	=	Σ (j * 13 - j2)	= 13 *	Σ j	-	Σ j2
	j=1		j=1		j=1		j=1

Fortunately, we know that

A
Σ i	= A (A + 1) / 2
i=1

and

A
Σ i2	= A (A + 1) (2A + 1) / 6
i=1

so we can use those identities to figure out how many total items we'll have:

Ntot	= { 13 * (12 * 13) / 2 } - { 12 * 13 * 25 / 6 }
	= 364

So it turns out that true love packs a present for just about every day of the year into those twelve days!

(And I found an excuse to play with using HTML tables to display equations.)

Tags: science
[ 11:59 Dec 21, 2006    More science | permalink to this entry ]

Mercury Transits and Titan Occultations

Mercury transited the sun today. The weather forecast predicted rain, and indeed, I awoke this morning to a thick overcast which soon turned to drizzle. But miraculously, ten minutes before the start of the transit the sky cleared, and we were able to see the whole thing, all five hours of it (well, we weren't watching for the whole five hours -- the most interesting parts are the beginning and end).

I had plenty of practice with solar observing yesterday, showing the sun to a group of middle school girls as part of an astronomy workshop. This is organized by the AAUW, the same group that runs the annual Tech Trek summer science girls' camps. (The Stanford Tech Trek has a star party, which is how I got involved with this group.) It's the second year I've done the astronomy workshop for them; this year went pretty smoothly and everybody seemed to have a good time observing the sun, simulating moon phases, learning about the Doppler effect and plotting relative distances of the planets on a road map.

But what I really wanted to write about was the amazing video shown by last weekend's SJAA speaker, Dr. Ivan Linscott of Stanford. As one of the team members on the New Horizons mission to Pluto, he was telling us about Pluto's tenuous atmosphere. There isn't a lot of information on Pluto's atmosphere yet, but one of the goals of New Horizons is to take readings as Pluto occults the sun to see how sunlight is refracted through Pluto's atmosphere.

But that's no problem: it turns out we've already done more challenging occultation studies than that. Back in December 2001, Titan occulted a binary star, and researchers using Palomar's Adaptive Optics setup got a spectacular video of the stars being refracted through Titan's atmosphere as the occultation progresses.

This is old news, of course, but most of us hadn't seen it before and everyone was blown away. Remember, this is a video from Earth, of the atmosphere of a moon of Saturn, something most Earth-based telescopes would have trouble even resolving as a disk. Watch the Titan occultation video here.

Tags: science, astronomy
[ 22:38 Nov 08, 2006    More science/astro | permalink to this entry ]

Pluto is too a planet

The BBC had a good article today about the International Astronomical Union vote that demoted Pluto from planet status.

It was fairly obvious that the previous proposal, last week, that defined "planet" as anything big enough that its gravity made it round, was obviously a red herring that nobody was going to take very serious. Fercryinoutloud, it made the asteroid Ceres a planet, as well as Earth's moon (in a few billion years when it gets a bit farther away from us and ceases to be considered a moon).

But apparently there were several other dirty tricks played by the anti-Pluto faction, and IAU members who weren't able to be in the room at the time of the vote are not happy and are spoiling for a rematch. The new definition doesn't make much more sense than the previous one, anyway: it's based on gravitationally sweeping out objects from an orbit, but that also rules out Earth, Mars, Jupiter and Neptune, all of which have non-satellite objects along their orbits.

And of course the public is pretty upset about it for sentimental, non-scientific reasons. Try searching for Pluto or "Save Pluto" on Cafe Press to see the amazing selection of pro-Pluto merchandise you can buy barely a day after the IAU decision. (Personally, I want a Honk if Pluto is still a planet bumper sticker.)

It'll be interesting to see if the decision sticks.

So do I have a viable definition of "planet" which includes Pluto but not Ceres or the various other Kuiper belt objects which are continually being discovered?

Why, no, I don't. But the discussion is purely semantic anyway. Whether we call Pluto a planet doesn't make any difference to planetary science. But it does make a difference to an enormous collection of textbooks, museum exhibits, and other science-for-the-public displays.

Pluto is big enough to have been discovered in 1930, back in the days before computerized robotic telescopes and satellite imaging; it's been considered a planet for 76 years. There's no scientific benefit to changing that, and a lot of social and political reason not to -- especially now with New Horizons headed there to give us our first up-close look at what Pluto actually looks like.

