Monday, February 27, 2006

My apologies... and the Ghost Particle

I must offer apologies for not posting per diem as I tried to do after reading a doomsday piece about the power law associated with blog readership, but I have two separate presentations about computer security and the relationship between magmatism and crustal extension this week, a possibly fantastic statistical association. This never normally happens but I manage to inadvertently cause it, so I can't complain.


Nova aired last week "The Ghost Particle", simply the best episode of Nova in the past five years. This was a science story that explained neutrinos and Pauli's proposal for them in the excess energy from beta particle (aka electron) emission, the first detection from a nuclear reactor from Reines and Cowan, and the fantastic Homestake Mine experiment from Ray Davis Jr., and John Bahcall's theoretical calculations that pushed the experiment foreward into the modern three flavored neutrino theory. Davis' son, Andrew, is a scientist here at Chicago who cofounded the Chicago Center for Cosmochemistry.

P.S. The link to the Ghost Particle goes to the producer's page rather than the main page because he lists the rules in making a compelling story, although he believed in possibly keeping it too simple--keeping the idea of a neutron out of the atom's nucleus in the animations for the nuclear reactions was in my opinion unnecessary. But still, bravo to you, a fantastic Nova.

Friday, February 24, 2006

Minor planet Turandot occultation

Steven Lucy and myself from the Ryerson Astronomical Society attempted to watch as the minor planet (530) Turandot passed in front of a star as seen from Chicago, but alas, the tiniest of patches of clouds appeared but two minutes before the occultation and quickly foiled us.

Occultations are great science because you can directly observe the profile of the asteroid precisely--literally a shadow of the asteroid passes across the Earth.

Turandot was discovered by Max Wolf in 1904.

Wednesday, February 22, 2006

VLF radio part 2: sferics

VLF Radio Part 1 was published here.

Here's a simple experiment you can do right now. Get a male to male 1/8" mini stereo cable. Hook one end of it into the microphone input of your computer. Get three alligator clips, a length of coaxial cable, and the longest single wire you can lay outside. Connect the "sleeve" of the cable (diagram here) to the coaxial cable's shield, and connect either the tip or ring (or both if you can manage it) to the coax's center conductor. On the other side of the coax, connect the center conductor to the long wire, and run the long wire out on the ground away from your dwelling.

Make sure your computer's mic input is turned on, and turn up the volume on your computer speakers. You should hear lots of random clicks, of very high frequency. (Ignore the loud hum for the moment). They come and go, sometimes clicks will seem to come in sequential patterns, other times not. They vary in volume too. Occasionally you may hear one that sounds like a tweek rather than a pop. What are they?

Ever listen to a AM radio when a thunderstorm was nearby? The clicks you are hearing (I hope you are trying this right now) are radio waves created from lightning strokes from around the world. The louder clicks are obviously coming from closer by. In the US, you can use's or Vaisala's maps to determine where the closest strikes are. Even when there is no lightning in the continental United States, I still hear faint clicks from many thousands of miles away. The strength of the radio emission from lightning falls off as frequency increases, and the bulk of the energy is emitted under 15kHz. You only get to hear it on AM radio (550kHz to 1710kHz) when it's much closer and stronger at your listening point.

Sferics, as these lightning signals are called, is short for "atmospherics", or generically the ubiquitous noise that occurs at these VLF frequencies. They are refracted by the ionosphere and propgate around the world.

Download and install your favorite audio spectrograph software. I now use Spectrum Lab, but there are others you can use or try. This software will show you a time vs. frequency graph of your signal, and you can see and save lots of interesting details with it.

The World Wide Lightning Location Network can give you a sense of what you can see with a simple look at these radio waves with frequencies in the Very Low Frequency band.

Want to know more about sferics? Take a look at this PhD thesis by Steven Cummer.

Tuesday, February 21, 2006

Where I'm spending my spring break

The Eldorado Mountains of southern Nevada. I'm taking a field course in geology looking at granitic intrusions and specifically the intrusions in the mountains near Nelson and Searchlight. They intruded into existing Precambrian metamorphic and earlier Cretaceous intrusions during the Miocene between 18 and 15 million years ago, just before the whole Basin and Range began extension. The extension of Nevada breaks the crust into chunks that, like a shelf of books, tilts on their side as you allow them to separate, and in this case gives wonderful access to a vertical slice of the crust that normally is buried kilometers deep. Literally speaking, you can walk from the top of an old magma chamber all the way down to the bottom of the chamber (in the case of the Searchlight pluton, it's a 10km walk).

In the above photo, the Colorado River winds in from the left side of the photo and in the far center you can see Lake Mohave. The road to Nelson comes in from the lower right. Spirit Mountain, the largest pluton in southern Nevada covering over 500km2, appears as the distant mountain to the upper right. Laughlin is not far from there. If you look closely at the large image my digital camera has a defective pixel roughly a third of the way from the center towards the right side, and it points to about where we'll be.

On the same trip in August I have a photo of Eldorado Dry Lake Bed being decidedly not dry. The dry lake is framed just below the first shot of the Eldorado Mountains--you can see the road to Nelson in both.

