About this Blog

This blog is a portfolio of my many and varied interests, from cosmology and astrophysics to measurement science and adventures and photography.

Life should not about surviving, it should be about thriving. Life 201 encompass some of my thoughts on how to thrive in our ever increasingly complex technical world.

I hope you enjoy these observations as much as I enjoyed experiencing and exploring them.

My other website, www.beTheSignal.com, covers my signal integrity and professional journalism activities.

Keithley 196 System DMM

I’ve had this Keithley 196 6 1/2 digit multimeter for about 25 years and it works as great today as it did when I first got it.

I usually use it on the voltage scale or the Ohms scale. On the 30 v scale, the least digit is 10 uV. When pushed to the limit, on the 300 mV scale, we can read as low as 100 nV as the last digit.

To measure resistance, the 196 DMM uses 1.6 mA as the source current and measures the voltage across the device, using a Kelvin 4 point method. With potentially as low as 100 nV as the least digit, we can measure below 1 mOhm of resistance.

My 196 has not been calibrated for years, so its absolute accuracy may not be full rated. The specs state an absolute accuracy of about +/- 3 mV on the 3 v scale. This is about 0.1% absolute accuracy.

Reference voltage sources

A simple example is to use the precision DMM to measure the DC voltage of various sources. For example, here are the specific chips, the specs and what I measured.

Device	spec	K196 DMM
AD584	10.000 v +/- 0.030 v	10.00051
	5.000 v +/- 0.015 v	5.00038 v
	2.500 v +/- 0.0075 v	2.49965 v
7805	5 v +/- 0.2 v	5.03011 v
7812	12 v +/- 0.5 v	12.11763 v
7912	-12 v +/- 0.5 v	-12.12306 v

The AD584 voltage reference is a great absolute reference. It appears to be much better than its specs would suggest. It can be an absolute voltage reference to maybe as good as 1 mV absolute value.

9 v Battery Specs

As a final interesting experiment, we happened to have 8, fresh 9 v batteries just purchased. We measured each one to 100 uV.

Here are the values:
9.6665 v
9.6525 v
9.6775 v
9.6708 v
9.6749 v
9.6586 v
9.6668 v
9.6722 v

 

The average is 9.6645 v with a standard deviation of +/- 0.0084 v, with is 0.087% as 1 sigma. Of course, this voltage is temperature sensitive and will change as the battery is used. However, it is interesting that the precision of at least these 8, nominally the same batteries, are within less than 10 mv of each other. A good absolute value for a fresh 9 v battery is 9.665 v.

Resistance of Copper Wire

If you use just two leads to measure a really low resistance, you usually only measure the contact resistance. This is typically on the order of 0.05 to 2 Ohms, depending on the metalization, oxide layers and the scrub you used when making contact. When using banana clip leads to a 1-inch length of 20 AWG gauge 31 mil copper wire, we measured 50 mOhms as the resistance of a section of wire, 1 inch long. This is almost all artifact of contact resistance.

If you look up the resistance of 20 AWG copper wire, it is 10.15 mOhm/foot or 0.85 mOhm/inch. This is very close to what we would expect from a simple calculation.

The series resistance of a 1 inch long length of 31 mil diameter , 20 AWG copper wire should be about

with
rho = 1.7 x 10^-6 Ohm-cm
L = 2.54 cm
D = 0.079 cm (31 mils)

This results in a resistance of 0.89 mOhms for a 1 inch length of wire. This is pretty close to 0.85 mOhms, the AWG table spec, and well below the value we measure with just two wires.

The K196 offers four important features to measure this low a resistance. First, is the use of Kelvin 4-point measurements. Two leads force the 1.6 mA and two other leads measures the low voltage generated.

Second, once the leads are placed very close together, the resulting voltage can be zeroed to remove any offsets.

Third, since the voltages being measured are really small, more averaging helps. The filter setting will average 10 consecutive measurements are report the result.

Finally, using the program setting under the Ohms button, two different measurements are done in each cycle. The current force is turned off and the residual voltage measured. This is automatically subtracted off voltage measurements when the current force is turned on. This technique removes any thermal EMFs.

