Why do leaves change color in the fall?

Most of the spectacular colors of autumn have been in the leaves all summer, however they were “covered up” by the dominant green of the chlorophyl. As weather cools, and shorter days settle in, the chlorophyll begins to break down, revealing new and varied color pigments.The brightest colors are seen when late summer is dry, and autumn has bright sunny days and cool nights.

Click on the image and print out this handy reference to learn the chemistry of Autumn Leaves. (Be sure to choose “size to fit” when printing.)


Robot Reference Guide

There’s something about robots that people connect to. I knew as soon as I left the theater after watching Star Wars that I would someday have my own R2-D2, (which I now do!) So I decided to ask the followers of my Facebook Page to tell me their favorite robot, and I got a huge response. Below are some of the favorites, and the approximate time that they made their first appearance. I included cyborgs (robotically modified humans) as well as some real robots that were mentioned. Thanks to all that posted! Click the image or links for a larger view. What’s your favorite robot? Did I miss any? Comment here or, even better, on my Facebook Page.

Larger Image (1794X1197)

Poster Size (10,800X7200)


Who Wrote The Bill Nye Theme Music?


In an elementary school in a Boston suburb, a group of third graders enters a classroom after lunch. The teacher is loading a DVD into her laptop hooked up to a projector emerging from the ceiling. “What are we watching?’ asked one student as he sat down with a thud.

“It’s a Bill Nye video,” she responded. What happened next was remarkable; it was as if a part of their 8 year old brain had been triggered by an electrical probe and they immediately began chanting, “Bill Nye the Science Guy” in a familiar melody while moving their body to a non-existent house beat. Just days later, I heard that same familiar tune emanating as a ring tone from the cellphone of a good friend, except he’s 25. It turns out most people I know recall at least part of the theme song for, “Bill Nye The Science Guy,” and they aren’t afraid to sing it. The hugely popular children’s science show has not aired an original episode in, get this, almost 15 years. But the show, and perhaps even more so, the theme music, lives on. Take a listen:

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Few shows have managed to have an epic theme song that stands the test of time; think Gilligan’s Island, The Brady Bunch, Friends. But if there was a Hall of Fame for theme songs, an almost certain inductee would be the theme to “Bill Nye The Science Guy.” So who wrote the music? Who’s voice chants, “Bill! Bill! Bill!” and how did a children’s science show end up with such a funky, off the wall theme? It turns out the man with the answers is a music writer, and former math teacher, named Mike Greene. He’s the guy who wrote and scored the theme into the conscience of young scientists around the world. I asked Mike when the last time was that he heard the theme. “It’s been months.” So we took a listen.

Bob:  So, as you’re listening to the theme, what is going through your head?

Mike:  [laughs] You know, I always liked that song. I still enjoy listening to it. It’s lucky that, in many ways, the song holds up because there are a lot of times that you do a theme song and the song, five or ten years later, sounds dated. Certainly you can tell that it wasn’t written today. But it’s not embarrassing. There was nobody who didn’t like Bill Nye the Science Guy. It’s one of those things that just kind of brings a smile to most people’s faces if I say, “Oh, yeah, I wrote the ‘Bill Nye the Science Guy’ theme.”

Bob:  Let’s go back to 1992. When you get the call, what did they tell you they were looking for? What kind of guidance did you get?

Mike:  The thing that they told me was they did not want it to sounds like a kid’s theme song. They didn’t want it to be safe, basically. They didn’t want to make it sound like stuff that’s already been done. They wanted it to be something that was adventurous and a little bit more daring than what a theme song, at that time, would be. It was much more common to have a song that would be like, [singing] ‘”Bill Nye’s gonna teach you some science.” Something that’s a little bit cheesier. They wanted to go as far away from cheesy or safe as they could get.

Bob:  So how did you end up approaching the theme with that kind of guidance?

