Dr. Universe

Ask Dr. Universe – Toothpaste

Dr. Universe: How does toothpaste clean your teeth? -Lucy, 10, Pullman, WA

Dear Lucy,

If you are anything like me, every day you squeeze a little toothpaste onto your toothbrush and brush your teeth. Toothpaste gets its cleaning power from a few different ingredients.

My friend Mark Leid was happy to tell us about how they work. Leid spent part of his career teaching future dentists. He is also dean of the Washington State University College of Pharmacy and Pharmaceutical Sciences.

First, he told me the outer covering of a tooth is called enamel. It’s the hardest tissue in the whole human body—even harder than bone—and it helps with things like chewing your food.

Inside your mouth and on your teeth, there are lots of tiny living things called microorganisms. They are so small you’d probably need a microscope to see them, but they like to eat the leftover food bits that get stuck in your teeth.

As they eat those leftover bits, they also make acid. That acid can break down your enamel, which can lead to cavities or tooth decay.

“We can’t make new enamel,” Leid said. “Once our enamel is gone, it’s gone.”

That’s part of the reason it is so important to brush our teeth. When you brush your teeth with toothpaste, it helps get rid of that acid.

Leid said some ingredients that help get rid of the acid and leftover food in your teeth are called abrasives. These create scrubbing power and sometimes give the toothpaste a gritty texture. Abrasives are combinations of atoms, which are like building blocks, that come together to form something called a chemical compound.

One example is calcium carbonate, which is made up of carbon, oxygen and calcium atoms. Another is silica gel, which is made up of silicon and oxygen atoms. Some other compounds create scrubbing power, but these are two of the main ones.

Meanwhile, other toothpaste ingredients help create foaming action, such as sodium lauryl sulfates and sodium N-lauryl sarcosinate. These are the same compounds that give soaps their foamy qualities.

Take a look at the back of your toothpaste tube and see what ingredients you can find. Another ingredient you might notice is fluoride, which helps strengthen your enamel. You might also see other flavoring agents that give toothpaste its taste, like mint.

“Otherwise, it would taste pretty chalky and bitter,” Leid said.

When you brush your teeth, you are helping your mouth stay clean and healthy. In addition to brushing, flossing is also important. Floss helps remove any excess food between your teeth that might invite those acid-making bacteria.

It’s great to hear you are curious about toothpaste, Lucy. Who knows, maybe one day you will be a chemist, a dentist, a pharmacist or anything else you dream. Keep up the great brushing, keep asking great science questions and don’t forget to floss.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Touchscreens

Dr. Universe: How do touch screens work? -Nicholas, 11, Florida

Dear Nicholas,

When I got your question, I decided to do a little experiment. First, I tapped my paw on a tablet and sent a message to a friend. Next, I put on a pair of wool mittens and started typing, but the screen did not respond. Finally, I used a banana to see if I could use it to swipe the screen. It actually worked.

I wondered what exactly was going on here and decided to take our questions to my friend Praveen Sekhar. He’s an associate professor in the Washington State University School of Engineering and Computer Science.

Sekhar told me our touch screen devices use electricity to work and that different materials can impact how the electricity flows. Some materials called insulators keep electricity from flowing, such as the wool mittens. Then there are objects such as your finger or a banana that allow electricity to flow from one place to another. We call these conductors.

When your finger touches the screen, it creates a sort of pathway for electricity to flow from your finger to the device. You read that right: you have electricity in your body— from your toes to your fingers.

Sekhar said you can think of how these touch screens work sort of like a battery. If you look at a battery, you will see it has a positive charge end and a negative charge end. Electricity will start to flow if both ends are connected to your device.

A touch screen device on its own has a negative charge, he said. But once your finger connects with the touch screen it becomes positive. The electrical charges can work together to help your device work. This kind electrical ability is called capacitive technology and is found in many touch screen phones, tablets, and computers.

Sekhar also told me about another kind of touch screen. These are the kinds of touch screens we see at ATMs and in grocery stores. These screens aren’t quite as bright as your computer or phone. We call these resistive screens, and they are made of layers of glass and plastic with a chemical coating and a sheet of metal underneath them.

When you press these screens with your finger, you apply pressure to the material. Inside the material, the electrical charges start moving inside as they respond to pressure from your finger and allow the device to work.

Whether it is capacitive or resistive technology, touch screens have become part of many people’s daily lives.

With help from an adult, perhaps you can do a little investigation into touch screens, too. Collect a few small items from around the house to find out which ones are insulators and which ones are conductors.

Screens are quite fragile so you may want to use materials that will be gentle to your screen, like a cotton swab, an eraser or a banana. Touch the objects to the screen to see if they allow your device to respond. Make a list of which objects conduct, or allow electricity to pass through, and remember how electricity helps your phone do all kinds of amazing things.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Flying Squirrels

Dr. Universe: Do flying squirrels really fly? – Gwendolyn, 9
Dear Gwendolyn,
Flying squirrels may not really fly, but they do have flaps of skin on their bodies that act like parachutes and help them glide through the air.
My friend Todd Wilson told me all about it. He’s a wildlife biologist with the U.S. Forest Service in Oregon and graduate of Washington State University who researches Pacific Northwest ecosystems and the animals that call them home— including flying squirrels.
When flying squirrels are trying to avoid predators, like weasels, sometimes they will run to the top of a tree. The weasel might think the flying squirrel has nowhere else to run. That’s when the flying squirrel makes its move.
“The flying squirrel can just take off and glide,” Wilson said. “When they launch themselves from a tree, they can actually go quite a ways out, but they’re not actually flying.” 
Depending on the tree, flying squirrels can sometimes glide for hundreds of feet. As they glide, they can use their tail to steer around and between other trees.
Flying squirrels are not only amazing to watch, but they also play an important part in forest ecosystems.
While other tree squirrels eat a lot of nuts or seeds from tree cones, a big part of a flying squirrel’s diet is something different. They eat an organism called fungi that live under the soil.
“Flying squirrels eat the fruits of the fungi in the forest—if the fruit is above ground, it is called a mushroom. If the fruit is below ground, we call it a truffle. Flying squirrels eat a lot of mushrooms and truffles, and then pass them through their digestive system,” Wilson said.
Flying squirrels help spread the fungi around the forest through their, well, poop. As new fungi grow, they suck up nutrients from the soil and pass on those nutrients to trees. In exchange, the trees give fungi some sugars that help the fungi grow.   
While flying squirrels play a big part in our forests, we rarely see them during the day. They are nocturnal, or active at night. But sometimes we can hear them.
They are pretty quiet compared to other squirrels, but they occasionally make a chittering sound as they meet up with other flying squirrels. We sometimes hear a big slap when they land on a tree. After all, there’s a lot of power and speed in that glide. 
When flying squirrels glide during the night, they may pass other nocturnal neighbors in the sky, like bats.
Of all the thousands of mammal species on our planets, bats are the only mammals that can truly fly.
You know, the living things in the forest are linked together in important ways. They need each other to live and grow. Humans also play a big part in our forest ecosystems.
Can you think of ways humans are connected to the forest? Maybe you can even find some connections between you and a flying squirrel. Share your answers and ideas with us some time at Dr.Universe@wsu.edu.
Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Dogs’ and Cats’ Behavior

Dr. Universe: Why do dogs and cats spin around before they sit down? – Antonio, 10, Richmond, Va.

Dear Antonio,

That’s a great observation about cats and dogs. Even I wasn’t sure why cats spin around before they sit down, so I took your question to my friend Dr. Jessica Bell.

She is a veterinarian at the Washington State University Veterinary Teaching Hospital and has seen quite a few cats and dogs walk in a little circle before they sit down.

“It’s a common thing we observe as veterinarians, but we can’t talk to cats and dogs and ask them ‘why,’” she said. “From a behavioral standpoint, it probably stems back to their wild instinct.”

An instinct is a behavior that animals don’t have to learn. They are born with this behavior, and it often helps them survive in the world.

When cats and dogs spin in a full-circle, they have a chance to observe their environment. They might even spin in circles a few times to be certain the spot where they want to sit is safe.

They are likely keeping their eyes out for any danger, such as predators. This behavior was especially important when felines and canines lived in the wild. While a lot of cats and dogs may live in homes with humans these days, they never lost this instinct.

You may have also noticed that sometimes cats and dogs sniff around as they get ready to lie down. Both senses of sight and smell can help these animals make sure the coast is clear. Bell also told me that once the animal knows a space is safe, it will often return to the same spot.

“They often position themselves in the same place on their bed every time or face the same direction,” she said.

While that may be the more scientific answer to your question, she also offered another idea.

“I think many dogs and cats are just finding a good, comfy, fluffy spot to lay down with just the right depth and cushiness,” she said.

Finding a good place to rest can also be helpful for dogs who are getting a bit older. For instance, dogs that have arthritis, a condition where the joints get stiff or swollen, will often walk in a slow circle before they lie down.

If you keep your eye out, you may notice that other animals, such as horses or birds, walk in a circle before they sit, too. You might see birds getting comfortable in their nests or a birdhouse. They even flip around their feathers and move different parts of their nest to get everything just right before they settle in.

You know, a lot of veterinarians pay close attention to animal behavior and ask a lot of questions about it as they take care of our pets. If you keep up the great observations and continue to ask questions, you might just help us learn more about the amazing animals on our planet one day.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Stinky Cheeses

Dear Dr. Universe: Why do some cheeses stink? – Cody, 11
Dear Cody,
When you take a whiff of stinky cheese, that smell is coming from one of its very important ingredients: microorganisms. 
Microorganisms are so small, you’d need a microscope to see them, but sometimes they give off a big stink. To find out more about stinky cheese, I talked to my friend Minto Michael.
Michael is a professor of dairy science at Washington State University and told me microorganisms do a few different jobs to help make cheese. These microorganisms can consist of bacteria, yeasts or molds, but bacteria are the most important in cheesemaking.
When cheesemakers add lactic acid bacteria to milk, the bacteria help get the milk ready for another ingredient called rennet, an enzyme. This enzyme helps turn the milk from a liquid state into more of a solid that will become cheese.
While the bacteria may do a lot of work to help make the cheese, there are benefits to the job.  
“These bacteria eat up the milk sugar, milk proteins and milk fat, so that they can get energy and multiply,” he said.
As the bacteria eat to get energy, they can also produce a stinky gas. The gas is made up of molecules. Some of these molecules that include ammonia or sulfur compounds are responsible for the smell in a lot of stinky cheese.  
When certain molecules come in contact with receptors in your nose, your brain helps you figure out what you are smelling. Maybe your brain tells you to stay away from stinky cheese—or maybe it makes you want to try it.   
Michael told me about some of the most smelly, or pungent, cheeses. One of them is called Roquefort cheese. This is a kind of a blue cheese that gets its odor from a mold named Penicillium roqueforti. If we looked at it under a microscope, we might notice that it is a kind of paint-brush shape. Penicillium in Latin means “painter’s brush.”
Meanwhile, a different kind of bacteria called Brevibacterium linens is responsible for the smell and flavor of some other blue cheeses. Brevibacterium linens is not only the bacteria responsible for one of the smelliest cheeses on the planet called Époisses, but is also the same bacteria that makes the smell of human body odor. 
When people make cheese, sometimes they will let it age for a while. For some cheeses it may be two months or even two years before they are eaten. As the cheese ages, the aromas often start to get stronger and stronger. Of course, not all microorganisms produce gases that are stinky.
One of my favorite non-stinky cheese varieties was developed at Washington State University. It’s a sharp white cheddar called Cougar Gold that comes in a can.
After investigating your question, I was curious to find out what kind of bacteria is in this cheese. It turns out the answer is a top-secret recipe even I’ll never know. But it’s no secret that it tastes and smells delicious.
Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Bird Migrations

Dr. Universe, How do birds know where to migrate? – Jasmine, 10, Gainesville, Florida 

Dear Jasmine,  

There are all kinds of different birds on our planet, and they migrate to different places.