There are two possible bright notes to the Pluto decision. First, Mark Taylor pointed out that it has become much easier to observe all the planets in one night, even with a very small telescope or binoculars.

And second, maybe Christine Lavin will make a new updated version of her song Planet X and go on tour with it.

Tags: science, astronomy
[ 21:56 Aug 25, 2006    More science/astro | permalink to this entry ]

Math Skills

I just got back from the local Safeway, where a one-pound box of sugar cubes costs $1.49.

A two-pound box, same brand, is $3.99.

What a deal!

Even better, the two-pound price is up: it used to be $3.49 a few months ago (no change in the one-pound price).

I guess too many people were jumping on that incredible $3.49 deal, so they had to raise it.

Tags: science, humor
[ 16:25 Jul 26, 2006    More misc | permalink to this entry ]

The Hayward Fault -- Exposed!

Today was opening day for the Hayward fault!

Well, okay, the fault itself has been there a while, but it was opening day for the Hayward Fault: Exposed! exhibit in Fremont. They've dug a trench into the Hayward fault as part of the 1906 San Francisco Earthquake Centennial activities, so people can walk a stairway and stand right in a fault and see what it looks like.

I'm a volunteer docent for the exhibit: one of the people who help answer questions about the fault, the trench, and earthquakes in general, and who also help with details such as setup, safety, and getting people to sign the liability waiver as they enter the exhibit. (My photos and fault facts here.)

Opening day was a bit hectic even aside from the usual opening-day flutters because it was a big day in Fremont Central Park: there was a huge manga festival at the Teen Center right next to the fault trench, complete with live band all day, and over at Lake Elizabeth at the other end of the park was the annual "Splashdown" rubber ducky race.

We expected chaos. But we didn't get it: everything went surprisingly smoothly. We got lots of visitors who were there specifically to see the fault, not just spillover from the other events: apparently it had gotten press on the TV news and several newspapers. There may also have been word of mouth advertising: a surprising number of the visitors I talked to were CERT volunteers or otherwise actively involved in bay area disaster preparedness programs. They were already very well informed about seismic hazards and earthquakes, and eager to see the fault for themselves.

We ended up with about 600 visitors (perhaps a fourth to a third of them teens from the manga festival). Everyone was very well behaved, asked good questions and seemed to appreciate the exhibit. It's lovely to volunteer at exhibits where you spend all your time answering questions, chatting with people and explaining the exhibit, not worrying about policing people and enforcing rules.

(Well, maybe there was a little bit of chaos. The band at the manga festival included karaoke. It's not every day that one gets the opportunity to try to explain paleoseismology and radiocarbon dating while someone a few feet away is belting out "Bohemian Rhapsody" over a loudspeaker but forgetting the words.)

We were pleased to see that everyone spent a lot of time around the (excellent) poster displays from the USGS, which cover everything from earthquake preparedness to stratigraphy of this particular trench to geologic maps of the Hayward fault and the bay area. Most people missed the parking lot displays on the way in (a sign pointing to cracks in the pavement and an offset curb, highlighted with orange spray paint), but we told them what to look for so they could catch them on the way out.

The exhibit will get more press tonight: two or three different TV channels showed up today and interviewed Heidi Stenner, the USGS geologist organizing the exhibit, as well as some of the visitors. So with any luck we'll continue to get good turnouts. The trench will be open through the end of June.

Most of the other docents are either seismologists or seismology graduate students. It wasn't a problem: the questions most people were asking were straightforward questions I could answer easily. But it was fun listening to the other docents and learning from them, and when someone asks a tricky question, you sure can't beat being able to turn to the researcher who did the original study on this trench in 1987 (Jim Lienkaemper) and get the straight scoop! (He also developed the USGS Virtual Tour of the Hayward Fault web site).

The Hayward fault last let go in 1868, a magnitude-6.9 event called "The Great San Francisco Quake" until the 1906 earthquake on the San Andreas took over that title. Trench studies like Lienkaemper's have shown that historically this fault has a large earthquake every 130 to 150 years. Our visitors didn't need a calculator to do the math.

Tags: science, geology
[ 22:46 Apr 29, 2006    More science/geology | permalink to this entry ]

Mr. Sid Meets Linux

Every now and then I search for a map (usually a geologic map) and end up at a USGS page like this one.

The web viewer is impossible, so that link over on the left -- Download Image Now (16M) -- looks awfully tempting, and I always go for it.

What they don't tell you is what sort of image you're getting; after you download that 16M, you end up with a file called something like q250_1388a_us_c.sid, which no image viewer I've ever found considers to be an image file. Even ImageMagick, which can handle almost anything, is baffled by .sid files.