Mike:  Well I’ve done tons of dance beats and bass lines. So, coming up with that was fairly easy. But you know what? Now that I think about it, the first thing I came up with, I think, might have been the main melody, [sings] “Bill Nye the Science Guy.”  I started thinking of [the band] Oingo Boingo. I had that in my head. The melody sounds like something that Danny Elfman from “Oingo Boingo” would sing. The little twirl on the [sings] “Science Guy.” I thought that sounded kind of Oingo Boingo‑ish.

Later I thought what might be kind of cool would be a guitar part.  Kinda rocky, but with a weird bizarre melody.   So I started riffing on guitar until I came up with this one line and recorded it onto my sampler.   A sampler lets you play recordings back on your keyboard, so whenever I hit that one key, it plays the guitar riff.

Bob:  Who sings the theme?

Mike: [laughs] It’s actually me. I used my voice for the first demo to send to the producers, Jim and Erren. After they approved it, I hired singers because I wanted to make it better.   I hired a guy to sing it who sounded pretty cool.  He had like a rock‑and‑roll kind of voice, so it sounded pretty slick.   Then as another option, I hired a girl to sing it to give it a bit more R&B kind of sound.    Then I sent those versions to Jim and Erren, and they said, “Why have you got them on it?   We want your voice.   It’s funnier.”    I thought, “My voice is funnier???   Good thing I’m not touchy about my singing!”  [laughs]   So we kept my voice on there.

The woman who says, “Science rules” and “Inertia is a property of matter” is a very talented actress and voiceover artist named Leslie Wilson.   I was told at the time that Bill wanted to replace her with his voice, because he thought it was weird in the open that he was mouthing her words, but I guess everybody else liked it as is.  Definitely sounds better with her voice.

Bob:  So who is the voice behind the famous, “Bill, Bill, Bill”

Mike:   Believe it or not, those are rappers.    I can’t name them, because it was against their contract to do outside things without permission from their record company.    It was kinda funny, because they were in my studio one day to record a song.   I was working on the Nye theme as they walked in and I told them, “Hey, do me a favor and go in the booth and chant ‘Bill, Bill, Bill’ over and over again.”   They had no idea what it was for, but they’re cool, so they did.   It sounded great, so that’s the version we kept.   The show didn’t air until a year later, so it wasn’t until then that they understood what this was really for.

Bob:  Have you connected with Bill Nye and chatted about the theme at all?

Mike:  We’ve had short little conversations about the theme. I run into Bill every once in a while because he lives in Studio City which is where I live as well. We run into each other about once every year, once every two years or so. There’s a funny video on YouTube of him, where I guess somebody in the audience asked him to sing the theme song or something like that. I can’t remember exactly what his response is but it’s kind of funny because he says, “Well, you know, that’s not me singing the theme song. You wouldn’t ask the stars of ‘Bonanza’ to sing the theme song of ‘Bonanza’.”

One time I flew up to Seattle for a couple of days to meet everybody and that’s the first time I met Bill. I remember one comment with Bill that I thought was pretty cool. He said, “All we want to do is change the world.”   I must say, I think he succeeded.

BONUS AUDIO! - Turns out Bill Nye The Science Guy was translated into Chinese. Listen to the Chinese version of the theme song: Beer, Beer, Beer!

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The Giant Dry Ice Bubble Sphere

If you’ve got some dry ice, why not gather friends and family and try your hand at making a large dry ice ghost bubble?This is especially fun at Halloween. Who knows? Maybe you will see your future inside the Ghostly Sphere.


  • Medium size bowl with a rim
  • Small bowl
  • Liquid soap
  • 20 inch by 2 inch strip of absorbent cloth (cut up t-shirts work great)
  • Warm Water
  • Dry Ice – Available at some grocery stores and ice suppliers

CAUTION!: NEVER touch dry ice with your bare hands.

Always wear thick gloves and keep away from children.

NEVER place dry ice in a completely enclosed container.


Fill each bowl halfway with water. In the small bowl, add a good squirt of liquid soap (we like Dawn Concentrate) and stir it up.

