Shallow Thoughts : : science
Akkana's Musings on Open Source, Science, and Nature.
Sat, 06 Feb 2010
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
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19:25 Feb 06, 2010
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Wed, 01 Apr 2009
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
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19:09 Apr 01, 2009
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Tue, 24 Mar 2009
For
Ada Lovelace Day
I'm honoring Vera Rubin.
In 1948, when she applied to Princeton as an aspiring astronomy grad
student, they wouldn't let her in because women weren't allowed.
(They finally started admitting women in 1975.)
Fortunately, Cornell was more accommodating.
For her thesis, she worked on a project that seemed useful and
uncontroversial. She took other people's data on the redshifts of
galaxies, and catalogued them to see how fast they were all moving
away from us.
Except something unexpected happened. She found that galaxies in one
direction weren't moving away as fast as galaxies in the other directions.
The universe was supposed to be expanding evenly in all directions --
but that's not what her data showed.
In 1950 she presented her results to a conference of the
American Astronomical Society. The results were not promising.
Famous astronomers she'd read about but never met stood up in the
audience to ridicule her paper and say it couldn't be true.
No one would publish her master's thesis.
It wasn't a good start to her career.
She decided to try to find something less controversial to study.
Her husband finished at Cornell and moved to Washington, D.C.. Rubin
and her new baby moved with him, and she enrolled as a PhD student at
Georgetown. They had two children by now; her parents watched the kids
while she took night classes.
She hooked up with George Gamow at Georgetown.
He called her to ask her about her research -- but
said they'd have to talk in the lobby, not in his office, because
women weren't allowed in the office area of the building.
After Rubin finished her PhD with Gamow in 1954,
Her experience trying to present her 1950 paper made her leery of
confrontation. She's said, "I wanted a problem that no one would
bother me about." Working with Kent Ford at the Carnegie Institute in
Washington, she helped design a super-sensitive digital spectrograph,
and they set out to make a huge catalog of data on boring "normal"
galaxies no one else was looking at.
They started with the Andromeda galaxy, M31, the closest large galaxy to
us (and the easiest one to see with the naked eye, if you go somewhere
away from city lights).
And right away they found something weird.
Normally, you'd expect the outer parts of the galaxy to be rotating
a lot slower than the inner parts. Think of our solar system:
Mercury goes around the sun really fast (a Mercury year is only 88
days), Earth goes not quite as fast, and when you get all the way out
to Pluto, it takes 247 years to go around the sun once.
It's not just that it has farther to go to make a circuit around the
sun; it's that the sun's influence is so weak way out there that
Pluto goes a lot slower in its orbit than we do.
Galaxies should be the same way: stars in the center should just whiz
around in no time, while stars at the outer edge take forever.
But Rubin and Ford found that Andromeda wasn't like that. When they
started looking at the stars farther out, they were all going about
the same speed. If anything, the stars at the edge were going a little
faster than the stars in the center.
That made no sense. It didn't follow any normal model of
gravity or galaxy formation. They published their results in 1970,
but no one took them seriously. They decided that maybe something was
wrong, or their equipment was faulty. They decided to try studying a
simpler problem: just measure the redshift of some faint galaxies
and make a catalog of those.
That went well for a while -- except that pretty soon, they ran into
the same thing Rubin had discovered as a graduate student back at
Cornell. Galaxies in the direction of Pegasus were moving away from us
at a different speed from galaxies in other parts of the sky.
She and Ford tried again to present that, but the reaction wasn't
any more positive this time.
Discouraged, they went back to trying to measure galaxy rotation,
hoping Andromeda had just been a fluke.
But every galaxy they studied looked the same as Andromeda,
with the stars far out near the edge of the galaxy rotating as
fast, or faster, than the stars near the hub.
There were only two possible explanations. Either the law of gravity
doesn't work the way we think it does ... or there's a lot more matter
inside a galaxy than what we see with a telescope.
When they tried to present this result, no one believed it, so they
kept measuring more galaxies, always with the same result.
By 1985, they had enough evidence that people finally started paying
attention. As their results got talked about more and taken more
seriously, they came up with a name for the extra mass that makes the
galaxy rotation flat: "dark matter". Yes, the dark matter you hear about
that apparently makes up more than 90% of all matter in the universe.
Not a bad discovery for someone who was just trying to lay low and
catalogue a lot of data that might be useful to other people!
(Rubin's first graduate project, on the rotation of the universe,
has also since been vindicated.)
Vera Rubin is still working at
the Department of Terrestrial Magnetism. Her intellect, hard work
and perseverance are an inspiration, and I salute her on Ada Lovelace Day.
(You can read other people's Ada Lovelace Day posts in the
Ada Lovelace Day Collection.)
Tags: AdaLovelaceDay09, chix, astronomy
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19:12 Mar 24, 2009
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Sat, 29 Nov 2008
Kurt Fisher wrote to draw my attention to the latest
Lunar Photo Of the Day (LPOD), a lovely shot he made of one of my
favorite places anywhere,
Upheaval Dome
in Utah's Canyonlands National Park.
Upheaval Dome has long been strongly suspected to be a massive,
eroded impact crater, but the LPOD highlights a study that finally
puts this (non-)controversy to rest,
Elmar Buchner and Thomas Kenkmann's
Upheaval
Dome, Utah, USA: Impact origin confirmed,
documenting shocked quartz grains in the Kayenta sandstone of
Upheaval's outer ring.
It's about time -- it's been pretty clear for many years that
this structure was an impact formation, not a collapsed salt dome
(the relative lack of salt in the core might have been a clue)
but the park service doesn't seem to have gotten the message,
giving equal weight to the salt-dome theory in all its Canyonlands
literature and signs. Perhaps the Buchner and Kenkmann paper will
finally convince them.
Reading about this gave me the push I needed to update my own
Upheaval Dome page,
adding links to the latest research and to the excellent
Upheaval
Dome Bibliography Kurt has put together.
My page also badly needed a bigger view of the crater itself, so
I stitched together a quick
panorama
of the view from the rim
that I'd shot on a trip several years ago but never assembled.
Tags: geology, astronomy, trails, impact crater
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12:15 Nov 29, 2008
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Sun, 28 Oct 2007
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
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21:51 Oct 28, 2007
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Thu, 07 Jun 2007
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 2X, 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
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17:37 Jun 07, 2007
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Thu, 08 Feb 2007
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
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21:15 Feb 08, 2007
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Thu, 21 Dec 2006
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:
That's easy: it's just NJ,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).
NJ,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:
NJ,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:
N6,12 = N7,12 = 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
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11:59 Dec 21, 2006
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