My friend Heather Watts, a researcher at Washington State University, is really curious about bird migration and told me more about how birds know where to go.  

She said there are some birds that make a round-trip flight when they migrate. For instance, the bar-tailed godwit will make long flights between Alaska and New Zealand, traveling more than 7000 miles without stopping.  

Meanwhile, a blue grouse makes a much shorter round-trip flight. It migrates less than a quarter of a mile.   

Scientists think that some birds may know where to go because of a kind of program that’s built into a bird’s DNA. It’s sort of like being born with a set of directions they know how to use. This genetic information is passed down from bird grandparents to bird parents to the offspring.  

“What we think a lot of birds do the very first time they migrate is use a program that tells them what direction to go and how far to go in that direction,” Watts said. 

On a bird’s first migration, it may also follow other birds. The next migration season, the bird may be able to use clues from the environment to find its destination.   

There’s another kind of migration that has scientists, like Watts, asking lots of big questions. It turns out there are actually birds that do not migrate to the same location every year.  

We might see birds like pine siskins breeding in California one year and then in Canada the next year.

“We don’t know as much about this type of migration,” Watts said. “It’s really hard because we don’t know where the birds are going to be and when they are going to be there.”  

Watts and her lab are studying the pine siskins to learn more about the ways these types of nomadic birds migrate and what might be going on behind that behavior.  

Different birds may migrate in different ways, but they will often migrate for similar reasons. While there are some unsolved mysteries around migration, one thing we do know is that migration is really important for helping birds find what they need to reproduce and survive.  

You know, it can be quite fun to watch all the different birds in our neighborhoods. Here’s a science challenge for you: the next time you go for a walk or gaze out the window, see what birds you can spot. With help from a grown-up, see if you can find the name of the bird online or at the library. Finally, do a little research to find out how it migrates and discover the journey your bird takes.  

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Mushroom Rings

Dr. Universe: Why do mushrooms grow in rings? We have a lot of giant ones in our yard right now! – Layne, 8, Spokane 
Dear Layne,
When you see a ring of mushrooms, it’s likely they are exploring for food under the ground.    
Giant mushrooms in your backyard are not animals or plants. They are part of another class of living organisms called fungi. But like you and me, they do need food to survive.
That’s what I found out from my friend David Wheeler, an assistant professor at Washington State University, who knows a lot about fungi.
He said the mushrooms are just one part of fungi. The other part that explores the soil for food actually lives under the soil.
This part is called the mycelium and looks a bit like cobwebs or stretched out cotton candy.
Mycelium help the fungi explore different spaces and absorb nutrients from things like dead logs or decaying leaves.
Wheeler said we might think about the way a mushroom ring forms, including how the mycelium spreads out, as if it were a ripple in a pond.
Just as ripple starts with a raindrop or stone, a mushroom ring begins with a tiny spore.
To help grow new fungi, mushrooms will release spores, which are sort of like seeds. After a mushroom releases the spores, they float through the air and when they land in soil, the mycelium begins to grow beneath it.
It starts expanding outward from the place where the spore landed. This allows the fungi to cover a lot of ground on the hunt for food.
It’s at the outer edge of the mycelium where we see the ring of mushrooms grow up from the soil.  
I found out there are some mushroom rings that have been around for a really long time. For instance, one mushroom ring in France has been around almost 700 years.
As the fungi spread out in search of food, the ring got wider and wider. Now, the ring is almost a half mile wide. You would have to walk the length of eight football fields to get from one side to the other.
Even though fungi don’t have legs, they sure know how to go the distance. And a big part of that has to do with their mycelium.
“Every step you take in the forest, under one foot—even one kid foot—there could be lots of cells of mycelium,” Wheeler said.
Wheeler also told me that fungi sometimes compete for food. If you look at the mushroom ring in your backyard, you may notice something unusual about the grass around it.
Sometimes grass inside the ring may be brown, and the grass inside the ring might be bright green. That’s because fungi and grass both like to eat the same thing.
They are both after the nutrients in the soil. But as the fungi grow, they can steal nutrients away faster than the grass can handle. 
You know, it’s great to hear you are observing nature in your own backyard. It’s a good reminder that we can find science questions almost anywhere in this big, wide world—even in a ring of mushrooms.
Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Foggy Mirrors

Dr. Universe: Why do mirrors fog up when you breathe on them? -Zinnia, 7, Richmond, Virginia 

Dear Zinnia,

That’s a great observation. When you breathe out, you let a couple of different things into the air.

Not only do you breathe out carbon dioxide, but you also breathe out teeny tiny droplets of water. These water droplets are so small we can’t see them with our eyes.

Scientists actually have a name for these little droplets of water in the air: water vapor. You may remember from our question about the states of matter that there are all kinds of different gases, liquids and solids in our world. Water vapor is a kind of gas.

My friend Cigdem Capan, a physics instructor at Washington State University, said one big factor that can help water move between these different states of matter is temperature.

When you breathe on a mirror, you are helping water move from a gas state to a liquid state. The surface of the mirror is a lot colder than the water vapor that comes from your warm human body. If you breathe on a mirror, you can easily feel that heat releasing into the air.

As water vapor in your breath reaches the mirror’s cool surface, the vapor droplets come together to form a liquid. When this happens, you can see thousands of super tiny liquid droplets form on the mirror: the fog.

Scientists also call this transition from a gas to a liquid, condensation. It’s the same process that helps form big, fluffy clouds in the sky, tiny drops of morning dew, or the water droplets on the outside of your cool water glass.

“If you are wearing eyeglasses and you are wearing a face mask, you can also see the glass fog up,” Capan said.

That’s condensation, too. While you may not always be able to see the water vapor from your breath, when the temperatures drop it is a bit easier to observe this condensation in action.

It’s been pretty cold here in the Northwest, so I’ve noticed this happen when I go outdoors. As we breathe into the chilly air, the warm water vapor condenses into tiny droplets of liquid water—and even some solid water, or ice—that form a kind of miniature cloud. It’s pretty fun to watch.

Whether you fog up the cool air, a window or your glasses, you may have also noticed that the moisture doesn’t stick around forever.

Try breathing on the surface of a glass mirror or windowpane and watch what happens. Eventually, the liquid droplets disappear from the mirror. Why do you think that might be?

Share your ideas with your friends or family, and see if you can work together to figure out where those water droplets go. If you need a hint, do a little bit of research on how puddles dry up or investigate the water cycle on our planet. Tell us what you discover at Dr.Universe@wsu.edu

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Shadows

Dr. Universe: Can a shadow make a shadow? – Aven, 7, Palouse, WA

Dear Aven,

When we look around our world, we can find all kinds of shadows. One way we can explore the answer to your shadow question is with a little experiment.

My friend Anya Rasmussen, a physics professor at Washington State University, told me all about it.

First, you will need to cast your shadow on a wall. Rasmussen reminded me shadows form when an object—such as your body— blocks light and keeps the rays from reaching a surface—like a wall.

To see how this works, you can ask a grown-up or friend to shine a flashlight or a lamp behind you and onto the wall.

You can also take some time to see how the shape and length of your shadow change as you move closer or farther from the wall.

“If you want to see if your shadow casts shadows, now shine a light on your shadow,” Rasmussen said.

Point another flashlight at the shadow, then take a few moments to observe what happens. Alright, it’s almost time to reveal the answer, so if you want to experiment, come back and finish reading this after you try it out.

If you have continued reading, here is a spoiler alert: A shadow can’t make a shadow. Unlike you and me, a shadow cannot reflect or absorb light. It can’t block rays of light and keep that light from reaching a surface.

While you’ve got your flashlight out, there are a few other ways you can play with light and shadows, Rasmussen said.

Perhaps you’ve noticed that sometimes two shadows will come from one object. If you have two flashlights or two light sources, you could try to create multiple shadows by shining the light on an object from two different angles. Maybe you can even see what happens when you use three flashlights.

If you are anything like me, you might also be surprised to learn not all shadows are black. Rasmussen said that if we experimented with red, blue and green lightbulbs we could make shadows in different colors.

We can make small shadows or big shadows. Even our enormous Earth makes a shadow. As the moon passes through Earth’s shadow, it creates a lunar eclipse.

Light and shadows are not only an important part of understanding physics, but they are also a big part of creating art and telling stories, Rasmussen said.

When we look at paintings from impressionist artists like Claude Monet and Edouard Manet, we can see how they paid a lot of attention to these two important elements. After all, shadows and light go hand in hand.

After you’ve finished experimenting, see how many shadows you can spot around your home or around the neighborhood. Perhaps you can even sketch a few different shadowy shapes out on a piece of paper.

Who knows, maybe one day you’ll be a scientist or an artist—maybe you’ll even be both. You are well on your way.

Dr. Universedoc

Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Rainbows in Oil

Dr. Universe: Why does oil on the street look like a rainbow? -Jorgos, 10, Bothell, WA

Dear Jorgos,

When it rains, sometimes we can see oil on the street rise to the top of puddles and spread out into a rainbow of colors.

One of the main reasons we see color is because of light, said my friend Cigdem Capan, a physics instructor at Washington State University.

She reminded me that when our eyes sense colors, we can trace those colors back to different wavelengths of light. Perhaps you can make some waves in the air with your hand. Make small, tight waves. Now make a big, wide waves.

The light waves that help us see color are a lot smaller than any wave we can make with our hand. According to our friends at the National Oceanic and Atmospheric Administration, blue or violet wavelength is about 125 times smaller than the width of a human hair.

When these light waves reflect, or bounce, off different surfaces such as an oily puddle, our eyes and brain work together to help translate the information into color.

It turns out there are two places in an oily puddle where the light waves can bounce off or reflect. If you’ve ever mixed oil and water together, you know that they like to be in separate layers.

One place where the light reflects is the top of the puddle where the air meets the oil. The other place is where oil and water meet. Lightwaves have to travel a bit farther through the puddle to reflect where the oil and water meet.

Let’s say you see some purple spots in an oily puddle. You see this color because red, orange, yellow, green, and blue waves reflect off the puddle and overlap with each other in the air. When the waves overlap, they actually cancel each other out, so you can’t see them with your eyes.

But the violet waves reflect off the surface and travel in unison through the air to your eyes. As they travel, these violet wavelengths get a bit of a boost from each other, and the purple appears bright to your eyes.

The differences in the thickness of the oil can make some wavelengths reflect in unison and that is how we see not just the purple spots, but all the different colors in an oily puddle.

The colors that you see in an oily puddle are also a kind of phenomenon we call iridescence. We can see this phenomenon when we observe the outside of soap bubbles or the colorful feathers of the male peacock.

There are so many different colors in our world. Perhaps you even have a favorite one. A couple of my favorite colors are crimson and gray. No matter what colors we see in our world, remember that we can trace all of them back to waves of light.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Black Holes

Dr. Universe: How many black holes are in the galaxy and the universe?
-Krisha, 9, New Jersey

Dear Krisha,

While we can’t see black holes with our eyes, astronomers have figured out how to spot these objects in our universe.

One astronomer who is really curious about understanding black holes is my friend Sukanta Bose, a researcher at Washington State University.

First, he told me there are different kinds of black holes. Supermassive black holes can be millions to billions of times the mass of the Sun. We have a supermassive black hole in our own Milky Way galaxy called Sagittarius A*, which is pronounced as Sagittarius A-star.