Get the rim of the larger bowl wet with regular water using your fingers.

Add the dry ice to the large bowl. Admire the sights and sounds of bubbling dry ice.Now the tricky part, dip the cloth into the soapy water to get it wet but not dripping wet. Pull the cloth strip so that it is taut and pass it across the entire rim of the medium bowl to create a soap bubble “skin” over the bowl. It may take several tries – don’t give up!


Once you get it, the bubble will expand as gas is released and it will rise to create your own ghost bubble sphere. After the soap gets into the water with the dry ice, you are treated to soap bubbles filled with dry ice mist!

Don’t worry about your bubble popping. We think that’s the coolest part!



Make Some Ghost Bubbles!

If you want to make any day better, perhaps the easiest way is to add bubbles to it. We have seen lots of different kinds of bubbles: big bubbles, small bubbles, bubbles that don’t pop, even colored bubbles. But my personal favorite is Ghost Bubbles. They’re not that hard to make and they are great fun to explore…especially at Halloween:


  • A large plastic container with a wide mouth
  • A rubber sink sprayer designed to attach to a faucet with the sprayer cut off/removed. (regular wide tubing, 1 cm or wider will work as well)
  • Small bowl of bubble solution. CLICK HERE for a recipe.
  • Warm Water
  • Dry Ice – Available at some grocery stores and ice suppliers
  • A glove made of fuzzy fibers.

CAUTION!: NEVER touch dry ice with your bare hands.
Always wear thick gloves and keep away from children.
NEVER place dry ice in a completely enclosed container.


  • Carefully drill a hole towards the top of the container that is just wide enough to fit the tube.
  • Fit the tube into the opening with the wide (faucet end) out as shown in the top picture and secure with tape if needed.
  • Fill the container with warm water about 1/4 full.
  • Drop several pieces of dry ice into the water and cap the container loosely. Dry ice mist should now be coming out of the tube.
  • Dip the end of the tube into the bubble solution and make ghost bubbles! If the mist is coming out too fast, loosen the container cap to adjust the flow.



  1. Try holding Ghost Bubbles with a fuzzy glove such as a wool glove. With some practice, you can toss and bounce the bubble.
  2. Allow the bubbles to fall onto a fuzzy surface, such as a towel. Try rolling them around by lifting different ends of the towel. Fuzzy surfaces keep the bubble from easily popping because they spread out the amount of pressure on the surface of the bubble, and keep it from touching a surface that would absorb the moisture and dry out the bubble, causing it to pop.


Every soap bubble is made of a film that has 3 layers: Soap, then Water, then Soap. Because of the way that soap molecules are arranged, and the way they attract and repel from each other and the water, the soap creates bonds that give the water additional strength, and allow them  to last much longer. The dry ice mist is a combination of water vapor and carbon dioxide gas from the dry ice. Because carbon dioxide is heavier than air, dry ice mist will always flow downward.



The Ultimate Bubble Solution

Bubbles may very well be the world’s first toy. From sea foam, to hand soap, to those bubbles you blow in your milk, it seems bubbles are part of our daily life. Soap bubbles way be the most fun off all bubbles and they are an inexpensive and limitless way to explore our bubbly world.

For years bubbleologists have perfected the solution for the longest-lasting and most durable bubbles. Perhaps the person who has studied the science of bubbles the most, is  Keith Michael Johnson. And he recently shared his unlikely TOP-SECRET formula for the best bubble solution…

You will need:

  • Water – many bubble enthusiasts are convinced that distilled water makes the best bubbles
  • Liquid dish soap. Dawn dish soap has always been a favorite
  • SurgiLube (available at medical supply stores) or K-Y Jelly (available at pharmacies)
  • A clean plastic bottle to hold your bubble solution

What to do:

Simply pour all three ingredients into the bottle in the following ratio:

  • 12 parts water
  • 1 part dish soap
  • 1/2 part SurgiLube

For example you would start with 12 ounces of water, add 1 ounce of liquid dish soap, and 1/2 ounce of SurgiLube. You can increase the amounts equally to make more.