Using these four methods, the resistance of a 1 inch length and 2 inch length of 31 mil diameter wire were measured.

A 1-inch length of wire was measured as 0.9 mOhms. A 2-inch length of wire was measured as 1.9 mOhms.

I’d say these values are pretty close to what is expected for this wire. This is pretty close to the limit of resistance that can be measured with the K196.

LeCroy WaveAce 2034 Digital Scope General Features

The Teledyne LeCroy WaveAce 2034 is a “gateway drug” into digital scopes. It has the front panel interface typical of traditional analog scopes, but with lots more buttons and features which enable us to tap into its powerful digital signal analysis features.

As with a traditional scope, the WaveAce has the features you expect from a general purpose scope: input impedance of 1 Meg or 50 Ohms, 300 MHz input bandwidth or ~ 1.2 nsec instrument intrinsic rise time, 4 channels and typical triggering options.

Then there are the digitizer specs:

• 2 Gsamples/sec, real time sampling with 50 Gsamples/sec in equivalent time sampling (ETS)
• 8 bit vertical resolution
• 12k samples full buffer (the 1000 series has 1 Meg of buffer depth)

As with all digital scopes, it’s a good habit to always adjust the vertical scale to get the signal as large a fraction of the full screen as possible. This maximizes the dynamic range of the ADC and gives the best signal voltage resolution.

One minor difference from what is usually found in other scopes, the front screen has 8 divisions vertically and 18 divisions in the time base. Both the vertical scale per div and the horizontal scale per div are displayed on the front screen, along with a lot of other useful information.

Sampling rate and time base

There are 12k samples in the memory buffer. The time base selected automatically adjusts the sampling rate. The user does not have control of this feature. Given the time per division and 18 div full scale, this defines how much time is actually displayed on the screen. The sampling rate of the ADC is automatically adjusted so that 12k data points takes about 1.2 – 1.5x longer than the displayed data. This maximizes the time resolution per point.

For example, when the time base is 50 usec/div, there are about 18  div x 50 usec = 0.9 msec of data displayed. The sample rate is automatically set to 10 Msamples/sec, so that 12 k points will record a total time interval of 12 k/10 M = 1.2 msec, longer than the displayed time.

The small wavy line at the top of the screen shows how much of the recorded data buffer is actually displayed on the screen.

The wonders of digital scopes

Then there are the cool new features unlocked with digital acquisition. The scope is basically a very fast digitizer, with a built in display and lots of ways of manipulating the measured voltages as a function time time and analyzing the measured data.

Here are just a few of the really cool, new things you can do with a digital scope. Many other features are written up as separate articles elsewhere on my site.

Pre-trigger display of the data.

The data is always being continuously recorded and shoved into a buffer. The trigger condition decides when the buffer gets displayed or stored. This means you can see what was going on before the trigger condition was met.

In this example, a small crystal microphone was the input to channel 2. It was bounced very lightly on the table top. The scope was triggered on a 20 mV threshold. You can clearly see transient response, which was triggered in the middle of the screen.

Exporting CSV data files

The digitized data and the voltage vs time for any or all channels can be exported into a CSV file. Once it’s in a CSV format, it can be  read by any suitable program, like excel and then plotted or further processed.

For example, the calibration signal was recorded, exported and plotted in Excel. The resulting plot is shown above.

Parameter calculations

There are more than 20 different calculations that can be performed in real time on the measured data to extract a useful figure of merit, either as a voltage or time figure of merit. this could be the average voltage, the rms value, or even peak to peak.

As a freebie, the scope will almost always display the frequency of any repetitive signal on the screen and can record the 10-90% rise time of a signal. In the example above, my DS334 function generator was set for a 10 kHz square wave and recorded by the scope. The frequency was measured as 9.998 kHz. The  rise time is measured and displayed as 16 nsec. This is consistent with the 10 nsec/div time base.

There are a number of other cool digital functions available, such as FFT analysis, but these will be reviewed in other columns.

