A Spectacular Speck on the Sun

Today, Tuesday June 5, 2012, the planet Venus— the planet in our solar system that is closest to the shape and size of Earth —will leisurely pass squarely between the Earth and sun.

The Transit of Venus, as it is called, is a once (or maybe twice) in a lifetime event. If at all possible, make an effort to see it today, because you won’t have another chance… at least until the year 2117.

While it will not be visible everywhere in the world (see map), it will be visible for all of North America, Asia, Australia, and eastern Europe. (The latter, towards sunrise on June 6.)   The transit begins at 22:09 UTC, peaks at 01:29 UTC, and ends at 04:49 UTC.  Here in the PDT time zone, that’s 3 PM, peaking at 6:30 PM, and finishing below the horizon. (More at the LA Times.)

Now, how to actually view it?

If you were clever, you might have stashed away an eclipse-viewing filter from the recent solar eclipse.  If not, another option— one that is cheap and easy to find at hardware stores —is a set of welding glasses with a #14 filter. (That’s black glass. Sadly, those dark green goggles that you found in the shed are likely not safe for direct solar viewing.)

But, as the Ontario Science Center warns you,

Be careful: there are many materials that may seem to block out the Sun’s rays, but which are not safe to use for solar viewing. DO NOT LOOK AT THE SUN THROUGH sunglasses, photographic neutral density filters, polarizing filters, photographic film, dark plastic such as garbage bags, or smoked glass.


The other approach to consider is indirect viewing. You can build a pinhole projector, or a simpler yet version.  You can also use a telescope set of binoculars to focus sunlight onto a surface for indirect viewing. (Using binoculars or a telescope for direct viewing requires a carefully chosen solar filter, to be safe.)

If all else fails— maybe you’re in cloudy Portland —NASA has got you covered. Head right over here for a “live” feed of solar pictures from the SDO spacecraft in orbit around the Earth, and updating every 15 minutes.

Update: A nice summary of the historical background of viewing transits of Venus is here.

[Image source]

Shadows of an Eclipse

Eclipse 2012- 5

There were a lot of amazing things that we saw this weekend at Maker Faire— everything from live demonstrations of snails creating artwork (by Presley Martin) to the DIY pick and place machine (from buildyourcnc.com).

There was also something special in the sky: the solar eclipse on Sunday.

Eclipse 2012- 9

Viewed elsewhere (e.g., further north in California) this was an annular eclipse, where the sun does not disappear entirely, but instead becomes a ring of fire (since the apparent size of the moon is not large enough to block the full disk of the sun).

For us at Maker Faire in San Mateo, it was a spectacular partial eclipse, which we were able to view through solar viewing filters, kindly handed out by the Exploratorium.

Eclipse 2012- 8

Of course, it turns out that you don’t actually need a solar filter to watch the eclipse. Any little aperture— in this case the cap between my hand and the camera —can act as the pinhole in a pinhole camera and project the image of the sun onto a surface.

Eclipse 2012- 4

Eclipse 2012- 2

So if you’re not sure if an eclipse has started, or how much of an eclipse it is, just hold out your hands and make some little apertures; the shadows will show up with little bright spots in the shape of the sun, whether that’s a circle, ring, or crescent.

Eclipse 2012- 1

Stranger yet is to look around at all the shadows that you see every day. Even the shadow of your hand takes on an unexpected shape when the sun is anything other than round.
There are actually five outstreched fingers on my hand here, but you can hardly tell that when every bit of light that seeps through (or around the edges) projects a crescent-shaped image.

We take for granted that the shadow of an object will the same shape as the object, but as you can see, that isn’t necessarily the case when the light source isn’t round.

A stunning display of natural birefringence

Penn Museum - 2

In a recent visit to the Penn Museum– the University of Pennsylvania Museum of Archaeology and Anthropology –we came across a most unusual artifact in their Chinese Rotunda: a giant crystal ball:

Penn Museum - 5

For a higher-quality image– without the display case– take a look here.

Here is what the display placard has to say:

Penn Museum - 3

Crystal Sphere
Rock crystal, Silver Stand
Qing Dynasty (1644-1911 CE)

An ornamental treasure of the Imperial palace in Beijing, the crystal sphere was said to have been a favorite possession of the Empress Dowager Cixi (1836 -1908 CE), under whose watch imperial China crumbled. The rock crystal originated in Burma and was shaped into a sphere though years of constant rotation in a semi-cylindrical container filled with emery, garnet powder, and water. The forty-nine pound flawless crystal sphere is believed to be the second largest in the world. The stand in the shape of a wave was designed by a Japanese artisan.