It turns out that .sid stands for "Mr. Sid", a file format for very large raster images. The format is controlled by a company called LizardTech, and it's apparently so scary that no one has ever managed to reverse engineer it. The only way to read a Mr. Sid file is to use one of the programs (available in binary form only) from LizardTech.

Fortunately LizardTech does provide at least one of their programs, mrsisddecode, as a Linux binary. Get it from their download page. Then you can type a command like mrsiddecode -i q250_1388a_us_c.sid -o q250_1388a_us_c.jpg to convert the file into some other image format (which will be quite large -- this particular map is 17170 x 9525).

(Apparently there's an SDK which is also available for Linux, available here. The gdal toolkit used by MapServer and certain other GIS applications make use of this SDK. I hear it's somewhat picky about GCC version, but otherwise works.)

I'm happy that I've found something that will convert MrSid files to a format I can use, but it's a little discouraging that the USGS is restricting its public maps to a format that can be read only with software from a single company. I wonder if the USGS has a contingency plan concerning all these Mr. Sid maps in case anything ever happens to LizardTech? Aren't open formats safer in the long run?

Tags: science, geology
[ 21:50 Apr 18, 2006    More science/geology | permalink to this entry ]

Dream Jobs and Mars Rocks

Driving home from dinner, watching the alpenglow fade from the gleaming domes of Lick Observatory, I found myself thinking about the talk last night: a wonderful geology seminar by Michael Carr of the USGS on the subject of "Water on Mars".

I had a chance to chat briefly with the speaker before the meeting. We got to talking about the moon. It turns out that he spent some of his early career at Lick, working with a few colleagues to make a geologic map of the moon. How? By sketching the terminator every night from the eyepiece of the 36" refractor, and trying to deduce the geology from the topography they sketched. Talk about dream jobs!

It was interesting to compare Carr's talk to the SJAA talk on the same subject earlier this year by Jeff Moore of NASA/Ames (always one of my favorite SJAA speakers). Carr's talk was quite a bit more detailed and heavier on the geologic details, not surprising since he was speaking to a room full of geologists and geology students. He even showed a stratigraphic column of the Burns Cliff area that the Opportunity rover investigated near Meridiani.

I learned quite a bit that I can apply toward my "Mars Rock" collection. I have a set of rocks that are similar to the various interesting rocks on the moon (I finally found some anorthosite a few months ago). I use them when I give presentations on the moon. It goes over very well: I think people get a better idea of what the moon is made of and how its surface looks when they get a chance to handle the rocks and look at them up close.

I have a start on a similar collection for Mars, but of course the most interesting Mars-like rocks to show people aren't the boring black and red basalts; they're the ones the Rovers have been discovering that point to a history of water. So those are the rocks I'm most interested in adding: the sulfates and other evaporites, sandstones made of evaporite sediments, hematite "blueberries" (Moqui Marbles, on Earth), and jarosite.

I'd never heard of jarosite before, but from a bit of web research the day after the talk, it turns out to be one of the minerals implicated in the controversy that was in the news last year about modern-day generation of methane on Mars. Some people attributed the extra methane to the presence of biological organisms, though others were quick to point out that there are plenty of non-biological ways to release methane.

Interestingly, one of the audience members at the talk commented that in the Sierras jarosite is a weak biological indicator (because the biological organisms prevent formation of carbonates, if I understood him correctly). So it's a pretty interesting mineral even for someone who doesn't hold out much hope for finding life on Mars.

Here's a good summary of the rocks found in the Burns Cliffs.

Tags: science, geology
[ 21:27 Apr 12, 2006    More science/geology | permalink to this entry ]

Dark Side of the Moon; M51 Supernova

Yesterday was the annual Fremont Peak Star-b-q. This year the weather managed to be fairly perfect for observing afterward: the fog came in for a while, making for fairly dark skies, and it wasn't too cold though it was a bit breezy. It was even reasonably steady.

I had my homebuilt 8" dob, while Dave brought his homebuilt 12.5". Incredibly, we were all alone in the southwest lot: the most Star-b-q was fairly lightly attended, and most of the handful who stayed to observe afterward set up at Coulter row.

The interesting sight of the evening was the supernova in M51 (the Whirlpool galaxy). It was fairly easy in the 12.5" once we knew where to look (Mike Koop came over to visit after looking at it in the 30"), and once we found it there all three of us could see it in the 8" as well.