Life Long Learning at Your Fingertips

I’ve never given up my thirst for learning more about what interests me in the world. I went to school in Cambridge, MA, where there are 30 large universities in the area, each with weekly talks and seminars. I used to hop from seminar  to seminar, eating the free cookies and cakes and listening to the distinguished visitors from around the world.

With the web and my iPod, I can access the same quality speakers who are expert on almost any subject imaginable, but with the convenience of my schedule. I’ve found three important sources for incredibly great learning.

Single-handed Camper Hitch Hook-up

When you are all alone in the middle of the wilderness, how do you hook-up a camper to your car’s hitching ball?

If the camper is not secured, you will be stranded in the middle of nowhere. I found a simple method, using a web cam dangling from the back of the car and viewing its image of the hitching post on my laptop resting on the front seat.

I used to camp in my tent when I visited the dark sky site of the Astronomical Society of Kansas City, in Butler , MO. While this was cheap, it was always a bit of a hassle, both in the set up and the tear down.

Fix for some Windows 7 compatibility problems

I hated Vista and actually downgraded two computers from Vista to XP. Windows 7 is a huge improvement, and I am in the process of migrating all my computers to this new operating system.

As I reinstall old programs, especially those I use for astronomy and astrophotography, I find that some of them do not install correctly under Windows 7. I learned a simple fix that sometimes works. It was from discussion with the folks at Starry Night Education, who create a really wonderful planetarium software tool that I use to control my telescope.

Here’s the trick that sometimes works. If a software tool does not install correctly in Windows 7, then:

Trick to move off-screen windows back on screen

I have multiple monitors on my various computers. If I open and save applications with one monitor configuration, and then change the monitor configuration, or move that application to a computer with a different monitor configuration, I have a problem when I try to open that application again.

The window in which it opens is off the screen and I am unable to see it to even move it back on screen.

I have found a simple trick that works very effectively to find the hidden window and move it back on screen.

If I have an application that opens a window off screen, here is what I do it bring it on screen:

1. press alt-tab repeatedly until the hidden window is highlighted in the alt window
2. press the windows icon button, the shift key and the right arrow to move the highlighted window into the visible monitor

This little trick has saved me endless hours of frustration and works whenever a window is fully or partially off screen and needs to be repositioned.

Rephrase the Political Debate: Goals, Strategies, then Tactics

I am tired of listening to political debate in the media today. Both the politicians and the media interviewing and reporting on them have it all wrong. The fundamental problem is that the discussions are all focused on the wrong issues.

Anyone who has ever taken a project management class or who has the slightest experience in running a successful project to completion knows that project success is based on the articulation of the goals, strategies and tactics and their implementation.

You start with the goals, then develop the strategies to get there, then the tactics to implement the strategies. The entire team must buy into the same set of goals, strategies and tactics. You have to start at the top and get agreement on the goals, then agreement on the strategies, then agreement on the tactics. That is the only successful way of completing a project.

The Vertical Wine Tasting at Stone Hill Winery

In a horizontal wine tasting, you sample different types of wines from different grapes, possibly from different wineries and from different years. You are sampling a shotgun variety of sometimes wildly varying textures, aromas and flavors in the hopes of uncovering a gem among rocks.

In a vertical tasting, you sample the same wine from the same grape and the same winery, but over different years. The only difference in the wine you taste is the year. This is a unique opportunity to experience how a specific wine ages and how the specific growing and harvesting conditions of each year affect the quality of the wine.

How to Nap by Maxwell and Schrodinger

	Schrodinger points out that when you nap style doesn’t count. Comfort is everything. His white moustache is showing.
	Schrodinger illustrates sleeping position #8, nose to nose with a friend. In this case, our friend Rachel.
	Schrödinger shows that if you can’t find a friend to sleep with, a brother will do. This is documented proof that there was a time when both of these now 15 pound cats could fit in this tiny cat bed.
	Here, Susan illustrates that if you fall asleep for more than more than 35 seconds you are liable to wake up with a cat in your lap.
	Of course, Schrodinger discovers the best of all worlds- getting to sleep with Mom and his brother, Maxwell.