  1. Shake the ingredients up well (don’t worry, the bubbles  from shaking will go away)
  2. For best results, allow the bubble solution to sit overnight. Then you’re ready to go!

How do bubbles work?

Every soap bubble is made of a film that has 3 layers: Soap, then Water, then Soap. Because of the way that soap molecules are arranged, and the way they attract and repel from each other and the water, the soap creates bonds that give the water additional strength, and allow them them to last much longer. Bubbles will always be round when they are floating because the elastic nature of the soap bubbles allows air pressure to push equally on the entire surface of the bubble forming a sphere.

Bubble fun:

  • You do not need bubble wands from the store to make bubbles. Simply dipping your hand in bubble solution and making a circle with your fingers makes a great bubble wand. Straws, plastic strawberry containers, fly swatters, and aquarium nets make great bubble wands.
  • To make foamy bubbles, use a rubber band to secure a piece on cotton cloth over the end of a small section of plastic pipe. Soak the cloth in the bubble solution and blow from the other end.
  • Pour a small amount of bubble solution onto a clean counter top and spread it out. Use a straw to blow a dome-bubble on the counter top. Keep blowing into the bubble to make it bigger and bigger. With some practice, you can get a bubble dome as big as a dinner plate!

Oreo Cookie Moon Phases

I’ve always been a fan of science activities that you can eat. One of my favorites that I have been using for years is the Oreo Cookie Moon Phases activity. It’s almost as if Oreo cookies were made for this lesson, and it’s a great way to see how well students can match a moon phase name with a moon phase appearance.

You will need:

  • An Oreo cookie for each student
  • A piece of paper with a moon phase written on it for each student (I omit “Full moon” – that’s just too easy)
  • A popsicle stick or other tool for scraping the frosting

What to do:

  1. Fold up each piece of paper with the moon phases written on it and hand one to each student as they enter the room – tell them not to open it yet. I will often have them store it in their shoe. They think that’s funny, and they won’t lose it.
  2. Demonstrate the proper way to slowly twist an Oreo to maximize the amount of frosting on one side when you separate the halves. (practice yourself, it can be tricky)
  3. Give each student a cookie and have them twist the halves open. Hopefully most will the frosting will be on one side or the other. They can always transfer frosting if needed.
  4. Have the student retrieve their moon phases while you hand out the craft sticks.
  5. Recreate the given phase in frosting!

I will usually tour the room and once they show me that they’ve got the phase right, they can eat the moon! Of course be aware of food allergies and such. If you try this out, let me know how it goes!

Science On The Set of Little Fockers

Daisy Tahan and Colin Baiocchi in Little Fockers

One of the best parts of sharing experiments on this website is hearing back from people that get to try them out. I was happy to recently find out that the young actors that appear in the movie, The Little Fockers were fans of sciencebob.com. Even famous child actors have to go to school every day, so film and TV productions set up a special room or trailer that gets used as the classroom while the filming is going on. A teacher is on the movie set every day to teach lessons in between filming scenes. While this film is targeted for adults, we were happy that some great science lessons were going on behind the scenes with the young actors. The lessons were led an amazing teacher named Maura who enjoys exploring hands on science and bringing learning to life. Maura was kind enough to contact me and send us some behind-the scenes photos from the set of the movie.

Daisy Tahan plays Samantha Focker in the film. She’s been acting since she was just 4 years old. In this picture she is trying out our experiment titled “The Fizz Inflator” which allows you to inflate a balloon using only the power of chemistry. As you can see it was quite a success for Daisy.  To try out the experiment yourself, just click HERE.

Daisy also experiment with non-newtonian fluids when she created oobleck using corn starch and water. In the right combination, these two ingredients make very unique goo that can act like both a solid and a liquid. (If Daisy’s hands look a little blue in any scenes of the movie, now you will know why.) If you want to try making a little gooey oobleck yourself, it’s easy. You can find all the instructions HERE.