Scientists think supermassive black holes may be found in the center of most large galaxies.

If you are anything like me, you might be wondering: why not just count all the different galaxies to find the number of black holes?

“Of course, we cannot see every galaxy,” Bose said. “We see many galaxies that are closer because they are brighter.”

For galaxies that are farther away, you have to use very powerful telescopes, he adds.

That also means we have to make an inference about the number of galaxies in the universe. An inference is an educated guess based on evidence and current knowledge about how things work.

Using telescopes, math and their inference skills, astronomers estimate there are hundreds of billions of galaxies and likely hundreds of billions of supermassive black holes— that’s just in the observable universe.

Bose told me there’s another kind of black hole that sometimes forms when a star dies and collapses in on itself. We call these stellar mass black holes.

The Sun is a star, but it is far too small to become a black hole. Only heavier stars make black holes. When it comes to stellar mass black holes, astronomers estimate there are ten million to a billion right here in the Milky Way galaxy.

On the hunt for these massive objects, scientists often look for different interactions among stars or gases, clues that there may be a black hole in the neighborhood.

For instance, when a black hole and a companion star are in a tight orbit, their interaction can sometimes create high energy light we can’t see, but that scientists can detect with their high-tech tools.

“When you open a new way of probing the universe, you see objects that challenge your previous wisdom or theories,” Bose said.

Bose and fellow researchers have been able to spot black holes because of a new way to detect something called gravitational waves. When two black holes collide, they can create a kind of wave that brings information to Earth about its source and helps us learn more about the universe.

It’s a bit like listening for sound waves from particular instruments in an orchestra, Bose said. But instead of picking out the sound of a cello or a flute, they are listening for gravitational waves from those colliding black holes.

Who knows, maybe one day you can help us learn more about black holes and discover ways to help astronomers count them all.

Dr. Universe

Thanks to all our kid readers who voted for this question in our recent poll. Stay tuned for future polls at askDrUniverse.wsu.edu.

Know a kid with a science question?
With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.
Submit a question

Ask Dr. Universe – Tears and Yawning

Dr. Universe: Why do we get tears when we yawn? – Ella, 8, Australia

Dear Ella,

You’re right, a lot of people get tears when they yawn. When you yawn, you actually use lot of muscles in your face. Maybe you can feel the stretch in your jaw, cheeks and eyes.

As the muscles in your face contract, they can put a lot of pressure on the plumbing system that is in charge of making your tears.

That’s what I found out from my friend Karin Biggs, an adjunct professor at Washington State University who teaches anatomy.

She told me that we have two little almond-shaped structures called the tear glands, or the lachrimal glands, that produce our tears. These glands are located up near the eyelids, and it is likely they are making tears at this very moment.

“Tears are made all the time,” Biggs said. “They are responsible for keeping our eyes moist, helping us see and keeping our eyes healthy.”

Meanwhile, there are also two tiny tubes located near the inside corner of your eyes. These tubes, or lachrimal canals, are where the tears can exit your eyes as you yawn.

Like a very slow faucet, the teary fluid is constantly being released from the gland. Gravity pulls the fluid down and around the eye. You might think of it like putting a ball in your bathroom sink then running the water faucet over it. The faucet is your gland, the drain is where tears exit and the ball is the eye.

“When we yawn we are contracting all the muscles in our face,” Biggs said. “We are just squeezing the tears out of the gland and out of the tubes because we have squeezed all of our face at once.”

Biggs also told me there are 43 muscles in the human face. You may squish up a lot of those face muscles when you sneeze or laugh, too.

The muscles in our bodies can help us do all kinds of things. Biggs told me there are even some muscles people have that other people seem to be missing. The plantaris muscle in the knee is one of them. Only about ten percent of people do not have this muscle, but they usually seem to be fine without it.

But tear ducts and tear glands in our eyes are among the many body parts that humans have in common. This plumbing system helps you create, transport and drain all your tears.

The ability to make tears is all a part of the human experience. But other animals like cats and elephants can make tears, too. Tears are mostly water with some other ingredients that help keep our eyes in good shape.

Whether your tears come from crying, sneezing, laughing or yawning, they are often a good sign your body is taking care of you and that your eyes are working well.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Frost Shapes

Dr. Universe: When frost freezes, it makes shapes like flowers and ferns. Why does it look like that? – Grace, 13, in Calgary

Dear Grace,

You’re right: frost can sometimes form patterns that look like the ferns or flowers we find in nature.

Those frosty shapes we see on the surface of windows start out as water in the air, said my friend Kai Carter. Carter is a meteorologist with Washington State University’s AgWeatherNet team.

If you’ve ever had a glass of ice water, you may have noticed droplets formed on the outside of the glass. The droplets actually came from water in the air. This water condensed from the air onto the surface of your cup, which means it turned from a gas to a liquid.

This is similar to what’s happening when dew forms on grass. But frost is a little bit different, Carter said.

When frost forms, conditions have to be just right. As water from the air lands on a really cold surface like a windowpane, the water molecules freeze and join together with other water molecules to form patterns of ice crystals.

An ice crystal is made up of two building blocks: hydrogen and oxygen. These hydrogen and oxygen atoms form a hexagon shape that is a kind of six-sided ring. Even though we may not be able to see them with our eyes, these hexagon shapes can repeat in a pattern across the frosty surface of the window.

Sometimes the water molecules can form into one big sheet of frost. But sometimes things can get in the way of the water molecules. They may have to take a new path as they freeze to the surface of the glass.

If the molecules run into something like a speck of dust, salt or even a bit of washer fluid from a car window, they may change their direction. As you’ve observed, they can start to branch out into shapes that might look to us like feathers or ferns or tree limbs.

In mathematics, we call this kind of thing a fractal design. A fractal pattern repeats itself at different scales. One other place you can also find fractal patterns in ferns. The fern frond looks like it’s made up of little fern fronds which look like they are made up of even smaller fern fronds. Next time you see some frost take time to observe its detailed patterns with a magnifying glass.

Even if you don’t live someplace where it gets really cold, you can actually make your own frost right in the kitchen. All you need is a tin can, salt and ice. Fill the tin with ice and 4 tablespoons of salt and mix it up for a minute. Wait a few minutes and see what forms on the outside of the tin.

The salt is important because it melts the ice, while at the same time helping the mixture drop below freezing. Why do you think that might be? What happens when you add more salt or more ice? Tell us about your frosty experiments sometime at Dr.Universe@wsu.edu.

Dr. Universe

druniverseKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Pond Water

Dr. Universe: Why does water in ponds not get soaked up by the dirt at the bottom? – Rocky, 11, California

Dear Rocky,

That’s a great observation. If we investigated the bottom of a pond, we might find a few different things. Besides a few fishes and frogs swimming around, we might observe mud, algae, rocks and soil at the bottom.

My friend Joan Wu, a hydrologist at Washington State University, is really curious about the water on our planet. She told me a few different earth materials help keep pond water from seeping down into the ground.

Let’s imagine we filled a jar with one of these earth materials: rocks. Inside the jar, we would see some gaps between the rocks. If we poured water into the jar, the water will be able to move into those empty spaces. But now let’s say we had a jar of rocks, and we poured in some sand.

This time, the grains of sand would fill spaces between the rocks. Next, we could add particles of earth called silt that are so small they could fill in any spaces between the grains of sand.

Finally, we could add some even smaller particles of clay. In the jar—or the bottom of a pond— these materials are packed together. The material isn’t very permeable, which means it can keep the liquid from passing through it.

“Over a long, long time, the bottom of the pond itself evolves and changes,” Wu said. “The materials settle and the little particles, or sediments, fill in the large pores.”

As water, wind, gravity and even animals break down rocks, the rocks become smaller and smaller particles that sink to the bottom of the water. When water runs across the Earth’s surface during a storm or as snow melts, these fine materials can also end up in a pond.

For the most part, these materials keep the pond from losing too much water, but sometimes a little does escape into the ground. Meanwhile, a little water can also escape into the air.

“Eventually, you will lose water from the top and from the bottom of a pond,” Wu said.

We lose the water from the top of a pond because of something called evaporation. You may know about evaporation if you’ve ever seen a puddle on a sidewalk that was there one day and gone the next.

When the sun heats up the surface of water, the water can turn from a liquid into teeny tiny drops called vapor. The vapor rises up into the atmosphere where it can eventually become clouds. Those clouds help produce rain and snow that fall back into lakes, rivers and ponds.

When we take the time to look, we can find a lot of connections between our atmosphere, water and earth. These systems shape many habitats for life on our planet.

The next time you visit a pond, see what kinds of living things call it home. Who knows, maybe one day you’ll be a scientist who can help us learn more about the world of water.

Dr. Universe

druniverseKnow a kid with a science question?
With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Tree Sap

Dr. Universe: Why do trees have sap? -Aliyah, 8, Kirkland, WA

Dear Aliyah,

Just as blood moves important stuff around the human body, sugary sap moves important things around a tree.

My friend Nadia Valverdi told me all about it. She’s a researcher at Washington State University who studies how apple and cherry trees survive in different environments.

When we eat food, like a delicious apple or a handful of cherries, we get important nutrients.

Along with some help from the digestive system, our blood helps carry nutrients to different parts of the body to keep us strong.

Trees need nutrients, too. They use their roots to suck up nutrients and water from soil. They also have the ability to make their own food: sugars.

Trees absorb sunlight through their leaves and can use this energy from the sun to make sugars from water, carbon dioxide gas from the air and a few other ingredients.

A lot of sugars are made in the leaves, but they don’t do the tree much good if they just stay in one spot. The sugars have to get to other parts of the tree to help it survive. That’s where the sap comes in.

“Its main task is to make sure that every organ is well-fed and growing,” Valverdi said.

While our blood moves through tube-like veins and arteries, sap flows through two different tube-like parts of the tree.

One part, called xylem, moves important stuff like water and nutrients from the bottom of the tree to the top—from its roots to its leaves.

The other part, called phloem, moves important stuff from the leaves to other parts of the tree, such as the branches, roots and fruit.

I asked Valverdi how a sticky, gooey liquid like sap could move through these tubes. After all, sap doesn’t seem to move on its own.

It turns out that some liquids, such as sap, can move through a narrow space without any help from gravity or other outside forces.

This can happen in plants or trees when sap escapes through tiny, microscopic holes in the leaves. When sap molecules escape the leaf, more sap molecules move in to fill the empty space and keep the sap flowing upwards through the tree.

It’s a phenomenon we find happening everywhere from house plants to big apple trees to celery stalks.

“All trees and plants have sap,” Valverdi said. “The difference is that sometimes in big trees, we can see it with our eyes because it is more gooey.”

One really gooey kind of sap you might have seen before comes from sugar maple trees. You may even put it on your pancakes or waffles. You guessed it, maple syrup is a kind of sap.

Just like us, trees have systems that help them move important stuff around. These systems help the plants survive. When trees do well, that’s good for us, too. They do so many things for us from making the oxygen we all breathe to giving us delicious fruit to eat.

Dr. Universe

You can learn more about the xylem and phloem in this simple activity using food coloring, water and some celery. https://www.youtube.com/watch?v=KIug9Foou3s

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Stained Glass

Dr. Universe: How do people stain glass to make it all the colors it can be? – Emily, 10, Edmonds, WA

Dear Emily,

Ever since humans discovered they could use sand to make glass, they’ve been experimenting with it. They even learned how to control the colors.

My friend Dustin Regul is a stained glass artist and painter who teaches fine arts at Washington State University. He told me more about where glass gets its color.

“It’s actually metals that help change the color of the glass,” he said.

We can add these metals to glass in the form of a compound. A compound is a combination of one or more elements. For example, table salt is a compound made up of the elements sodium and chloride.