Screen Capture for an iPhone

There is a simple way of taking a snap shot picture of whatever is currently displayed on the iPhone screen. It is described in the iPhone help files under the camera.

To record the screen, press the top off-on button at the same time as the home button, the round depression at the bottom center of the iPhone.

A copy of whatever is on the screen at the time is then sent to the camera roll collection of photos which can be viewed with the photo tool or downloaded from the iPhone like any photo.

This means that if I am viewing a map, or directions, or a note, or even a recorded lecture and want to take a snapshot, it’s a simple matter of clicking the two buttons simultaneously and I have an instant record.

Stories in Pictures for April 2010

	The storm season began with thunderstorms building over the plains of Kansas.
	April is here with flowers in bloom in downtown Kansas City
	I bet you’re thinking, “How is it possible for this kid to have such great aim?” In this one of the many fountains in the “City of Fountains”, Kansas City, the water is actually coming out of the frog and shooting upward.
	In addition to the two port impedance analyzer and 4 port network analyzer, I also have a 1 port cat scanner. Rosalind watches over all measurements in the lab.
	Example of a sun dog to the south of the setting sun. This is created by scattering of the sun light from ice crystals at high altitude
	While clouds offered a very nice contrast for the setting sun, they really screw up astronomical observation plans
	Indeed, the view over my telescope was not very encouraging with the clouds coming in
	Finally finished setting up camp with the Aliner, canopy and telescope. With the clear sky, it was perfect weather for some solar observing. The dog found a comfortable spot in the shade.
	With the clear sky, it was perfect weather for some solar observing. The dog found a comfortable spot in the shade.
	A key benefit in living in our neighborhood in Kansas is the proximity to a large number of beautiful walking trails. This is a view of a creek, just before the beginning of Spring, before the leaves came out.
	On my recent trip to San Jose, I noticed this great cloud formation as the sun set. Almost felt like Kansas.
	Maxwell found a lizard walking across the sun room floor. He isn’t the swiftest cat in the house, and wasn’t quite sure what to do with it.

Maxwell and Schrodinger at 2 Years Old in 2003

	Since we kept our two cats as inside only cats, I felt sorry for them not having a chance to learn to hunt. So, I bought a live mouse for them to practice with. I don’t think they had a clue what to do with it.
	Goldfish, on the other hand, were more interesting. I would buy a dozen to feed Sir Isaac, the garter snake, and those he did not eat, the cats could play with.
	Susan was able to teach Maxwell to change channels using the remote control, but he would only change it to a channel he wanted to watch.
	“Mom, look what Schrodinger did to me! I was sleeping in the clean clothes basket like I always do and he tipped it over. Make him stop!”
	This was the last time I gave Schrodinger one of my papers to review for comment. He really did not like the first draft at all.

Three Microsoft Windows Products I Actually Like

The first computer I bought with my own money was a Mac. It was love at first sight. I became a “pod” person. Back in 1985, it was like all of us Mac fans shared this secret. We knew how “insanely great” the Mac was, but those not part of our secret society didn’t have a clue.

When I met a stranger in my travels who had a Mac with them, we would exchange a smile and know exactly what it meant.

“We Broke It, Now We Own It!”

In the summer of 2009, we caught five raccoons over a period of about a month using a live trap. I would shove the trap and raccoon in the back on my car, drive it two miles and across a freeway to a lake with acres of wilderness and release it. These were five fewer creatures to eat Susan’s garden on our upper deck.

After setting the trap with a piece of chicken one night, I came down to the patio the next morning to find that instead of catching a raccoon, we caught a kitten. This cat could fit in the palms of two hands held together.

iPhone Favorite Apps: AT&T Navigator

Whenever I’ve rented a car in the past 8 years, I’ve always gotten a gps navigator. I’ve become dependent on it as an essential tool to get around in a new city.

Four years ago, when Verizon came out with VZ Navigator, I thought this was great. It was exactly the same turn by turn voice navigation as the dedicated navigators, like from Garmin, but you carried it around with you.