Monday, February 20, 2006

Periodic Table table

This is great: a real periodic table. Everyone of a certain age who watched Cosmos probably dreamed of doing the same exact thing. When I was a kid obsessed with chemistry I emulated Sir Humphry Davy, who isolated a number of elements including all the alkali earth metals for the first time. Davy didn't do bromine, but it was probably my favorite isolation. I ran the output of several 9 volt batteries connected in series through two carbon rods into a solution of potassium bromide. A dense, orange-red-brown liquid appeared at one of the terminals and flowed down to the bottom of the beaker. It stunk of halogen and something poisonous. Truly, it is named appropriately: bromos (βρωμος) meaning "stench" from Greek. I put the beaker on my windowsill and after a few days converted it into hydrobromic acid.

LaSalle Nuclear Unit #1

Steven has a log of the web page of my geiger counter and is saving it in a standard format for me.

LaSalle Nuclear reactor #1 had a problem last night while they were shutting down the reactor for refueling. It had been the longest time in-between refuelings for any reactor at over 700 days. NEI Nuclear notes mentioned it recently. While pushing the rods in completely to stop the power generation for refueling, 3 of the 185 rods had indicators that failed to report where they were properly.

I checked and the winds were coming out of the southwest, and to alleviate any concerns, no additional radiation was detected here in Chicago. Even if you don't believe them when they said no releases occurred, my downwind site didn't pick anything up.

Here's this morning's results.

The last minute results are at Live Regenstein basement radiation readings

The archive is at -- Very big file.

P.S. The Tribune is hyping this on their home page, labeling it as "Nuclear Emergency" without mentioning how it's over and nothing was released. If something does get released, I hope the hysteria is more subdued.

Friday, February 17, 2006

Transmitting audio over light (laser or LED)

Want to send your audio information via a light wave across the room? I built this simple circuit with some modifications that transmits an audio signal via light. The signal simply amplitude modulates the light intensity (aka AM) of a LED and a receiving cadmium sulfide photocell changes its resistance as the intensity varies. Both sides have 8 to 1000 ohm audio transformers, although on my circuit I ended up using the transformer on the receiving side as a voltage booster. I also added a battery and resistor to the photocell receiving side.

Be careful--I used an LED because I destroyed a cheap laser pointer when trying the first circuit. The problem with it is the sound card audio is approximately 1 Volt AC at max, and this gets converted to ~12.5V on the other side (although I found output was usually around .5 V on the sound card and ~4 to 5V on the other side of the transformer). At least that's what I measured--I've seen people read 4V on sound cards, but I don't know which is correct.

I ended up using a white LED since it was my brightest LED, but I also have a superbright red LED that seems to work even better.

This is a 343KB video of the circuit in action. I block the beam and the sound volume dips.

I hate using the future tense on the web, so I'll say I promise to post a circuit diagram soon... --- and here it is! (keep in mind it's a CdS photocell, not a photodiode. I couldn't find the symbol in TinyCAD).

Forrest Mims wrote the book on this sort of thing, and there is a better circuit in Getting Started in Electronics, simply the best starter book for people interested in electronics and how things work.

Friday, February 10, 2006

Sun snow shadows

snow in car shadow
Coming to work on Thursday gave a good example of the power of the sun, as it melted the snow precisely around the car's shadow. The little bit of overlap is the Sun's motion across the sky combined with the time it takes to melt the thin layer of snow.

Click here for another example.

Tuesday, February 07, 2006

Saturn, the Moon, and Ryerson

After the Ryerson Astronomical Society meeting Monday night, Steven, Katie and I went up to the dome and observed on a nice clear night.
The Moon
The Moon aesthetically framed.

The telescope looking at the Moon.

Steven at the controls.

Monday, February 06, 2006

Astrology: oh yeah!

Nice rant on a review of the new astrology book:
Ignorance and Anti-Science in the NYT Book Review from Mark at Cosmic Variance

No, Dick, the real problem is that the willful twisting of hard-won scientific progress by people like you leads to such raging rates of belief in pseudoscience and nonsense.

Go Mark!

Friday, February 03, 2006

IR hosta (plantain lily)

This is a near-infrared image of the leaf of the hosta plant, also known as a plantain lily. It was taken during the same session as this Linne image.

Previous discussion on why leaves are so white in the near infrared is at here.

I've talked about my setup a couple of times before:

Wednesday, February 01, 2006

More science on 2003 UB313

A number of 2003 UB313 related news articles has come out in the past week, and Nature will have a paper published tomorrow regarding a size measurement using IR vs. visual albedo. 3000km+-400 diameter , roughly 10% error. It makes the albedo of 2003 UB 313 to be 60%, like Pluto. While many of the big KBOs are bright, not all of them are, and it remains an area of speculation. What's the albedo of crystalline water ice on Quaoar? Why is the bulk albedo of it only 12%? Small areas of fresh ice? Is there a resurfacing going on for the high albedo KBOs?

Meanwhile, ScienceNOW reports that Brown et al made a direct HST measurement of the disk, calling it just a touch over the diameter of Pluto at 2300km.

The naming of the KBO is stuck in international bureaucratic limbo, deep in committees that can't agree on a definition of what a planet is. It depends on what the definition of 'it' is. (I guess).

The satellite so far has only one observation of it published. As soon as a second image is taken and reduced, an accurate determination of the mass of 2003 UB313 can be made.