Daisy and fellow actor Colin Baiocchi, who plays Henry Focker in the movie, confirm what famous scientist Archimedes observed hundreds of years ago regarding the displacement of water when an object is placed in it. The graduated cylinder with the green water allowed them to measure how much the water was raised when different objects were placed in it.

Maura reports the two actors also got to try out our film canister rockets. We’re happy that our experiments were able to provide some fun and learning on a backlot in Hollywood as much as they are in classrooms and living rooms around the world. Thanks again, Maura!

We’d love to see YOUR pictures of our experiments in action. We may post them right here on our blog. You can email them to comment@sciencebob.com. Happy exploring!

Medical Myths from Dr. Oz Explained

Was Everything Your Mother Told You Wrong?

The Dr. Oz Show recently took on the topic of whether or not the common guidance that your mother gave you was actually wrapped in myth. You can check out the segment HERE. I was happy to get the call to try to add some visual demonstrations to bring home the concepts of these myths. The segment was a lot of fun, and everyone a the show is amazing. Despite all the big demos, there was some interesting medical science discussed. I spoke with some audience members after the show that had a lot of questions about the myths. While I’m obviously am not a doctor, I thought I’d share my explanation of some of the science behind these interesting myths from the show:

MYTH #1 Eating Too Much Sugar Will Make You Hyper
It seems to be a common idea that when children eat a lot of sugar they quickly become active and energetic. The demonstration with the celery and the gummy bear shows just how much energy can be released from foods. It also showed that, without a doubt, sugary foods pack quite a punch when it comes to releasing energy. Here is where the myth comes in: simply eating sugar does not make you hyperactive. It just gives you a source of energy to tap into. You could eat a candy bar and use that energy to run around the block, but it will not MAKE you want to run around the block. If you decided to read a book, the energy from the candy bar would be stored as fat. As Dr. Oz  pointed out, kids tend to eat a lot of sugary snacks in environments that would get them excited and give them reason to run around and be active such as a birthday party, Halloween, or just having a friend over after school.

MYTH #2 Breathing in Helium Will Kill Brain Cells
This was a fun demo. The audience was laughing so much from Dr. Ozs’ Barry White voice, I’m not sure they heard all his explanation. In case you missed it, here’s a recap: At some point in our lives, we are all likely to breathe in a balloon full of helium and enjoy the comical Daffy Duck voice that follows. When I was growing up, I was told that this was a bad idea and that brain cells were being destroyed. The good news is, breathing helium does not kill brain cells. The bad news is that breathing helium can, in fact, kill you — but not because of the helium, rather because the lack of oxygen when you inhale the helium. As you breathe in a balloon full of helium, you are not breathing in any oxygen, which your cells need –  usually we get this from the air we breathe. The lack of oxygen that comes from breathing in helium can cause fainting or even asphyxiation and death. This is especially likely if you were to breathe several balloons full of helium without getting enough oxygen in between. The bottom line; avoid breathing any gas that is not already in the air around you.

But why does your voice change with helium? Helium makes your voice sound higher pitched because helium is six times lighter than air and sound travels through helium faster than it does through air. The result is that the low sounds of your voice get “suppressed”  by the less dense helium and you hear the high tones of your voice. Our sulfur hexafluoride demo had the opposite effect; because it is more dense than air, it drowns out the higher sounds sounds and emphasizes the lower pitch (really timbre) of our voice. On a sulfur hexafluoride side-note, there is a great guy that I get my liquid nitrogen from that NEVER smiles, I mean, never. That all changed when I visited him with the tank of sulfur hexafluoride, took a breath of it from a balloon, and did my best evil laugh…we got a smile from him.