So, not only is it a giant crystal ball, but it’s a historically interesting giant crystal ball. But besides that– and its brief modern stint as a hat rack –what’s genuinely remarkable about this particular artifact is that it’s made from a chunk of rock crystal, better known as quartz crystal.

Now, those “crystal balls” that run-of-the-mill fortune tellers use are often just glass– glorified playground marbles or perhaps so-called lead crystal, which is actually just another type of glass.

Quartz crystal, on the other hand, has a structured atomic lattice that leads to some very interesting physical properties including piezoelectricity, triboluminescence, and birefringence. These properties arise from the crystal structure itself; they are typically minimal or absent in glasses such as fused silica (glass made by melting quartz crystal).

Penn Museum - 4

While the museum probably wouldn’t want you compressing or grinding their crystal ball for piezoelectricity or triboluminescence experiments, the birefringence is boldly sitting out on display.

Let’s look a little closer:

Penn Museum - 6

The sign, across the room reading “TEXTILES” is not just inverted like it would be with a spherical lens, but also– plain as day –appears as double image, even through our single camera lens.

Why? Quartz crystal is a birefringent material, which means that light rays entering the material experience two different indices of refraction, depending on their polarization and orientation with respect to the crystal lattice. In practice, our eyes see all polarizations, so this means that the crystal ball acts like a superposition of two glass balls with different indices of refraction– and light rays entering the sphere at any given point can follow two different paths to reach your eyes. Hence the double image.

It’s also worth noting that the two separate images are composed of photons with perpendicular polarization. If you were to look at this sphere through a linear polarizer (e.g., one lens of the 3D glasses that they use in modern movie theaters), you could turn it such that only one of the two images was visible at a time.

Birefringence is not particularly rare, and there are materials (like certain forms of calcite) that have huge, easily visible birefringence. Optical devices made from flawless natural calcite, exploiting this property, are tremendously important to scientific research and industry.

We tend to think of a quartz crystal as being perfectly clear– not something that gives you a double image when you look through it. That’s because quartz is only very weakly birefringent, especially when compared to calcite. Quartz is, however, still extensively used in industry in applications for which high transparency and very slight birefringence are key, such as optical wave plates. And, what’s truly remarkable about the Penn Museum sphere is that this tiny property– usually so hard to see –is so plainly visible to the human eye.

Penn Museum - 8

Finally, as we mentioned, the amount of birefringence depends on the orientation of light rays with respect to the crystal itself.

This means that if we walk one quarter circle around the sphere to a point where we’re closer to looking directly along (or perhaps, perpendicular to) the optical axis of the quartz sphere, the image suddenly becomes (if you’ll pardon the pun) crystal clear.

Field trip: Marine Mammal Center

Marine Mammal Center

The Marine Mammal Center, located in Sausalito, California, is an institution dedicated to the study and health of marine mammals, particularly seals, sea lions, otters, and whales. In their extensive veterinary programs, they rescue, rehabilitate and often release many of these animals, and work to identify causes of illness and injury.

Visitors to the center can see some of the healthier patients (not the ones in the ICU) in these outdoor hospital pens shaded by solar panels as well as the research labs and a great many exhibits about these creatures.

Marine Mammal Center

We were recently invited to a behind-the-scenes tour of the center to get a first hand look at some of the amazing equipment and machinery that is needed to run a hospital for these unique patients.

In what follows, we’ll show you some of the neat things that most visitors don’t get to see, from glowing purple plasma to Nike missile silo blast doors.

Continue reading

Gaunt and Glimmering Remains of Gastropods

1. Wetlands

Here at the southern end of San Francisco Bay, tall grasses and other slender plants thrive around the edges of our often-salty marshes.

2. Tall grass

Towards the end of every summer, as the grasses start to dry out, you’ll sometimes see a gleaming white jewel, shining from the top of a stem.

3. Mysterious shiny thing

And if you look closer, it becomes quite a puzzle what that might be. A chrysalis? A gall of some sort?

4. Isolated, white

But it turns out to be both simpler and stranger than that. The little jewels are actually the desiccated shells of brown garden snails, bleached by the summer sun.

5. Snails!

The common garden snail in this area is helix aspersa, the culinary snail of France, imported here in the gold-rush era by a Frenchman who intended to sell them as food. Normally, they are chestnut to ebony in color, with lighter striations.