We had excellent views of Jupiter in the 8", with detail in the red spot, the thin equatorial band easily visible, and long splits in both the northern and southern equatorial bands. I didn't make any sketches since a family wandered by about then so I let them look instead.

We also had lovely low-power views of Venus and crescent Mercury, and we spent some time traversing detail on the dark side of the slim crescent moon due to the excellent earthshine. All the major maria were visible, and of course Aristarchus, but we could also see Plato, Sinus Iridum, Kepler, Copernicus and its ray system, Tycho (only in the 12" -- the 8" was having glare problems that close to the lit part of the moon) and one long ray from Tycho that extended across Mare Nubium and out to near Copernicus. Pretty good for observing the "dark" side!

Neither of us was able to find Comet Tempel-1 (the Deep Impact comet), even with the 12.5". But after moonset I picked up the Veil and North American in the 8" unfiltered (having left my filters at home), and we got some outstanding views of the nebulae in Sagittarius, particularly the Trifid, which was showing more dust-lane detail without a filter than I've ever seen even filtered.

It was a good night for carnivores, too. We saw one little grey fox cub trotting up the road to the observatory during dinner, and there was another by the side of the road on the way home. Then, farther down the road, I had to stop for three baby raccoons playing in the street. (Very cute!) They eventually got the idea that maybe they should get off the road and watch from the shoulder. The parents were nowhere to be seen: probably much more car-wise than their children (I don't often see raccoon roadkill). I hope the kids got a scolding afterward about finding safer places to play.

Tags: science, astronomy
[ 22:31 Jul 10, 2005    More science/astro | permalink to this entry ]

The Game of Telephone

Remember the game of "Telephone" when you were a kid? Everybody gets in a big circle. One kid whispers a message in the ear of the kid next to them. That kid repeats the message to the next kid, and so on around the circle. By the time the message gets back to the originator, it has usually changed beyond recognition.

Sometimes the Internet is like that.

Background: a year and a half ago, in August 2003, there was an unusually favorable Mars opposition. Mars has a year roughly double ours, so Mars "oppositions" happen about every two years (plus a few months). An opposition is when we and Mars are both on the same side of the sun (so the sun is opposite Mars in our sky, and Mars is at its highest at midnight). We're much closer to Mars at opposition than at other times, and that makes a big difference on a planet as small as Mars, so for people who like to observe Mars with a telescope, oppositions are the best time to do it.

The August 2003 opposition was the closest opposition in thousands of years, because Mars was near its perihelion (the point where it's closest to earth) at the time of the opposition. Much was made of this in the press (the press loves events where they can say "best in 10,000 years") to the point where lots of people who aren't normally interested in astronomy decided they wanted to see Mars and came to star parties to look through telescopes.

That's always nice, and we tried to show them Mars, though Mars is very small, even during an opposition. The 2003 opposition wasn't actually all that favorable for those of us in northern hemisphere. because Mars was near the southernmost part of its orbit. That means it was very low in the sky, which is never good for seeing detail through a telescope. Down near the horizon you're looking through a lot more of Earth's atmosphere, and you're down near all the heat waves coming off houses and streets and even rocks. That disturbs the view quite a bit, like trying to see detail on a penny at the bottom of a swimming pool.

This year's opposition, around Halloween, will not be as close as the 2003 opposition, but it's still fairly close as oppositions go. Plus, this year, Mars will be much farther north. So we're expecting a good opposition -- weather permitting, both on Earth, which is sometimes cloudy in November, and on Mars, where you never know when a freak dust storm might appear.

Which brings me back to the game of Telephone.

A few weeks ago I got the first of them. An email from someone quoting a message someone had forwarded, asking whether it was true. The message began:

The Red Planet is about to be spectacular! This month and next, Earth is catching up with Mars in an encounter that will culminate in the closest approach between the two planets in recorded history.

and it ended:

Share this with your children and grandchildren. NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN

(sic on the caps and the lack of a period at the end).

I sent a reply saying the email was two years out of date, and giving information on this year's Mars opposition and the fact that it may actually be better for observing Mars than 2003 was. But the next day I got a similar inquiry from someone else. So I updated my Mars FAQ to mention the misleading internet message, and the inquiries slowed down.

But today, I got a new variant.

Subject: IS MARS GOING TO BE AS BIG AS THE MOON IN AUGUST?

As big as the moon! That would be a very close opposition!