Yellow glass can be made using a compound called cadmium sulfide. Red glass can come from adding gold chloride. Manganese dioxide can make glass purple. Blue glass comes from adding the compound cobalt oxide.

Glassmakers add in compounds when they melt the sand. The temperature has to be just right for everything to work. They heat the sand to about 3,000 degrees Fahrenheit—that’s even hotter than lava. As the melted sand cools, it becomes glass.

It turns out, glass made from melted sand doesn’t always instantly become transparent. The glass sometimes has its own natural color.

“You can imagine really old glass bottles,” Regul said. “They kind of have that bluish or greenish tinge.”

Glassmakers also figured out that a compound called sodium nitrate could help clear up the glass.

Regul said glass is a pretty unusual material. It’s not a solid or a liquid. Scientists call it an amorphous solid, which means a state somewhere in the middle of those two states of matter. It’s also a very fragile material.

Regul must be very careful when he works on stained glass projects. Before he gets started, he makes a plan and draws out his design on paper.

Next, he cuts up the paper drawing into pieces. It’s a guide that will help him as he cuts pieces of glass into shapes with a special glass cutting tool. Finally, he uses copper tape to connect the pieces together and applies heat to seal it all up.

In medieval times, when stained glass first became really popular, people used a different technique. The glass pieces were held together with long strips of a bendy material made of lead. On each side of the lead strip was a little channel where the edge of glass could be tucked in. And like the technique Regul uses, adding heat to the strip helped keep the glass in place.

Humans can use these really small pieces of glass—in all sorts of colors—to form a bigger picture or story. Whether you are in the lab or the studio, it’s amazing what you can create and discover when you set your mind to it.

Dr. Universe

P.S. Be sure to check out the Ask Dr. Universe podcast on Spotify, iTunes, or at https://askdruniverse.buzzsprout.com/.


docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Exercise

Dr. Universe: Along with many others, we are at home during the coronavirus pandemic and Layla (5 1/2) has been learning new exercises to stay healthy. Layla would like to ask: WHY and HOW does exercise help our bodies? She would also like to know what the best exercise is for our bodies. 

Dear Layla,

When we exercise, it helps the body and mind in so many different ways.

One important muscle that benefits from exercise is the heart. Maybe you’ve felt your heart beat harder and faster when you run or climb at the playground.

As the heart gets stronger, it also gets better at pumping blood around the body. That’s really important because your blood is full of oxygen you need to help fuel all your body’s systems.

That’s what I found out from my friend Chris Connolly, an associate professor at Washington State University who knows a lot about the science of exercise.

“Exercise is good for the systems inside your body. Your heart, your lungs and your digestive system,” Connolly said. “It’s also really good for your mind.”

When you are active, you are improving your memory, creativity and even critical thinking skills.

Many studies have found that kids who exercise before a test get better scores. Tests can be stressful, but exercising can help reduce all kinds of nervousness. It’s a great way to help us calm down.

>From the heart to the mind, exercise is one way we can care for our bodies. And with so many different kinds of exercises to try, I just had to find out which one was best.

“The best exercise we can do is the one we are going to do consistently the rest of our lives,” Connolly said.

He reminded me humans have different abilities and interests, so how we exercise will look a little different for each person. Find the exercise that’s just right for you and stick with it.

Connolly likes to lift weights and go running. He and his family sometimes build obstacle courses in their yard, too. I don’t know about you, but I think that sounds like a fun way to help stay fit. As for me, I like to explore the outdoors, stretch and climb trees.

Like you, I enjoy trying out new ways of exercising. The question you asked inspired me to try these different exercises that had me hopping like a frog, crawling like a crab, waddling like a duck and stretching out my arms and legs like a starfish. Maybe you can try them, too.

It turns out people need different amounts of exercise as they get older. A lot of kids ages three to five get all the exercise they need just from playing. For kids who are older than five, an hour of physical activity a day can help strengthen bones and build muscle. Meanwhile, adults need about 150 minutes of exercise a week.

It’s important to stay active throughout our entire life, so it’s good to hear you are learning some new exercises. You’re off to a great start. Next time you do your favorite exercises, think about all the wonderful things you are doing for your body and all the things your body does for you.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Down Internet

Dr. Universe: Why does the internet go down? -Mia, 11, Sheridan, Wyoming

Dear Mia,

The internet has helped many people connect with classmates, friends and family during the pandemic. But you’re right, sometimes the connection gets lost.

My friend Dingwen Tao, an assistant professor of computer science at Washington State University, said we can think about the internet like a highway of information.

You may remember from our question about how the internet works that information, like the data that makes up your favorite cat video or science website, travels through electronic signals we cannot see with our eyes.

Tao said these electrical signals can also move through a system of underground wires and cables. The cables and wires run from where you are using the internet to a local internet office to a regional internet office.

One reason the internet might go down is that there is a broken link between these locations. Or these links might get overloaded with information.

“You and your neighbors can share the same link connected to the central office,” Tao said. “It’s like people are sharing the same road, but sometimes if too many people are using the same road, there will be a lot of traffic.”

When there is more information than the links—like those cables or the electrical signals— can handle, then the internet might go down.

Tao said there are few other things that can get in the way of electrical signals.

For example, even a thick wall can block Wi-Fi signals that carry information delivering, say, your favorite podcast. If you are in one room and the router—a device that picks up signals and pushes them to their destination—is in another room, you may lose the signal.

Nature can also play a part in making your internet go down, said Tao. A tree may fall down and knock out some wires during a big storm, or a fire may cause damage to cables.

The disaster could even be hundreds of miles away from you and closer to the regional internet office. But because you are connected to the central office, you and your neighbors might still lose your internet service.

The connections we can make online are important, so many people around the world are helping bring internet to places that don’t have internet access or where the internet is really slow.

Here in Washington, some of my friends at the university are working on a project to help people across the state get access to the internet, including in rural places. The work is helping students get the technology they need to go to school online, so they can keep learning.

As you learn more in school, you may discover more about the innerworkings of the internet. Whenever the internet goes down, there are people who use their deep knowledge of the technology and great problem-solving skills to help us figure out what might be wrong.

They help us get back on the information highway, so we can stay connected—even when we are stuck at home.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Pins and Needles

Dr. Universe: Why do we get pins and needles when we don’t move for a long time? -Jocelyn, 9

Dear Jocelyn,

If you’ve ever had a leg or an arm “fall asleep,” the nerves in your brain and body were sending you an important message.

That’s what I found out from my friend Darrell Jackson, a researcher at Washington State University who studies how drugs affect the nervous system.

The nervous system is made up of bundles of nerve fibers that help humans think, feel and navigate the world. These nerves also help people sense things like temperature, vibrations, pressure and pain.

Jackson said you may feel pins and needles when your nerves get too compressed or squished down. We call this experience paresthesia (pear-ES-theesha).

It takes something called mechanical energy to compress the nerves. This energy might be the pressure from your head resting against your hand during a nap or the pressure on your legs while sitting crisscross applesauce.

When the nerves feel this pressure, they activate a kind of electrical energy. That’s right, you are full of electricity. The body and brain use electrical signals to send information to each other.

The nerves in your tingling leg, arm, foot or hand, can send information along your spinal cord which stretches from the lower back to the brainstem.

“From there, you are relaying the message from the spinal cord to an area of the brain called the diencephalon,” Jackson said.

The message continues on to a section of your brain called the somatosensory cortex. It’s here that you actually become aware, or perceive, that your leg is tingling or that your hand feels like it’s full of sand.

“Once you get up and you start moving around, you’ll get information immediately,” Jackson said.

All of this information moves through the brain and body really fast—about 11,679 feet per second. That’s like running nine laps around a standard running track in a single second.

When the body senses this tingling pain, it activates another pathway in the body. The brainstem helps send information back down to the spinal cord to make the body less painful and less tingly.

If you compress your nerves for too long, it can damage your ability to sense the world. The pins-and-needles feeling can be a useful strategy to protect your nerves and keep you healthy.

Our nerves are really important, and there are more than 7 trillion in the human body. Jackson reminded me our nerves not only help us sense pain but also play a big role in the reason why we have memories.

Jackson said one unsolved mystery about the brain is exactly how humans store their memories. Scientists are still really curious about it. But that’s a question for another time.

The next time you experience paresthesia, maybe you will remember something you learned from investigating this very question. Maybe you will take a moment to remember all the amazing things your body and brain do for you each day.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Apple Cider

Dr. Universe: How do you make cider? -Julianna, 7

Dear Julianna,

We can make cider with juice from apples. There are many different kinds of apples and a few different ways to squeeze out the juice.

My friend Bri Ewing Valliere told me all about it. She’s a food scientist at Washington State University who knows a lot about cider.

The first step is to pick out the apples. Honeycrisp apples will make a sweet cider. Granny Smiths are more acidic and will make a tart cider.

“We could make a single batch of one kind, or we could mix different kinds of apples together and see how it turns out,” she said. “No matter what, it’s going to taste good.”

It’s important to wash the apples to remove any dirt or bacteria. Next, it’s time to squeeze out the juice.

“It’s not like oranges or grapes where you can just squeeze them and the juice comes out,” Valliere said. “We need to get the apples into smaller pieces.”

After a grown-up helps cut the apples into quarters, the slices can go into a juice press. One kind of press is a basket press, which is like a small barrel with a device to grind up apples.

There’s also a wooden plate that goes inside the barrel on top of the ground-up apples. As we push down on the wooden plate, the force squeezes out the juice from the fruit.

The juice flows out the bottom of the press, which works a bit like a pasta strainer. It separates the apple solids from the liquids. As the juice flows from the press, we can catch it in a jug or bucket.

Valliere said another kind of press is called a bladder press, which has a balloon-like device that pushes against the fruit to squeeze out the juice.

While you may not have a basket or bladder press at home, with the help of a grown-up you can find a recipe online that uses similar steps: use small pieces of fruit, press the fruit to make some juice, and pasteurize it.

When we pasteurize the juice, it helps kill any harmful bacteria that could possibly make us sick. All we have to do is heat up the juice up to at least 160 degrees Fahrenheit. Finally, it’s time to enjoy the cider.

While some cider comes from small farms or our kitchens, there are also machines in factories that produce thousands of gallons of juice.

Valliere told me that juice processors sometimes will add something called enzymes to the pressed juice. The enzymes help turn the light brown, cloudy cider-looking juice into the clear, golden liquid we know as apple juice.

A big part of the reason we have apple juice and apple cider is also because of the hardworking farmers and farmworkers who take care of our apple orchards—and we have a lot of orchards here in Washington State.

The next time you take a sip of cider, think of all the people who helped make it and all the science in your cup.

Dr. Universe

Are you curious to learn more about how basket presses work? Check out this video from the Cedar Creek Grist Mill. This historical mill in Woodland, Washington is listed on the National Register of Historic Places.


docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Gummies

Dr. Universe: How are gummies made? -Hayden, 11, Webb City, MO

Dear Hayden,

Gummies can come in all different shapes and flavors. Maybe you’ve had gummy worms, gummy bears, or peach rings.

It turns out that gummies require just a few simple ingredients. That’s what I found out from my friend Connie Remsberg, a pharmacist at Washington State University.

She said making gummies requires a little gelatin, water, a mold, and some help from a grown-up.

If you want to make gummies at home, you can warm up about ½ c. of water on the stove. Add a 3 oz. package of flavored gelatin (which contains sugar). Then add one tablespoon of unflavored gelatin.

Mix it all together until it is dissolved and ready to come off the stovetop. It’s very important to ask a grown up for help and to be super careful when working around hot surfaces. A good scientist—or gummy maker—always puts safety first.