4. At least eight

But the snails that we find in the grasses– I count at least eight in this picture –have dried up after their food sources, and have been left to sit in the sun for much longer than they would like. Seems clear enough that they climbed up the stem for a leafy snack while the plant was still green, but didn’t make it down in time.

9. Faded

7. Bleached

8. Anise

Depending how long it’s been, the shells may still be striped, faded, or fully bleached. In some cases the shell is long empty and backlit by sunlight. In others, the resident has only recently passed.

In some cases the surface luster weathers shiny like a jewel, catching your eye from a distance. And that’s how we end up with ornamented grasses, glittering with the gaunt remains of gallic gastropods.

The CO2inator

A guest project by Rich Faulhaber, contributing Evil Mad Scientist.


“Infusing unsuspecting whole fruit with gaseous CO2 in the entire Tri-State Area!

In an effort to make fruit fun for the kids, I built a carbon dioxide injector from parts in my garage with the purpose of carbonating whole fruit! With a common house water filter housing, a 16 Oz paintball CO2 canister, an old gas regulator, and some miscellaneous valves and fittings, I was able to bring this fizz fruit apparatus to life, and the kids love the results.

The principle
Carbon dioxide dissolves well in water, hence the reason you find it as the source of fizz in all your favorite soda drinks. When you open your soda and let it sit out on the counter you will find that after some period of time the soda loses its fizz and becomes “flat.” The rate at which the drink loses its fizz depends on pressure, temperature and the surface area of the liquid and the environment. Skipping the thermodynamics lecture, let me just tell you that the process works in reverse as well. To reverse this process, one needs only to have a high pressure CO2 environment, a medium to infuse (i.e., the fruit) and enough time to let the gas diffuse across the fruit skin and dissolve into the water inside. Refrigerating the fruit helps tremendously in the process as well.


Parts list

  • 16 Oz paintball cylinder (or a more proper CO2 tank if you happen to have one)
  • Gas Regulator
  • Household water filter housing
  • Some hose
  • Toggle or ball valve
  • Miscellaneous fittings to hook it all up
  • Fruit

This type of water filter housing is designed to withstand water pressures in excess of 100 psi, and it comes with two ports and an o-ring seal. These can be bought for about ten dollars at Lowes or Home Depot. Its ports are standard 3/4-inch type. Use Teflon tape (plumbers tape) on all the threads. Thread in a plug on one side and a valve on the other. I used a toggle valve with a quick disconnect to make everything easier. The hose can by any standard type rated for at least 100 psi. Small bundles are available in the plumbing section of your hardware store.

For gas handling I used an old single stage regulator. These can be quite expensive new but often times you can find deals at garage sales or in surplus stores. You don’t need anything fancy, just something to step down the pressure to something manageable– well below 100 psi. My CO2 source is a standard-issue paintball cylinder.



  1. Pre-chill the fruit in the refrigerator. Get it nice and cold. My favorites are grapes, oranges and blueberries. However, just about any fruit with a large water content will work.

  2. Open the house water filter by unscrewing the lid. Place your cold fruit inside.

  3. Connect the CO2 tank to your water filter housing. This is where the quick disconnects come in handy.

  4. Adjust the regulator output to about 40-60 psi, the higher the better but make sure all your connections are extra tight and sealed or “it might get dangerous.” If you think you have a leak somewhere, you can apply some soapy water where you think the leak is and look for bubbles. If you see bubble just tighten until they stop forming.

  5. Start pressurizing the house filter by opening the toggle valve. On top of the water filter housing there is a pressure relief button. Depress this while you fill to get some of the residual air out.

  6. Once pressurized, shut the toggle valve and disconnect the CO2 line. You can store the unit in the fridge or somewhere out of sight.

  7. Then, you wait. Depending on the fruit, temperature, and pressure, carbonation should occur between 20-60 minutes. If you go too long at too high a pressure the skin of the fruit can burst and it will be a big mess, if you go too short and at too low of a pressure, the results will be unimpressive. Experiment with your fruit, pressure, and duration until it suits your tastes.

  8. Open the toggle valve to release the pressurized gas then unscrew the lid to the housing and enjoy your newly carbonated fruit.


And of course, the kids love the “poppy fizz” inside the fizzy fruit.

On the dwarf planets


When Pluto was “demoted” from being a planet some years ago, I thought that it was pretty stupid. After all, I had learned about our set of nine planets as a simple fact in grade school. If anything, I had expected the number of planets to grow as they were discovered, not shrink.

What’s the big deal? Why not just grandfather Pluto into the club? The principal consequence of which objects are called “planets” is how many little plastic balls go into a solar-system model kits, right?