(Dave, always succinct, said I should reply and say simply, "Bigger." Mars is, of course, always bigger than the moon, even if its apparent size as viewed from earth is small.)

It looks like the story is growing in the telling, in a way it somehow didn't two years ago.

I can't wait to see what the story will have become by August. Mars is going to hit us?

Tags: science, astronomy
[ 10:48 Jun 17, 2005    More science/astro | permalink to this entry ]

Geological Society of America (GSA) Conference

The GSA conference happened back when I was too caught in the whirl of events to write about them. It's been a over month now, but I did want to save a couple of impressions.

The field trips all started way too early. Sure, this is the whining of a non-morning person: but really, when your field trip starts with 45 minutes of everybody standing around because the rental agency that rents the vans isn't open yet, maybe that's a sign that starting a little later might be a good idea. Even aside from the wisdom of scheduling all your travel time for the height of rush hour.

The field trips were worthwhile, though. The most interesting parts were often topics that hadn't sounded interesting at all ahead of time.

The talks at the conference were terrific, total information overload, with maybe six sessions going at once. There are lots of people doing interesting research in geology, often fairly junior people (grad students or postdocs), and many of them are even able to talk enthusiastically about their research using words that make sense to a mere student of the subject. Dry jargon-laden talks did exist, but they were the exception, not the rule.

Everybody was friendly, too, and very willing to talk to students and explain their research or chat about other topics in geology. I went to one of the "Roy J. Shlemon student mentoring lunches" featuring a round-robin of geologists moving from one student table to another to share insight and stories: very helpful and interesting!

The conference organizers obviously worship at the altar of Bill Gates. There was apparently a conference-wide dictum that Thou Shalt Use Powerpoint and Thou Shalt Display On Our Windows Boxen, Not Your Own Machine.

The unsurprising result was that roughly 80% of the talks had at least some problems displaying slides, resulting in cursing, then apologies, with the speaker assuring the audience that it would make much more sense if only we could see the slide the way it had been written. Perhaps half of these followed up with a mutter about having to use Windows rather than a Mac. Macs are clearly big with geologists (though alas there was no sign of Linux use).

That said, the conference ran aggressively on time, each session having an appointed watchdog to sit in front and remind the speaker when time was running out. I've never seen a conference stick to a schedule so well, especially when filled with short (20-minute) talks. I had been prepared for the worst after problems getting schedule information before the conference, but the organization on site (except field trips) was flawless.

All in all, quite a good time. I'm only sorry next year's conference isn't back in San Jose. (It's in Alaska; I'd love to go, but finances will probably prevent it.)

Tags: science, geology
[ 23:04 May 31, 2005    More science/geology | permalink to this entry ]

Geology of Red Rock Canyon

I just finished writing up the final project for my field geology class.

The project involved discovering and mapping the geology of Red Rock Canyon. I'll probably upload the paper and other documents later; for now, just a few notes about the field trip, weekend before last.

Red Rock Canyon is in the Mojave desert, near Ridgecrest. I'd been through a few times before, since it's more or less on the way to Death Valley, but of course didn't know any of the geologic details, other than "Ooh, look at the pretty red and white layers and the eroded hoodoos!"

Actually, it's not technically in the Mojave. One of the reasons Red Rock Canyon is interesting is that it sits at the junction of three of California's geomorphic provinces, at the junction of the Garlock fault (dividing the Mojave from the Basin and Range) and the Sierra Front fault (dividing the Sierra from the other two). The Mojave is bounded on its south end by the transverse section of the San Andreas, but Red Rock Canyon is north of the Garlock fault, in the Basin and Range.

Our four day camping trip (two days of hiking, measuring, and mapping, two days devoted mostly to travel) covered a few square miles around the visitor's center, but we ended up with a surprisingly complete map and stratigraphy. Several people had trouble with the temperatures, which were somewhere in the nineties, combined with the pace of the hikes. That's not really all that hot, especially for desert, but it's hot for a group of people coming out of a bay area winter and an unusually rainy spring, especially the students unused to hiking. (This was all rather ironic since we'd switched our mapping project to Red Rock after being concerned about too much snow at the first choice location, June Lake. Those concerns were probably justified; it was snowing up until a few days before we left, so despite the heat, Red Rock was the right choice.)