Myth #3 Bundle-Up in Cold Weather or You’ll Catch a Cold
Well this makes sense, after all they must call it a “cold” for some reason. The producers of Dr. Oz had seen talented science educator Steve Spangler make smoke rings during his appearance on Ellen and they really liked the visual. Since you catch a cold from bacteria and viruses, and NOT a cold environment, we used the smoke ring vortex generator as a way to visualize the germs that were spread out during a cough. It ultimately demonstrated that despite whether you are bundled up or not, germs that cause a cold and flu can still get to you – so wash your hands regularly with a moisturizing foam soap soap.

Myth #4 – Hydrogen Peroxide is a Good Way to Disinfect a Cut?
Before we started this demo, Dr. Oz  asked how many people in the audience have used hydrogen peroxide to clean a cut. We were both surprised to see that almost the entire audience raised their hands. Perhaps we should not be surprised, after all, it says right on the bottle that it can be used to disinfect a cut. Hydrogen peroxide works as a disinfectant by releasing oxygen when it comes in contact with an enzyme in the body called catalase. That is why putting hydrogen peroxide on an open cut will create bubbles — the bubbles  are actually filled with oxygen and in some cases that oxygen-rich environment can kill bacteria. The downside is that it can also harm healthy cells surrounding the cut. Some evidence also points to the fact that the reaction happens to fast in a cut to make much of a difference.  For that reason, hydrogen peroxide is not a good choice for disinfecting most cuts although it is used in other applications for disinfecting. The larger demonstration with the flasks showed a very fast release of oxygen from a 30% hydrogen peroxide solution (store-bought hydrogen peroxide is 3%.) During rehearsal, the flask shot foam so high into the air and it hit the lights above, and we were hoping you would do that during the show.  It turns out the bottle of hydrogen peroxide that was used during the show was slightly older and less powerful than the bottle used during rehearsal, but it was still just as messy nonetheless.

Hopefully that explains the myths a bit more. I hope you enjoyed the segment and that it made some medical and not so medical science fun to watch.

A Density Experiment You Can Drink!

Density is a fascinating and sometimes tricky idea to understand. This Drink of Density will help bring home the idea of density in liquids, not to mention it looks cool when your all done, it’s tasty, and it’s even good for you – what more could you ask for in a science activity!

You will need:

  • Juices that have different density levels. (see below for a simple explanation of density) The density of a juice is often determined by how much sugar or fruit is in it – the more sugar or fruit, the more dense the juice is. Powdered and canned juices do not work well for this experiment since they are almost entirely water. You will have to do some experimentation to find juices that are colorful and give a nice display of density, and that’s half the fun.
  • A narrow glass (the more narrow it is, the easier it is to separate the density levels)
  • Eye dropper or turkey type baster.

What to do:

  1. Before you begin, you can guess which juices you think will be more dense and form a hypothesis of how the levels of your Drink of Density will turn out. Check the number of ingredients, the sugar content, and the water content to help you out.
  2. In order to display your density levels, you will need to find out which of your juices are the most and least dense. Pour one of your juices into the narrow glass to fill it about 1 inch (2.5 cm) high. Fill a dropper with another juice and slowly drop it onto the inside of the glass so that it runs down the side of the glass. Watch the juice to see if it goes below or above the juice in there. (if it simply mixes with the juice and does not go above or below, it has the same density as the juice and you will need to move on to your next juice.
  3. Continue experimenting with other juices to determine which juices go to the bottom (more dense) and which ones go to the top (least dense.)
  4. Once you have the densities determined, start over with a clean glass and use the dropper for each level to create your final Drink of Density!

Note: In case you were wondering, the juices in the photo are (top) Tropicana Pomegranate-Blueberry, (middle) Tropicana Pure Premium Orange Juice, (bottom) Nature’s Promise White Grape (33 grams of sugar in 6.75 ounces!)

How Does It Work?:

The density of liquids demonstrates the the amount of “stuff” (atoms, mass) that are present in a particular volume of the juice. In other words, if you have cup with 200ml of plain water, and a cup with 200 ml of water that has lots of sugar dissolved in it, the cup of sugar water will be heavier even though they are the same volume of liquid – the invisible sugar molecules are dispersed in the water, making it heavier (more dense.)

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