The gelatin is a made up of things called proteins and peptides. They come from animal bones or cartilage. When you dissolve gelatin in water, the tiny proteins act kind of like spaghetti and get all tangled up together. Between the tangles, there is space to hold sugar and water.

Next, you will need something to shape your gummies. A silicone mold is handy because it won’t melt when you pour in the warm mixture. Some stores sell molds with shapes like little bears built right in. Be sure to spray the silicone mold with nonstick cooking spray before filling in the shapes.

If you don’t have a silicone mold, you can spray the bottom of a metal pan and pour the mix into a thin layer. Later, you can use cookie cutters to cut different shapes from the gummy slab. If you have some extra plastic straws laying around, you can follow these instructions to make gummy worms.

After you have your mix in the mold, put it in the fridge until the gummies form. Oh, and if you want to make a vegan version of gummies, you might use agar agar powder, which comes from seaweed and works as an alternative to gelatin.

Remsberg is very curious about compounding—or how pharmacists can combine different ingredients together to create a medication that’s just right for a patient.

She told me that sometimes pharmacists will create gummies that contain a person’s medicine to make it easier to take. Gummy vitamins are just one example. The body needs 13 different vitamins so some people will take a vitamin gummy in addition to eating fruits and vegetables.

One other fun way to experiment with gummy bears—even the kind you buy from the store—is to soak them in different liquids, or solutions, such as water, saltwater, vinegar, or bubbly soda water. Let them sit for a few hours, or overnight, and observe what happens.

Do they shrink? Get bigger? Explode? Okay, spoiler alert, they won’t explode. But tell us what you discover and why you think it all happened at Dr.Universe@wsu.edu.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Spiders In Their Webs

Dear Dr. Universe: Why do garden spiders hang upside down in the middle of their webs? -Abree, 10, New Jersey

Dear Abree,

That’s a great observation. Garden spiders and other orb-weaver spiders crawl all around their webs, but we often see their heads pointing down toward the ground.

My friend Todd Murray, an entomologist at Washington State University, told me about a group of scientists that had a question a lot like the one you’ve asked.

These scientists used mathematical models to learn about orb-weaver spiders and how they move around the web. They discovered spiders that wait with their head down for prey can reach prey faster than spiders that wait with head up for their prey.

While there are exceptions, this position gives spiders an advantage when getting food. Sometimes prey will hit the top of the web, but end up tumbling to the bottom of the web. A spider higher up on the web with its head facing down would be able to see prey below. Gravity also helps spiders as they run down the web.

Murray reminded me how different kinds of spiders can make different webs. Orb weavers tend to make webs in circle shapes. These spiders have parts called spinnerets located in their rear ends, or abdomens, that produce the silk.

Some orb-weavers may create a trap line with their silk, which attaches them to the middle of the web. When an insect hits the web, the trap line vibrates and the spider can sense dinner has arrived. It might just be a fly, mosquito, moth or wasp.

As fall gets underway, orb weavers eat lots of insects and get bigger. You may identify an orb weaver from its brick red to orange body with white splotches. We see quite a few orb weavers in Western Washington at this time of year. You may notice more spiders and webs in your neighborhood, too.

We are still learning exactly why some spiders build certain kinds of webs. Murray said a wasp in Costa Rica has even revealed how a spider’s web designs can get hacked. The wasp glues an egg on the spider’s abdomen. When the egg hatches, the little larva attaches to the abdomen and starts living off the spider.

“That grub sits there and steals the nutrients from the spider like a vampire does, or a tick, or other blood-sucking creature,” Murray said. “As that grub grows on the spider, the spider does a really amazing thing.”

On the last night of its life, the spider start builds a totally new kind of web that looks a bit like a hammock. Once the hammock is made, the spider puts the larvae into the hammock.

“It really does show you how those web-building abilities are hard-wired in the spiders, but that they can be manipulated,” he said.

If you keep asking great questions like scientists do, maybe you’ll help us learn even more about the world of arachnids. In the meantime, keep an eye out for the spiders’ beautiful webs.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Ant Mounds

Dr. Universe: Why do ants build mounds? – Isabelle, 4, Eagan, MN

Dear Isabelle,

Ants build mounds in all shapes and sizes. Beneath those piles of dirt, ants are building their underground homes.

That’s what I found out from my friend Rob Clark, an entomologist who studies bugs on plants. His job is to figure out if bugs make a plant sick or help the plant grow.

He told me ants are one of the most diverse insect families. Scientists know about nearly 13,000 species—and each ant species makes a different kind of nest.

Carpenter ants might make their nests in dead wood. Acorn ants make their nests in small twigs and acorns. Then there are ants that create massive underground mazes that are like cities just for ants.

Ants are pretty good at digging underground tunnels with their little jaw-like mouthparts, too.

“The workers use their mandible to carry the dirt and make space for the queen ant and the larvae,” said Clark. The larvae are their babies who will grow into workers.

Some ants, like harvester ants, will dig nests up to ten feet deep. While some ants make hills with the dirt they dig out, other ants make mounds they’ll actually live inside.

Thatch ants can make mounds that are up to four feet tall. The ants move around a lot of soil and bits of plants to shape their home. They like to build the mounds in a sunny spot, Clark said. Ants don’t like the cold. The babies need a warm environment and so do the workers.

Clark told me he actually saw one of these mounds while he was out in the field and thinking about your question. There were a lot of busy ants crawling around the outside and the inside of it.

It turns out, almost all ant nests start out with a young queen who has never had a colony before.

The queen excavates a small hole in the ground and picks up the soil with her mandibles. She will lay a few eggs and the ants that hatch will become workers.

“As she lays more eggs and more workers grow up, they have to expand the size of their house,” Clark said.

While ants can take care of the house, they can also help with jobs like farming aphids, another little insect.

Aphids have sugary poop, called honey dew, that comes from the sap they eat. Ants eat honey dew and protect the aphids from other predators, like a shepherd tending to a flock of sheep. It’s all part of something called mutualism, which means two living things helping out each other.

Now you know, ants on our planet make different kinds of nests, but they do it for similar reasons. They need to create a safe place for their colony to eat, work, and live. A single colony can contain thousands of ants and they all help each other survive.

Next time you see an ant hill, think about all the ants that made it and that there is a whole little world beneath it.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Robot Language

Dr. Universe: Do robots have their own language? And is there a translator? – Hank, 8, Virginia

Dear Hank,

Robots do have their own language—and yes, there’s a translator.

That’s what I found out from my friend Manoj Karkee, an engineer at Washington State University who is also really curious about robots.

Karkee and his team work on lots of robots that help farmers do important jobs. They can program robots to do different tasks such as pick apples or pull weeds.

Robots are machines that use computer languages to work. But this language is different than the one humans use.

The English language, for example, is made up of more than a hundred thousand words which are made up of just 26 building blocks called letters. Robot languages are built on just two basic building blocks.

“In a very basic form, computers, and for that matter robots, run with ones and zeroes,” Karkee said.

You might think of these ones and zeroes kind of like a light switch. The ones and zeroes help computers know how to send a current of electricity through robots or other electronics.

Zero stands for “off.” One stands for “on.” It’s all part of the binary system. In binary, for example, the number one is “0001” and the number two is “0010” and the number three is “0011.”

The combination of ones and zeroes can also represent letters to form words like “Hi.” The capital letter “H” for example is written as 01001000 in binary. The lowercase letter “I” is written as “01101001.” But there’s a bit of a catch.

“These days when we have to tell robots to do something, we don’t provide ones and zeroes,” Karkee said. “We provide a set of instructions in a language that is not like our human language, but that humans can understand.”

Lots of different computer scientists throughout human history have worked with those ones and zeroes to build more complex robot languages. These are called programming languages. Karkee and his team had to create a specific program, for example, to help the robots pick apples.

Karkee said that creating robot and computer programs requires a lot of math. So, if you want to program or build robots one day it is important to practice those math skills.

But the hard work pays off, especially when you get to build something new and amazing that can help people do important things.  Humans have programmed some robots to speak in human languages. Other people have programmed robots to translate human languages.

“Robots and other computer programs can act as a translator of human language. There are intelligent programs that can translate English into Spanish or Spanish to Nepali,” he said.

Of course, it took the work of programmers to tell the robots how to do that task in the first place.

Who knows, maybe one day you will help us create new languages for robots or come up with ideas to change our world. You might just become a translator yourself—connecting humans to the world of robotics.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Coins

Dr. Universe: How are coins made? -Dahlia, 10, Olympia, WA

Dear Dahlia,

In the United States, pennies, nickels, dimes, quarters, and other coins are made through the U.S. Mint. It turns out, they’ve been making a lot more coins than usual during the global pandemic. But more on that in a moment.

It takes both science and art to make coins. Coins are made from metals that have been mixed together. We call these kind of metals alloys. The very first coins in the world were made thousands of years ago in Turkey from electrum, an alloy of gold and silver. A penny is made from an alloy of copper and zinc.

According to the U.S. Mint, an artist will design the coin with all its details. Then sculptors create a model of the coin in clay or using a digital model and use it to make a plaster cast.

People scan the plaster cast using a computer and the computer’s software helps cut the coin design into the end of a metal cylinder. The metal cylinder is used to create more stamps, or dies, that will be used to press the coin design into metal.

Meanwhile, a machine cuts out flat circle shapes from sheets of metal. The circles are called blanks. The blanks heat up, get a bit soft, cool, go through water, and dry.

They go through a machine that raises the edges of the coin before going through another machine that presses the design into the coin.

Finally, the coins are bagged and shipped out to banks. We use them as we buy different things or do laundry at the laundromat.

Each month the U.S. Mint produces about 1 billion coins, which are made in Philadelphia, Pennsylvania and Denver, Colorado.

But because people are trying to prevent the spread of the novel coronavirus, they haven’t been exchanging many coins lately. There are fewer coins moving through the economy.

That’s what I found out from my friend Elizabeth Reilly Gurocak, an economist at Washington State University. She’d been noticing a lot of signs at restaurants and supermarkets informing customers that the country is having a coin shortage.

Your question even inspired her to start collecting coins from around the house and from family members. She takes the coins to counting kiosks at stores or to the bank to exchange for paper money.

“I’m going to start paying for things with coins just to put them back in the economy,” she said. “I’m going to be like the coin fairy!”

To help add more coins to the economy the U.S. Mint also plans to make about 1.65 billion coins each month for the rest of the year. You can help with the coin shortage, too.

“Empty those piggy banks,” Reilly Gurocak said. “Bring coins to the bank to exchange for paper money, buy things with coins, or take them to coin kiosks. We can solve this problem together.”

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Dogs Telling Time

Dr. Universe: Can dogs tell time? -Sam, 8, Indiana

Dear Sam,

Dogs might not use clocks to tell time like humans do, but they are pretty good at following a schedule. They often know when it is time for a walk, dinner, or sleep.

A lot of animals rely on something called a circadian rhythm, a 24-hour cycle, to help them figure out when it is time to do different things. This system is sort of like an inner clock.

That’s what I found out from my friend Lynne Nelson, a veterinarian and researcher at Washington State University who takes care of lots of animals.

The circadian rhythm system is controlled by light. Humans’ ability to sense light is part of the reason why they are awake and alert during the day. And that’s why when it’s dark out, they go to sleep.

Different animals can have slightly different circadian rhythms. Cats, for example, are diurnal animals. They go out at night and sleep a lot during the day.

In a way, humans have helped dogs learn to tell time. When humans train dogs, dogs learn how to interact with both their humans and their environment.

“Dogs are training their brains based on different events, like owners coming home or when the food is going to come out,” Nelson said.