Well, yes and no. It turns out that our solar system has a huge number of objects. Not just the sun and a handful planets, but also hundreds of thousands of other cataloged objects (“minor planets”), the vast majority of which are now classified as small solar system bodies. These include most of the main-belt asteroids, comets, centaurs, trojans, kuiper-belt objects, scattered-disc objects, and other trans-neptunian objects. And, we will discover more.

Today Pluto, like Ceres, is proudly known as one of our five wonderful dwarf planets.

What distinguishes these dwarf planets from their larger and more familiar cousins? An intuitive and powerful discriminator: Simply put, planets are out there orbiting on their own, while dwarf planets are found in belts of objects that share the same orbit. Putting this in mathematical terms, there’s a stark difference between our eight planets– which dominate their orbital neighborhoods –and our five known dwarf planets, which at best make up mere fractions of their respective belts. Now that we’ve recognized the difference between major planets and dwarf planets, it’s clear as day which group Pluto belongs to.

And, despite poor Pluto, the minor shame of having “lost” one of our planets seems more than made up by the discovery in 2003 of Eris– a dwarf planet both larger and (usually) more distant than Pluto. Already, some dozens of other dwarf planet candidates have been identified, and there are countless others yet undiscovered.

The simple fact is that we live in an exciting time of discovery. While it may feel natural in a sense to enshrine an immutable list of “the planets,” it is instead our humble duty as scientists to accept that we don’t — and almost certainly never will –know everything.

Another use for used inner tubes

Tree staking 3

Even after one too many flats, a used bike inner tube has plenty of uses. One more to add to the list: it can be used as a cushion between a tree trunk and a staking wire.

Tree staking 1

Cut the valve section out and cut the tube in half. For extra padding, use a double layer of tubing by pulling a section of tube through itself.

Tree staking 2

One regular bike tube makes two generously sized padding pieces, even after doubling them over. You’re ready to thread your wire through and stake up your tree!

You can also trim off a few pieces to make bike tube rubber bands.

Evil Mad Scientist Laboratories: Year 4


Happy birthday to us! Evil Mad Scientist Laboratories has now been around for four years. We’ve collected some interesting projects from this past year to celebrate.

Microcontroller and Electronics Projects:

Tabletop Pong
Tabletop Pong

Moving from breadboard to protoboard

Revenge of the Cherry Tomatoes

drink making unit
Drink making unit

pin 1
Finding pin 1

xmega - 2
Say hello to xmega

Adding a Chronodot to Peggy 2

Meggy Twitter Reader
Meggy Jr RGB Twitter Reader

twisted wire bundle
Twisted Wire Bundles

LED graph
Some thoughts on throwies

rovin pumpkin
Rovin’ pumpkin

ADXL335 - 10
Accelerometer with an AVR (updated)

LEDcalc - 20
Wallet-size LED Resistance Calculator


seeing magnetic fields
Seeing Magnetic Fields

Ice Spikes
Ice Spikes

opposition effect in clover
Opposition effect

Kitchen Science 18
Litmus Candy

Beans day five
Gibberellic Acid and Giantism in Sprouts

Simple LED Projects:

fake seven segment display
Fake seven segment display

LED-lit sea urchin
LED-lit sea urchins

Edge Lit Cards
Refining edge-lit cards

Food Hacking:

Ice Cream Gyoza -13
Ice Cream Gyoza

Lemon Pickle
Lemon Pickle

The array

coffee bean cooler
DIY coffee bean cooler

Marmalade 30
Marmalade: easier than it looks

AtomicCookies 7
Atomic Cookies

asteroids cookies
Asteroids (the edible kind)

Crunchy Frogs01
Crunchy Frog

Kit Projects:

Bulbdial Clock Kit

Peggy 2LE

LED Hanukkah Menorah Kit

Larson Scanner
Larson Scanner

D12 bag8
Handbag of Holding Kits

Crafty Projects:

arecibo 2
SETI Scarf

scrap acrylic
Scrap acrylic shelf

24 hour tombstones

ipad 3
iPad lap stand

Custom iron ons 10
Custom iron-on techniques

Geek Design:


Typographic Coasters
Typgraphical Character Coasters

Ornamental Components 08
Ornamental Components

Cat String 6
Radio controlled string

Bookend - 9
Bookends for physics geeks

Lego business cards-2
Lego Business Cards

Tie Stools2
Portable Stools

And, don’t forget, you can win a Peggy 2 or one of 13 other prizes in our clock
concept contest
, going on this week.