When I switched to the iPhone, I tried out a number of the navigator features and found the AT&T Navigator to be the best. It uses real time information feeds, so does require 3G network access. However, it also gives traffic update reports and, of course, allows local search for facilities nearby.

I use it locally to find the nearest Starbuck, and to check out new restaurants when I am looking for inspiration.

The turn by turn voice directions are as good or better than other navigators and I like the posting of the ETA to my destination. This is a “First Screen” app for me.

University Astronomy 101 in Your Pocket

Now that you have discovered how much you love astronomy, do you regret not paying attention in your college classes, or kick yourself for not even taking an Astronomy class when you had the chance?

It’s not too late. In fact, you can listen and view Astronomy 101 classes from some of the top universities or listen to invited lectures by the scientists who are making the great discoveries we read about each day. Best of all, it’s completely free, and you can take it with you on your iPod or iPhone. A new world of learning is available to you at iTunesU.

All you need is a computer and internet access. Download Apple’s completely free iTunes program for the Mac or the PC. Go to the iTunes store and click on iTunesU listed on the left hand menu.

Hacking a Cat Box to Last Two Weeks Between Emptying

We have three cats. Two of them, 9 year old males, are at least 15 pounds and the third, a 2 year old female, that weights only 8 pounds, eats (and poops) like she is 15 pounds.

That’s a lot of cat litter each day that needs disposal. Ideally, I want an automatic cat box that I don’t have to clean out for weeks at a time, doesn’t make a mess, never needs maintenance and the cats can use effortlessly. I accept the fact that I will have to add kitty litter every so often.

A Perspective from Picasso

Picasso was on a long train ride, on one of those trains that has seats facing each other. Across from him sat a man who recognized him, but said nothing for a good 30 minutes, and then began mumbling to himself, “don’t like it. ….can’t understand it….shouldn’t be allowed…”

After a few of these comments, Picasso interrupted him and asked him, “What are you talking about?”

The man said, “Modern art. It’s too abstract. I don’t understand it, Galleries shouldn’t show it.”

“What should they show?” Picasso asked.

“Realism. They should show reality, the way the world really is.”

“Give me an example,” Picasso asked, and the man pulled out his wallet and showed a picture of his wife. “This is a picture of my wife. This is realism. This is how the real world is.”

Picasso looked at it, turning it over and said, “My, she’s awfully small, …and awfully flat.”

Life Is Too Short To Drink Cheap Wine

For 35 years, I’ve occasionally drunk wine. For most of this time, I didn’t have much of a discriminating pallet, even with a few casual wine tasting classes and visits to wineries.

And then I had a chance to sample a glass of Silver Oak Cabernet. This was a $70 bottle of wine. After this glass, I realized there was a qualitative difference in a $70 bottle of wine from the usual $7.99 wine I used to drink. Sometimes paying extra for a great bottle of wine is worth it.

Since then, I’ve tried to pay attention to wine and taken the opportunity to keep track of the ones I like. It’s all about price range and quality.

For under $10, my favorites are:

• Chardonnay: Chateau St. Michelle
• Pinot Noir: Gallo Reserve
• Shiraz: Yellow Tail

For ~$25:

• Cabernet: Simi
• Pinot Noir: Castle Rock Russian River Reserve
• Chardonel: Reserve, Stonehill

And then when I really want to splurge, for $50-$70 its

Cabernet: Silver Oak

Merlot: Grgrich

As a special note, Grgrich is the winery that put California Chardonay’s on the map. The 1973 Chateau Montelena Chardonnay, crafted by Mike Grgich, took first place at the famed “Paris Tasting” in 1976, beating France’s best white Burgundies.

The entertaining fictional movie Bottle Shock, was based on this earth shaking event.

With these price points and favorites in mind, I like to compare new wines, always looking for ones that beat my current favorites. That’s often the fun part of visiting wineries to taste their offerings- the possibility of discovering a new favorite.

If you have a recommendation, let me know!

Top Shelf Astronomy 201 Courses

Looking for an astronomy class a little beyond the basics, but not requiring a PhD and taught by the experts? Here are four recommendations that are “out of this world.”