She also told me about something called entrainment, or the interaction between an animal’s circadian rhythm and the environment. You can think of it sort of like the way your stomach growls to signal that it is almost time for lunch.

“Dogs and cats know when they normally eat. So, they start to get hungry before then and start to bug their owners—even before they put the food out,” Nelson said.

All these things are entrained based on certain genes that control the development of different traits, as well as wiring in our brains, Nelson said.

“It all goes on in our brains and it happens without us even anticipating or knowing,” she adds.

There are some animals that not only have daily schedules, but seasonal schedules. We see this in animals that migrate or hibernate. They get cues from nature in the form of daylight and temperature. As winter approaches, bears know it is time to make their move because days get shorter and the air gets colder.

Nelson is really curious about bears. She said bears are really good at knowing schedules, including when it is the best time to get into people’s trash cans. They use clues from their environment, along with their circadian rhythms, to know when humans will put out the trash. Then they can look for a snack.

“Animals that are food-motivated like dogs and bears can become especially attuned to telling time because of special treats,” Nelson said.

When dogs aren’t eating or playing, they spend a lot of their time sleeping. Dogs sleep for around 14 hours or so a day. No matter the hour, it is almost always prime time for a nap.

Dr. Universe

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Why We Need to Eat and Drink

Dr. Universe: Why do we need to eat and drink? -Victoria, 7, MN

Dear Victoria,

Just like a car needs gas to run, food is the body’s fuel. Food gives us energy, or the power to do work. It helps us run, jump, think, and do all kinds of things.

That’s what I found out from my friend Alice Ma, a dietician at Washington State University.

When you take a bite of food it goes down your throat, or esophagus, and down into your stomach. In the stomach and small intestine, things like bile, acid, and enzymes help digest, or break down your food so your body can absorb the parts it needs.

Food also contains carbohydrates, a substance rich in energy that is made up of carbon, hydrogen, and oxygen.

Carbohydrates can give us a lot of energy, especially when they come from foods like grains, pasta, rice, veggies, breads, legumes, and nuts.

Here’s how it works: the body breaks down carbohydrates into simple sugars, which get absorbed into your blood.

Sugar levels rise and your pancreas—an organ down on the right side of your belly—releases something called insulin, which helps move the sugar into your cells. Your cells can now use the sugar to produce energy, or store the sugar for later use.

There are all kinds of different foods to try in our world. One of Ma’s favorite ingredients is peanut butter. She likes to put it on top of her pancakes, cook it into curry, and dip spring rolls into a peanut butter sauce.

“I cook a lot of different things,” Ma said. “I’m always experimenting.”

She said one question she also gets is, “What would be the one good food to take with you if you were stranded on a deserted island?”

“There’s not one single food that everyone can eat to power everything,” she said. “You need a variety of foods.”

Food also contains lots of different parts such as vitamins and minerals that get absorbed as digestion happens. Protein from foods like meat and peanut butter get stored in muscle, skin, and other tissues and organs. Calcium from things like cheese or green leafy veggies can help the heart pump and keep bones strong.

As a dietician at WSU, Ma helps plan and create meals that fill the bellies and power the brains of thousands of university students. She also encourages people to drink plenty of water.

Water is important to our cells, along with our organs and tissues. In fact, water is what makes up most of our blood. Blood helps carry things like oxygen and nutrients through our body.

We lose a lot of water everyday through things like breathing, sweating, and going to the bathroom. That’s why it is so important to drink water every day.

While food and drinks are important to our health, they are also a big part of culture. Humans celebrate entire days about food and throw festivals to appreciate different cuisines. What kinds of foods do you celebrate in your family? Tell us about it sometime at Dr.Universe@wsu.edu.

Dr. Universe

P.S. If you or someone you know needs access to food or wants to donate to a food bank, search the Food Finder for more information: https://foodfinder.us/

docKnow a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Birds’ Nostrils

Dear Dr. Universe: I am wondering if birds can smell because I have chickens and have seen their nostrils! –Lila, 9, Philadelphia, PA

Dear Lila,

Birds have nostrils, or nares, on their beaks that can help them smell all kinds of things.

That’s what I found out from my friend Dave Oleyar, a scientist with HawkWatch who recently taught a course on ornithology at Washington State University.

He said that when an animal breathes air, they can also breathe in different scents, or combinations of molecules.

The nose has receptors that pick up on scents and send information to the brain, including a part called an olfactory bulb. It’s all part of the olfactory system. You have an olfactory system, too. This system can help animals navigate the world through a sense of smell.

Maybe you’ve used your olfactory system to smell your breakfast, lunch, and dinner.

Birds can also use their olfactory systems to sniff out food. Oleyar told me about a few different birds and their amazing smell abilities.

The kiwi bird uses its long bill to dig into the dirt. Its nostrils are on the outside and very tip of its bill.

“It’s thought that they use that sense of smell to pick up chemicals emitted by their food. Grubs, worms, and other things that are in the ground,” Oleyar said.

Oleyar said one bird of prey that has a really great sense of smell are turkey vultures. He said vultures are scavengers, meaning they eat dead animals.

“They have an incredible sense of smell. They use their nose to pick up chemicals from things that are decaying,” he said.

Turkey vultures have one of the strongest senses of smells among birds. They have been known to smell food that was over a mile away.

But albatrosses, big sea birds that can have wingspans around ten feet, have been known to sniff out food from even greater distances—about 12 miles away.

These big seabirds can pick up chemicals from dead fish or groups of fish. They can even smell the scent that krill give off when they are eaten by fish. That helps them find the fish via the krill.

Birds don’t just have a sense of smell, but many emit different scents of their own. Some birds may use their noses to smell for other birds. This can help them find their family or even start a family of their own, kind of like a game of smell-and-go-seek.

The male crested auklets have little orange feathers on their heads that they use to attract females. But they also give off a citrus scent, along the lines of lemons and tangerines, that the females can use to find them.

While a sense of smell is helpful for birds, it isn’t the only useful or even sometimes the strongest sense—they also use their senses of hearing, sight, and taste. The next time you watch your chickens, or other birds in the neighborhood, maybe you can observe how they use all these senses.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Bees’ Wings

Dr. Universe: What are bees’ wings made of? -Natalia, 13, Kennewick, WA

Dear Natalia,

Bee wings may be small, but they are really strong. I learned all about bee wings from my friend Melanie Kirby, a honey bee researcher at Washington State University.

Kirby said you can think about bee wings as if they were a kite. If you make a kite out of thin tissue, it might rip. But if you make it out of a strong plastic film it will be stronger.

Bee wings are made of a material called chitin (KITE-IN) and it’s a lot like keratin, the material that makes up your fingernails. Chitin is what makes up the wings on each side of the bee’s body.

There are the forewings, which are longer and the hindwings which are shorter. When a bee isn’t flying, the hindwings often get tucked in behind the forewings.

Kirby told me that chitin covers the bee’s entire body and is what makes up the exoskeleton. While you have a skeleton under your skin, bees wear their skeletons on the outside of their bodies.

Bee wings are very thin and transparent, which means you can see through them, a bit like clear glass. But the strength of the material can help a bee carry a lot of nectar. In fact, a bee can carry a load of nectar that is almost equal to its body weight.

I found out chitin isn’t the only thing that makes up bees’ wings. There are also veins filled with hemolymph, or insect blood. And there are air tubes and nerves, too. These parts add strength and stability to the wings, Kirby said.

The veins are kind of like the cross sections of the sticks in a kite. Different types of bees have different vein patterns on their wings.

“Scientists can identify bees by looking at the wings close up under a microscope. And like a kite it has a cross section of sticks, or the veins, which reinforce the wing,” Kirby said.

The wings are connected to muscles in the middle section of the bee, or its thorax. Small barbs called hamuli can connect the forewing and hindwing together. When the hamuli are connected, the wings come together to act like one big kite. This helps the bees glide as they fly.

When the hamuli are separated, the wings are like little rotary motors moving around in a circle like a propeller. This helps the bees get lift and steer themselves in different directions as they fly.

Bees’ wings are the last thing to form before they emerge as adults (bees also develop through metamorphosis similar to butterflies). Their wings will carry the bees through their whole lifetime. Researchers estimate that bees get about 500 miles on their wings before they start to tear and wear out.

During their lifetime, bees will fly from flower to flower. They move tiny grains of pollen around to help plants grow things like nuts, fruits, and vegetables. It’s called pollination. The next time you hear the buzz of a bee’s beating wings remember how important they are to our world and how they help us have food to eat.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Bird Sounds

Dr. Universe: Why do some birds cheep loudly while other birds cheep quietly? -Traver, 4, Indiana

Dear Traver,

That’s a great observation. Birds make all kinds of sounds and for lots of different reasons.

When I got your question, I called up my friend Jessica Tir, a graduate student at Washington State University who studies songbirds.

She said one of the main reasons a bird will make a loud sound is to attract a mate. When the birds find each other, they can make a nest for their eggs and wait for babies to hatch.

Songbirds, such as swallows and starlings, learn their songs when they are babies. Usually, they learn the song from their dad.

“That’s the song they are going to sing for the rest of their life,” Tir said.

One of Tir’s favorite bird sounds is the varied thrush, an orange and black songbird that lives in the Pacific Northwest. They are known for their calls that sound a bit like a UFO. She also told me not all birds have songs. Some birds like hawks and seagulls make noises such as caws, clucks, or screeches.

Birds may also get loud because they want to let other birds know they’ve found some food. It’s almost like an invitation to dinner. Baby birds may also chirp quietly or loudly when they are hungry.

In the lab at WSU, Tir records songbirds’ songs on microphones to learn more about how they communicate with each other, especially when they are hungry. The research will help us learn more about communication and how much food there is some birds’ habitat.

Birds may also get loud when they sense danger in their environment. When birds hear a fellow bird send out a warning, everyone might get really quiet. You might not hear a peep. This can help the birds stay safe from predators.

If birds are being a bit quieter, it might just mean they are sort of chatting throughout the day. Different situations may call for different volumes. This is true among humans, too. Maybe a friend yells across the playground to get your attention or maybe you have to be really quiet and put on your listening ears during story time.

While humans can make sounds with help from their vocal cords, birds use a part called the syrinx (SEE-RINKS). Ostriches have a much bigger syrinx than, say, a tiny swallow, but they work in similar ways.

As air moves through the syrinx, it helps produce the different sounds. It sort of reminds me of how air moves through a musical instrument.

And those bird sounds can make my ears perk right up. Maybe they’ve caught your attention too and inspired you to look for the source of the sound.

The next time you go outside, keep your ears out. How many different kinds of birds can you hear? Can you find the bird making the sound?

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Making Paper

Dr. Universe: Here is my question. How is paper made? I asked this question because there are different kinds of paper and I’m curious about how it is made. Sincerely, Sonakshi, 9, Michigan

Dear Sonakshi,

We can make paper in lots of different ways. It often starts with trees. In fact, one of the first kinds of paper we know about was made in China using rags, plants, and bark from mulberry trees.

These kinds of materials are made up of parts called fibers. Fibers are what help give plants strength to stand up. Humans who eat plants like lettuce or celery have actually eaten some of these fibers. A lot of the clothes we wear come from plant fibers, too.

Plant fibers are called cellulose. Humans aren’t able to digest these fibers because they are really hard to break down. But strong fibers are great for making paper.

My friend Karen Adams, a Washington State University Master Gardener, is really curious about plants. Adams and her family have been missing seeing a lot of friends and family lately. They decided to make paper and write some letters. You can try making your own paper at home, too.

First, you will want to find a bin—something like an empty salad container or a large plastic tub. You will also want to make a deckle. This is a frame with a screen that will help you form the paper. To make a frame, you can glue together popsicle sticks or use an old picture frame.

Where you would normally put a picture, staple or tack on some mesh. This could be the mesh from a window screen or even the mesh from a bag of onions or oranges.

Once you have your bin and deckle, rip up old paper into one-inch pieces. Use about two cups of paper to one cup of water. Soak the pieces of paper in water for 30 minutes or even overnight. Next, get a grown-up to help you blend up this mix to make a paper smoothie (but don’t drink it!).

The goal is to break down the old paper and create a fine pulp. In paper factories, humans sometimes create a soupy pulp of fibers from wood, lignin (which helps hold the fibers together), and a few chemicals. This helps everything break down into a mixture for paper.

After you blend the paper, you can add some small flower petals, tiny seeds, or food coloring. Pour the pulpy mix into the bin filled with about three to four inches of water. Hint: More water will make thinner paper and less water will make thicker paper. You can experiment with this a bit.

Finally, slide the deckle into the water at an angle and lift it up evenly so the surface is horizontal and covered in the pulpy mix. Press the pulp down with a paper towel and then gently remove the towel. Peel off the paper from the mesh and let it dry for a day or so. When it’s ready, you can write a message or draw a picture for a friend.

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Soap Bubbles

Dr. Universe: Why does soap get bubbly? Samuel, 9, East Peoria, IL

Dear Samuel,

When you wash your hands with soap and water, a few different things happen to make bubbles.

Just like you, water and soap are made up of parts called molecules. Water molecules really like to stick together.

If you’ve ever jumped in a puddle or a pool, you may have even observed how water splashes in the shape of little drops. As water sticks together, it likes to form spheres.

That’s what I found out from my friend David Thiessen, a chemical engineer at Washington State University. Thiessen is really curious about bubbles and droplets, especially how they work in different kinds of space technology.

If you took a straw and blew bubbles in a glass of water, you would see air bubbles form underwater. When they rise to the top of the water, they immediately pop. But if you added some soap to the water and blew into the straw, you’d see a lot of foam coming up out of the glass.

That happens because of the nature of the molecules in soap. They are called surfactant molecules and they spread themselves out evenly and sit on the surface of water.

This happens because surfactants have two ends. Thiessen said chemists usually talk about surfactants as having a “head” and a “tail.” The head likes water and wants to stick to the water. The tail doesn’t like water and likes to stay in the air.

When we see a bubble, there is also a force called surface tension at work. This force makes water behave a bit like a thin sheet of rubber. That’s how bugs can sometimes even stand on water without falling through.

The surface tension of water is really high, but when soap is added to water it lowers the tension. The surfactant molecules push their way between water molecules and in the process separate water molecules from one another, reducing their attractive force. The soap helps spread the water out into a thin film that forms a sphere: the bubble.

You can learn more about surface tension with a really simple activity. Pour some water on a plate. Sprinkle some pepper on top of the water. Then put a drop of soap on your finger and touch the middle of the pepper. The soap lowers the surface tension and the pepper scatters to the plate’s edge.

Soap and water molecules can not only help create bubbles but also help cut through grease on dirty dishes and even get rid of germs on your hands. Besides behaving in all kinds of interesting ways, bubbles can also make some really interesting colors.

When light hits the surface of a bubble and reflects off the two sides of the film, the light rays interfere with each other. It creates a phenomenon called iridescence and displays a rainbow of colors.

The next time you wash your hands or help out with the dishes, take a look at how many tiny bubbles you made and remember—it’s chemistry.

Dr. Universe



Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Vaccines

How are vaccines made? – Sibagh, 7, New York City, NY

Dear Sibagh,

It might seem strange, but a small piece of something dangerous can protect you against something much more dangerous. This idea has been around for a long time—and it works.

To learn more, I talked to Guy Palmer at Washington State University. As a scientist who studies infectious disease, Palmer likes learning about how to protect both human and animal health. Vaccines are one way to accomplish this.

Instead of making you sick, vaccines do something very powerful. They help your body learn more about a germ and how to protect you from it.

Vaccines work by pushing a little piece of a virus or bacteria into your body. But they don’t give you the full germ that makes people sick. Instead, they give you a version that’s weak or dead. This germ can’t make copies of itself or spread in your body.

When your body meets the weak germ, it makes antibodies. Antibodies are like little warriors in your blood. They help you fight strong germs if you ever meet them in the future. This gives you a special kind of protection called immunity.

It’s no accident that the word “vaccine” comes from the Latin word “vaca,” meaning “cow.” The first vaccine was invented over 200 years ago, to protect against smallpox. It was created by pulling cowpox from a cow’s skin, then injecting it into a human.

Since then, scientists have invented more complicated ways of making vaccines. They can now safely work with viruses and bacteria in a lab, pulling out and changing pieces of them.

“All vaccines work essentially the same way,” Palmer explained. “The way they’re made is how they differ.”

Some vaccines use only parts of a germ, or a very weak version of it, so it can’t spread inside you. With other vaccines, the germs are killed by heating them up or using chemicals.

Vaccines help you build antibodies like a shield. But in order to make that shield, scientists have to figure out how different germs work. Some germs are more complicated than others, changing all the time. So we don’t have vaccines for everything yet.

“As time has gone on, we’ve gotten more sophisticated,” Palmer said. “We now can find the very piece of the organism that induces the immune response that protects us against disease. But the basic way vaccines work has stayed the same.”

It takes a long time to create a new vaccine. Scientists test them to make sure they are safe, and that can take several months to over a year. “First you have to test it to be sure it doesn’t cause disease in people—that it actually is safe, and there’s not something you weren’t expecting,” Palmer said.

It’s not very fun to get a shot. But remember: the sting is temporary, and the protection lasts. By getting vaccinated, you’re keeping yourself and everyone around you safe.

“We know through research that vaccines are safe,” Palmer said. “They protect us.”

Dr. Universe


Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – Parachutes

How do parachutes work? -Lucas, 11, Alberta, Canada

Dear Lucas,

Have you ever blown on a puffy white dandelion? Your breath sends dozens of seeds scattering, gliding to a soft landing somewhere new.

Look closely at one of those seeds, and you’ll see a familiar shape. The tiny passenger (the seed) has a wispy, circular top, which helps it float to its next destination.

Parachutes work a lot like dandelion seeds—using the same invisible forces all around us. Nicholas Cerruti, a physics professor at Washington State University, helped me learn how.

The air around you is packed with tiny things called molecules. You can’t see them, but you’re constantly bumping into them. This is true for you, and for every object in motion on Earth.

“As an object moves through air, it needs to move the air around it,” Cerruti explained.

Imagine you drop a piece of paper. As the paper falls, it strikes air molecules. Molecules bounce off the paper and each other. Bumping together, they produce a force. As the paper falls, air molecules push against it in the opposite direction. This force slows the paper’s motion.

Scientists call this “air resistance” or “drag.” Gravity pulls everything down on Earth: whether it’s a person jumping from a plane or a paper falling from your hand. But drag works against that pull, slowing it down.

Some objects fall faster than others because they produce less drag. “A classic example is a penny and feather,” Cerruti said. “If you drop a penny and feather at the same time, the feather will drop at a slower rate.”

A feather takes up more space than a penny, just like a person takes up more space with a parachute. With more surface to work against, the air gives a bigger push against gravity’s pull. That’s why someone with a parachute falls more slowly than someone without one.

Parachutes work by creating lots of drag. The same idea appears in nature: in dandelion seeds, bird wings, and more. “Flying squirrels have a skin between their legs that develops like a parachute,” Cerutti said. “Instead of the squirrel dropping out of a tree, they can glide.”

Every year, Cerruti and the Physics and Astronomy Club test these ideas by dropping pumpkins from the top of a tall building.

“Usually we use parachutes on pumpkins as a joke,” he said. “We’ll put a very small parachute on, and it doesn’t slow it down very much. But we’ve been doing an egg drop the past couple of years. Using parachutes really does slow down the egg, and it can land safely.”

You can try this out yourself at home. Ask an adult to help you find a coffee filter or plastic bag and some string.

Try attaching your “parachute” to different small objects: an action figure, pencil, or penny.
When you drop them, do they slow down? Can you help your passenger fall to a soft landing? Try it and see what works!

Happy experimenting,
Dr. Universe

docKnow a kid with a science question?
With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – What Tornadoes are Made Of

What is a tornado made of? – Alice, 6, Ames, Iowa

Dear Alice,

Have you ever felt a warm wind blow by you, followed by a cold gust of air? You can’t see it, but you can sense it on your skin. Invisible to you, winds mix together.

Usually, these winds are harmless. But under the right conditions, they can also be the main ingredients for a tornado.

To learn more, I chatted with Jon Contezac, Craig Oswald, and Joe Zagrodnik, a team of Washington State University scientists who are very curious about the weather.

To make a tornado, they explained, you need two big things: rising air and rotating air.

“When you have the right amount of both, a storm is more likely to produce a tornado,” Zagrodnik said. “That’s no guarantee—you’re just more likely to have a tornado under those conditions.”

A special storm called a “supercell” often has those ingredients. Supercells form as a rotating mass, with air rising quickly within.

Different temperature winds can cause rising and rotation. Warm air rises, but cool air sinks. Warm air trapped near the surface can rise fast if there’s much cooler wind above it. When these winds cross paths from different directions, they may spin skyward.

Rising, rotating air can form a funnel cloud: the first visible sign of a potential tornado. Funnel clouds look like an ice cream cone pulling down from the sky. They’re usually dark gray, made of condensed water like other clouds.

Tornadoes get their color from moisture, plus things picked up along the way. “It’s like a cloud at some point,” Oswald explained. “If it reaches the ground and starts to stir up dirt, it will lift that dirt up into the funnel and turn it dark.”

If a funnel cloud’s rotation touches the ground, it becomes a tornado. But many funnel clouds never do. Their rotation fades, and they disappear without causing damage.

Tornadoes aren’t the only weather patterns to form from twirling wind. Where I live in Washington, I sometimes see dust devils: spirals of swirling dirt. But they’re different from tornadoes.

“Tornadoes’ rotation comes from the cloud and goes down to the surface,” Contezac said. “But dust devils have pockets of intense hot air at the surface, and air spins rapidly around those pockets. They’re generated from the surface upward.”

Not all rotating storms cause tornadoes. But it’s important to know how to stay safe if a tornado happens near you. A watch means the ingredients to produce a tornado exist. A warning means a tornado has actually been created.

During a tornado watch, you should be on the lookout for storms in your area. A tornado warning is when you should go to a safe location, like a basement or bathroom. Talk to grown-ups you live with about where to go.

Although scientists know tornadoes’ general recipe, they still hold a lot of mystery. We’re still trying to learn why some storms make tornadoes and others don’t. Maybe someday you can help uncover the answer.

Dr. Universe

Ask Dr. Universe – How Bees Fly

How can bees fly? – Christopher, Kansas

Dear Christopher,

Bees fly like a blur, with wings too fast to see. Often, you hear them before you see them. They’re small, but their sound is unmistakable. Bees hover with a telltale buzz.

And that buzz offers a big clue. It comes from very fast vibrations—the secret to bees’ flight.

That’s what I learned from Steve Sheppard, an entomologist at Washington State University who studies bees.

Look closely at a bee, and you’ll see their bodies have three major parts: a head, a middle bundle, and a large, striped rear. That middle part is called the thorax, home to all six legs and four wings. It’s also the anchor for the bee’s movement.

Bees’ wings attach to muscles in the thorax. They work sort of like spoons inside a shoebox, Sheppard explained.