Nevertheless, Red Rock is a great location to learn geologic mapping. The structure is fairly simple and easy to see (especially from the top of Whistler's Peak), with a series of cuestas of sedimentary layers each capped with basalt, and a couple of other interesting and distinctive layers in between. Luckily for us, there isn't much complex folding, just a fairly continuous tilt caused by uplift due to the El Paso fault (a branch of the Garlock). The rocks themselves are interesting, with lots of olivine and other crystals in one of the basalt layers, and an area at the base of the other basalt layer containing lovely rocks such as opals -- the area used to be an opal mine.

It's also a fairly nice place to camp, with campsites nestled back among towering cliffs (of the Tr5 fluvial member of the Ricardo formation, if you're curious for details) which provides a bit more privacy and separation from other campers than a lot of parks allow. I'm not really much of a camper (I'm a poor sleeper, and I do like my morning shower) but out campsite converted even the timid non-campers in the class.

White-throated swifts play in the turbulence along the face of the cliffs, calling loudly to each other. Their calls woke me up at daybreak each morning, but setting aside sleep deprivation, it wasn't all bad. It's mating season for the swifts, and it turns out they mate in midair. Two birds come together, and locked together they spiral hundreds of feet downward, finally separating just short of the ground. We have white throated swifts here in the bay area, but I'd never seen anything like their aerial mating dance before; let alone seen it set against towering desert cliffs in the stillness of dawn light.

Other interesting natural phenomena observed on the trip: a barn owl flew over the campsite every night, visible against the campfire light. Zebra-tailed lizards were ghostly white except for their black-ringed tails and some ghostly markings on their backs. We saw lots of jackrabbits and several alligator lizards (the latter have been numerous in the bay area as well, this spring). And we saw a lovely horizontal "rainbow" at mid-day of the first day which turned out, after much research, to be a "circumhorizontal arc". I took a telescope along, but we didn't have very good skies (haze, thin clouds, and disturbed seeing, and with all the campfires it was smoky and not even very dark) so we mostly looked at Jupiter, Saturn, and the moon (we did get good seeing at dusk one night for the moon, and we got a good look at the Mare Nectaris shock rings and the beginnings of Rima Ariadaeus).

A few of our group were disturbed to learn on the way down that they wouldn't have cellphone reception at Red Rock. Horrors! They rushed to tie up loose ends, and managed it before we finally lost reception passing by Mojave.

All in all, a very successful trip, although most of us were awfully glad to get home and jump in the shower. I'm even gladder to have my final report finished. Nevertheless, geologic mapping is fun: I'm happy that I had the chance to complete a map of an area like this. I may even be back to Red Rock some day, to try to trace out the extent of that mystery fault at the north end of the pink tuff breccia layer ...

5/25/2005: photos and report are up.

Tags: science, geology
[ 19:11 May 23, 2005    More science/geology | permalink to this entry ]

Open Source Scientific Image Processing

Anthony Liekens has a wonderful page on open-source Cassini-Huygens image analysis.

A group of people from a space IRC channel took the raw images from the descent of the Huygens probe onto Titan's surface, and applied image processing: they stitched panoramas, created animations, created stereograms, added sharpening and color. The results are very impressive!

I hope NASA takes notice of this. There's a lot of interest, energy and talent in the community, which could be very helpful in analysis of astronomical data. Astronomy has a long history of amateur involvement in scientific research, perhaps more so than any other science; extending that to space-based research seems only a small step.

Tags: science, astronomy
[ 18:30 Jan 17, 2005    More science/astro | permalink to this entry ]

FPOA Star-b-q

Hiking up to the top of Fremont Peak before the FPOA Star-b-q started, we saw the Ghost and the Darkness, squirrel style. A couple of ground squirrels hidden in the tall grass startled as we walked by, and whisked off through the grass, occasionally twitching a tail-tip up above the tops of the grasses but otherwise mostly invisible.

Down in the parking lots, there were some interesting ant or wasp-like insects: furry scarlet head, black thorax, furry scarlet abdomen. The wings were black, too, and they could fly at least a little. No idea what they were.

Learned a new word reading scoops on the way down: Anecdotage, that advanced age where all one does is relate stories about "the good, old days."

Turned out Jeff Moore was the speaker at FPOA. He always gives good talks, but this one was especially good: interpretation of the Mars Rover geologic results so far. Some of his slides showed terrestrial scenes (mostly Death Valley) for comparison with the Martian geologic features, and he mentioned that the terrestrial slides were easy to tell because they were the ones with the pocketknife showing (for scale). So the following morning, I got inspired to whip up a few counterexamples.

Tags: science, astronomy
[ 09:00 Jul 18, 2004    More science/astro | permalink to this entry ]