 

The Best BBQ Chicken in the World

The best BBQ chicken in the world is “beer in the butt” chicken. I heard about this way of cooking chicken on a grill many years ago, tried it and was hooked. Apparently, I am not the only one. I did a Google search and found more than 16,000,000 entries for beer in the butt chicken on the web.

Could this be the Ideal Breakfast?

A bowl of instant oatmeal with a handful of blueberries could be one of the healthiest breakfasts to eat. It’s a great trade off between low calorie, filling, quick and easy and it’s probably pretty good for you.

 

Fly High, Swim Deep

The signature line of Curt Hillfon, Swedish artist, 1943-

“Whatever you do, do it well,” Curt Hillfon told me. “If you are a bird, fly high. If you are a fish, swim deep.”

A Moment of Tranquility in the Singapore Changi Airport

Experience an oasis of peace and calm communing with the butterflies, in the middle of one of the busiest airports in the world.

The Earliest Influences that Launched Me On My Life Paths

I was invited to talk to a group of six-graders on what influenced me when I was their age, to launch me on the path I followed through life. This gave me an excuse to reflect on what stands out now as important then.

In hindsight, I think there were three things: I had a few simple toys which created an itch to know why, the space program and science fiction books and shows.

TiVo Stream- Making it Even Easier to Watch Live or Recorded TV Anywhere, Anytime.

The TiVo set top DVR (digital video recorder) box started the revolution of time shifting TV watching habits and fast forwarding through commercials. Like “Kleenex” and “Xerox”, the name of the product has been turned into a verb, as in to “TiVo” a show: record it when scheduled for later viewing.

It changed the way I watched TV. The first revolution was moving TV shows to my schedule, rather than the network’s schedule.

I started using TiVo in 2000, when it first came out. There were initially two key features I really liked: a simple and robust user interface and the ability to watch recorded shows anytime convenient for me, not just when they were scheduled.

TiVo Stream- Making it Even Easier to Watch Live or Recorded TV Anywhere, Anytime.

The TiVo set top DVR (digital video recorder) box started the revolution of time shifting TV watching habits and fast forwarding through commercials. Like “Kleenex” and “Xerox”, the name of the product has been turned into a verb, as in to “TiVo” a show: record it when scheduled for later viewing.

It changed the way I watched TV. The first revolution was moving TV shows to my schedule, rather than the network’s schedule.

I started using TiVo in 2000, when it first came out. There were initially two key features I really liked: a simple and robust user interface and the ability to watch recorded shows anytime convenient for me, not just when they were scheduled.

Area of a Circle with Simple Geometrical Model

Thomas Greenslade wrote a very simple article for the Physics Teacher in March 2011 sharing a beautiful, wooded model from the L E Knott Apparatus Company which illustrates, at a glance, the principle that the area of a circle is really 1/2 x radius x circumference.

 

Smart Grid Presentation by Bill Parkhurst

On Thursdays, April 8, 2010, Bill Parkhurst of Cisco Systems, presented a talk on the Smart Grid at the Kansas City section of the IEEE in Overland Park, KS.

Fundamentally, Bill said, the Smart Grid is whatever Steven Chu, the Secretary of Energy, says it is. He has $4.5B available to fund Smart Grid programs. How this money is used will define what the Smart Grid becomes.

The Vertical Wine Tasting at Stone Hill Winery

In a horizontal wine tasting, you sample different types of wines from different grapes, possibly from different wineries and from different years. You are sampling a shotgun variety of sometimes wildly varying textures, aromas and flavors in the hopes of uncovering a gem among rocks.

In a vertical tasting, you sample the same wine from the same grape and the same winery, but over different years. The only difference in the wine you taste is the year. This is a unique opportunity to experience how a specific wine ages and how the specific growing and harvesting conditions of each year affect the quality of the wine.

Gravitational Lensing in a Wine Glass

On May 20, 2009, Prof Patricia Burchat, the Chair of the Department of Physics at Stanford University, presented the last lecture in the 10th season of the Silicon Valley Astronomy Lectures. She gave what I have found to be the best demonstration of gravitational lensing.