“Think of a shoebox with the lid slightly smaller than the box,” Sheppard said. “Then you have the wings—let’s say they’re like wooden spoons sticking out through that gap. So you can imagine that if the lid goes up and down, then the wings go up and down.”

Bees’ wings work similarly. They’re hinged to the thorax. When the bee moves its thorax up and down, its wings move too.

But the wings don’t exactly flap up and down. They actually twist in a special figure-8 pattern. Combining short, choppy rotations with incredible speed, bees’ wings can beat over 200 times each second!

When bees churn their wings like this, they spin the air around them. Twisting wings create a vortex, a sort of small tornado. Rotating the air around them, bees can lift their body up, down, forward, and backward. They can even hover in mid-air.

But there’s another very special thing about bee flight. Like birds, bees direct their wings through signals from their brain. When the brain sends instructions to the flight muscles, the wings move.

For most birds, one brain signal equals one wing flap. “When you think of a bird, it sends an electrical signal to the muscle and it says, ‘Boom, contract,’” Sheppard said. The muscle tightens and relaxes, flapping the wing.

But bees’ wings work differently. They rely on something called resonance frequency: very fast vibrations, started by one initial movement. Their brains don’t send signals for every single rotation. Instead, their wings beat by vibrating.

“They just send a signal every now and then, and that’s enough to keep the muscle bouncing,” Sheppard said.

Using this combination of rotation and vibration, bees can move their wings very fast with each brain signal. That’s what helps them beat their wings at such incredible speed.

Bees aren’t the only insects who use this method. Flies and beetles fly like this, too. Even hummingbirds beat their wings with vibration—a very unusual style for a bird.

The next time you meet a bee, you probably won’t see its wings beating within the blur. But you’ll know there’s a lot going on beneath its buzz.

Dr. Universe

Know a kid with a science question?

With help from my friends at Washington State University, we’re investigating tough and smart questions from curious kids around the world.

Submit a question!

Ask Dr. Universe – The Internet

How does the Internet actually work? I know you can type in most anything and it just pops up and all that, but how? – Eden, age 8, Oregon

Dear Eden,

If you wrote me a physical letter, it would take a few days to reach me. You put the letter in your mailbox. A postal worker picks it up. Then it travels between different post offices on its journey from you to me.

But within seconds of you sending this question over the Internet, it was sitting in my inbox. How can this be?

The whole Internet works like the mail system—but much faster. That’s what I learned from Adam Hahn, an Assistant Professor of Computer Science at Washington State University.

You can think of the Internet as one big network connecting different devices. They’re all able to “talk” to each other because they follow the same rules, called protocols. Computers all have their own address, called an “IP address.” An IP address is a long combination of letters and numbers.

The Internet carries information through electronic signals, invisible to you. But it needs physical things to carry these signals. Special devices called “routers” pick them up and push them to their destination, using wires and cables.

Some computers play a special role as “servers.” Servers are like filing cabinets, keeping all the information of a particular website. They receive your request for information, find the right file, and send it back to you.

When you search for something, your request goes from your IP address to the nearest router. That router bounces it to another router, and so on, until it reaches the server. The server sends information back to your IP address the same way, through the router network.

But what are those electronic signals made of? All the information on the Internet travels in the form of “packets.” Packets are broken-up pieces of a file. They’re written in a language of 1s and 0s, which computers can read. Everything you send or receive is made of packets—whether it’s this question, a Google search, or even a video call with family far away.

“You can think of a packet like an envelope, and your IP address as like a zip code or mailing address,” Hahn explained. If you wrote me a letter, you’d send it in a single envelope. But on the Internet, your message travels as lots of packets.

Imagine writing a letter, cutting it into tiny pieces, and sending them in their own individual envelopes. When the letter arrives, it would have to be taped back together!

But on the Internet, information travels faster sliced into pieces. Packets take different routes to arrive at the same place. When all the packets arrive, your computer puts them all back together like a puzzle. This all happens in under a second.

I’m glad the Internet does this work for us. There’s nothing more exciting to me than reading your curious questions. Thanks to the Internet, I don’t have to wait long to see them.

Dr. Universe

Ask Dr. Universe – Orange Carrots

Why are carrots orange? – Caden, 11, NC

Dear Caden,

When you picture the carrot section at a grocery store in the United States, you probably imagine rows of orange. But carrots can come in a rainbow of other colors: purple, yellow, red, and more.

And the first carrots weren’t orange at all. They were stark white.

That’s what I learned from Tim Waters, a Vegetable Specialist at Washington State University-Extension. He studies how to grow different kinds of vegetables, and helps others learn how to grow them too.

Carrots you eat today are domesticated. Domestication happens when humans tame wild plants or animals for many generations. Over a long period of time, people bred the carrot ancestors for traits such as sweet taste and attractive color.

Domestication helps explain how wolves became dogs, and how teosinte became maize. It’s also how a wild white root became sweet and orange.

“Before carrots were domesticated, they were believed to be white and very bitter and woody,” Waters said. “When people began domesticating them, the first types that were bred and fed upon by humans were purple and yellowish in color.”

Scientists think people first domesticated carrots in Central Asia around 1100 years ago.

Even though the first carrots weren’t as sweet as the ones you eat today, people probably weren’t eating the roots.

“It’s known that carrots were first grown primarily for seed and the uses of leaves,” Waters said. But as more colors emerged, the roots became tastier and became the more valuable part of the carrot.

We don’t know exactly when the first orange carrots appeared. But we have a good idea of why that color stuck around—simply because humans liked it.

“Orange wasn’t a naturally occurring color. It was kind of a genetic flaw, and then it was selected for,” Waters said.

One story says orange carrots became popular in the Netherlands in the 1600s. Orange became the national color, so orange carrots were supposedly associated with the royal family and William of Orange. But orange carrots probably weren’t bred by the Dutch. They just became more popular there.

Over time, orange carrots became the most common variety in some parts of the world. “That’s really why, in Western society, everybody perceives carrots to be orange,” Waters said.

But that orange color isn’t just for looks.

Orange carrots are packed with chemicals called carotenoids—specifically, beta-carotene. Your body turns beta-carotene into vitamin A, which helps you grow and protects you from getting sick.

Beta-carotene isn’t just nutritious. It’s also loaded with orange pigment. That’s why vegetables with lots of beta-carotene—like sweet potatoes, squash, and pumpkins—share the same color.

But what about that rainbow of other carrot colors? They have their own special qualities, too. Purple carrots get their color from loads of anthocyanin, a chemical that is healthy for your heart.

Carrot breeders have even created carrots with multiple colors. You can get the best of both worlds: a carrot that is orange on the inside, purple on the outside!

Dr. Universe

Get the full answer!

Submit a question!

Ask Dr. Universe – Popcorn

How was popcorn discovered? – Jalen, 12, Benson, N.C.

Dear Jalen,

There’s nothing like popcorn in progress: the snapping kernels, the warm buttery smell, and the knowledge that a delicious snack will be ready in minutes. It gives you some good time to think and wonder: how did humans first start doing this?

To find out where popcorn came from, I visited my friend Erin Thornton, an archaeologist at Washington State University. Archaeologists study how humans lived in the past—including the things they ate.

To learn the story of popcorn, we have to trace the history of maize.

Maize is another word for what you think of as corn. Humans grow it all over the world today, but it all started in Mexico.

Long before maize, there was a plant called teosinte (tay-oh seen-tay). If you saw teosinte in person, you probably wouldn’t guess it’s the grandparent of your popcorn. “It doesn’t really look like modern maize at all because it lacks large cobs—instead it looks more like a weedy grass,” Thornton said.

But over time, ancient people selected teosinte plants with softer and larger numbers of kernels. Over many generations, this resulted in the plant we know as maize.

Many scientists think all the first corn was popping corn. It was very important to the people who made it. The Aztecs used popcorn for both decoration and for eating. They also had a word, “totopoca,” for the sound of popcorn popping.

The Maya even tell stories about humans being created from maize. “It speaks volumes about how important this crop was to people who lived at that time,” Thornton said.

Popcorn is easily destroyed, so it can be hard for archaeologists to find it after hundreds or thousands of years. But the oldest popcorn ever found comes from a cave in New Mexico, estimated to be 5,600 years old. (Not quite as fresh as your popcorn, straight out of the microwave.)

We don’t know exactly who first discovered that popcorn can pop. But it’s a process that would have happened when people first started mixing dried kernels and heat.

Popcorn pops through interaction with heat. If you’ve ever looked at popcorn kernels before popping, you know they have a very hard outer shell. The insides are very hard too—until heat touches them.

When heat meets the natural moisture in the kernel, it creates pressurized steam within the shell. This steam softens the kernel’s insides. That heat and pressure increases, until the kernel can’t hold it anymore. And then pop! It explodes.

With that pop, the pressure in the kernel suddenly drops. The steam expands. All that inner goodness puffs out. That’s why popcorn looks like a little cloud.

We don’t know if the first popcorn-makers used flavorings. But when European colonists first learned about popcorn, they enjoyed eating it with milk and sugar like cereal!

Thornton told me white cheddar is her favorite popcorn flavor. Which kind do you like best?

Dr. Universe

Ask Dr. Universe – Green Grass

Dr. Universe: What is inside a blade of grass and why is it green? Green is my favorite color. We really like reading your articles in our newspaper.Luke, 5, Ogden, Utah

Dear Luke,

I’ve been wondering the same thing lately.  Every time I go on walks, I notice new splashes of color. Watching bugs in the grass, I pretend they’re crawling through a jungle. Everything is bright and bursting with green.

When I saw your question, I knew Michael Neff would know the answer. Green is his favorite color, too. (In fact, when we talked over video, he wore a green Hawaiian shirt.) Neff researches plants at Washington State University, and he is especially curious about grasses.

If you chopped a piece of grass and looked at it with your eyes alone, you might not see much. But if you looked at it under a microscope, you’d see tiny structures containing even tinier parts.

All living things—you and grass included—are made of cells. Cells are like little building blocks with different jobs. Every blade of grass is made of millions of them.

Plant cells contain a smaller part called a chloroplast. “Chloroplasts look like fat sausage-shaped balloons,” Neff said.

Chloroplasts have a special job: making food. Grasses can’t search for food like animals can. So instead they make it themselves, taking in sunlight and carbon dioxide.

“Food for a plant is a combination of sunlight and carbon dioxide together,” Neff explained. “And the chloroplast is the factory that turns those two pieces into energy.”

But where does the green color come from? Something else inside the chloroplast is responsible: a special pigment called chlorophyll.

Your eyes see color based on light. Many different colors make up sunlight, and objects either absorb or reflect them. When light gets absorbed, you don’t see its color. But when light reflects off objects, including grass, the color reaches your eyes so that’s what you see. That’s why the sky often looks blue. It’s absorbing all the other colors of light, except blue.

The same thing happens with chlorophyll. “Chlorophyll does a very good job of absorbing all colors of light except for green. When we look at the blade of grass, we’re seeing green light being reflected off the blade of grass,” Neff said.

But maybe you’ve noticed grass isn’t always green. Depending on the time of year and where you live, different grass grows at different speeds. Here in Washington, most grass grows in the cool spring and fall weather.

Spring grass looks especially green because it contains new cells. New cells have tons of chlorophyll, reflecting green light.

In the summer and winter, grass might turn brown or yellow. It’s still alive. It just doesn’t have as much chlorophyll. It isn’t putting as much energy into new growth.

But when spring returns, so do the ingredients for growth—lots of water, light, and carbon dioxide. The grass takes it all in, making new cells full of chlorophyll. The cycle begins again.

Tiny blades sprout. Patches of color creep in. And before you know it, green surrounds you everywhere you look.

Dr. Universe

Get the full answer!

Submit a question!