Of course, there are many examples of gravitational lensing in Hubble photos of galaxies. These are sometimes called Einstein rings and are the direct result of the bending of light by gravitational fields.

Modern Cosmology was Founded on Luck

The Hubble Constant, which describes the velocity-distance relationship for galaxies, is the foundation of modern cosmology. It establishes the time and distance scale of the universe and the dynamic nature of the galaxies since the beginning of time. It is all the more remarkable that the original data Edwin Hubble took was flawed.

Last Man on the Moon Speaks at Linda Hall Library

Harrison Schmitt, the last man to walk on the moon, spoke to a full house at the Linda Hall Library on Sept 2, 2009, as part of the “To the Moon and to the Planets Beyond” lecture series.

Schmitt left the moon on December 14, 1972 as part of the Apollo 17 mission. He was the only geologist to visit the moon, receiving a PhD in Geology from Harvard. And as the only non military and non professional test pilot among the Apollo crews, much to the consternation of the NASA controllers on earth, he was prone to falling while hunting rocks on his moon walks. In this photo, his suit is covered in moon dust from his close up encounters.

Summer Science Camp for Big Kids

If you missed out on summer camp as a kid, as I did, it’s not too late. But this time, you don’t have to rough it.

For the last few years, I’ve attended various star parties during the summer. These are gatherings of enthusiastic amateur astronomers (not all of whom are Geeks) who get together for a few nights during a new moon with telescopes, campers and tents, to look at the stars and share the sky. They typically span 3-5 days.

Daytime is pretty casual with some events for kids, but mostly time to sit back, read, sleep and chat with folks. Most star parties also schedule a professional astronomer or scientist to speak after dinner. Night time is the time to bring out your scope and observe.

 

Essential Telescope Principles: The Real Meaning of Focal Length

This is part 1.

The properties of telescopes are often presented in a confusing way. In fact, it is simple if you keep in mind what a telescope is really doing.

Colliding Galaxies at Your Fingertips

When we look at a few Hubble photos of distant galaxies we may get the impression the universe is a static place. Other than the occasional supernova brightening, the galaxies we see haven’t changed much over the hundred years of observational history. But, it may well be the dynamics of energetic galactic collisions that created the variety of visually distinct galaxies we see today.

Though not so common today, images of many colliding galaxies, frozen in time, have been captured. In 2008, NASA and the Hubble Space Telescope Science Institute released a collection of 59 colliding galaxy images, shown above.

Book Review: The Alchemy of the Heavens by Ken Croswell

Astrophysicists sometimes use familiar words, but in a very different way than we are used to. Take for example the term metal. To an astrophysicist, a metal is any element with an atomic mass greater than Helium’s.

That’s because only hydrogen and helium were created during the big bang and all higher atomic mass nuclei had to have been created in some stellar process. This story of nucleosynthesis and what it tells us about the structure of the universe, the origins of our galaxy and stellar evolution is detailed in Ken Croswell’s book, The Alchemy of the Heavens, published by Doubleday, 1995.

Life Long Learning at Your Fingertips

I’ve never given up my thirst for learning more about what interests me in the world. I went to school in Cambridge, MA, where there are 30 large universities in the area, each with weekly talks and seminars. I used to hop from seminar  to seminar, eating the free cookies and cakes and listening to the distinguished visitors from around the world.

With the web and my iPod, I can access the same quality speakers who are expert on almost any subject imaginable, but with the convenience of my schedule. I’ve found three important sources for incredibly great learning.

Making Career Path Decisions

Last year, the convergence of two events gave me reason to articulate my recommendations on how to decide on a career path.

Our niece stayed with us for more than a year and we watched her struggle trying to decide what she wanted to do with her life.  Anyone who is over 50 years old has gone through this process at least twice, and sometimes more than that.

For more than 20 years,  I have been an MIT education councilor, interviewing high school students who apply to MIT. This last year, I encountered a few students who didn’t have a clue what that wanted to do in life and asked for some advice.

Here’s what I tell them: