Dr. Universe

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

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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

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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

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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/.


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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

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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

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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

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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.


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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

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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

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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

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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


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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

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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

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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/

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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


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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


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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


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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


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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



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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


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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

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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

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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

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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

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Ask Dr. Universe – Sinkholes

What is a sinkhole? What causes one? – Kathrine, 12, Calgary, Canada

Dear Kathrine,

Sinkholes can be scary to think about. They don’t happen too often, but when they do, they can take people by surprise. The solid ground disappears, and a hole suddenly appears.

It might seem like sinkholes appear out of nowhere. But they actually need specific conditions to form.

To have a sinkhole, you first must have a cave.

“You can think of a sinkhole as the end of the life cycle of a cave,” Kurtis Wilkie explained. He teaches Geology at Washington State University. He is very interested in how Earth’s features form over long periods of time.

A lot happens underground that we can’t see. Dirt and rock layers lie beneath our feet. Water flows around them, shifting and moving these layers.

With the right type of rock, enough water, and a lot of time, a cave can form.

Wilkie said caves often occur in rock called limestone. Limestone is made mostly of calcium carbonate (the same substance that makes up seashells!).

Limestone isn’t a very strong type of rock. It’s full of tiny cracks. They’re hard to see, but big enough for water to run through. Lots of contact with water can make those gaps get bigger. Over time, the limestone dissolves and breaks apart. This process is called erosion.

As the rock dissolves, empty space gets left behind. Eventually, that space gets bigger and bigger until a cave forms. This happens extremely slowly, much longer than any human’s lifetime.

“We’re talking not just thousands of years, maybe millions of years. It’s not as if you start the process now and then 10 years or 100 years from now you have a cave. It takes a very long time,” Wilkie said.

Most caves remain caves. But if water continues to interact with limestone, it can keep slowly eroding. The cave’s roof can become too weak to hold the heavy ground above it. If the roof collapses, the ground above it falls through. That’s how a sinkhole happens, and part of the cave comes to an end.

A sinkhole is the end of a cave’s life—but not every cave’s life. Most caves don’t ever collapse or turn into sinkholes. A sinkhole only happens if the cave’s roof becomes too thin and unsupported. Humans can cause sinkholes to happen more than they would naturally by pumping water from underground, reducing support for the ground above.

Sinkholes happen more in some places than others. You might hear about sinkholes in Florida, an area with lots of limestone. But here in Washington State, where I live, other types of rock abound. So sinkholes are very rare.

The odds of the ground collapsing beneath you are very small. You’re much more likely to get to visit a cave someday.

And if you do, you can look up at its walls and remember the forces that shaped it. All it takes is a special rock, a lot of water, and plenty of time.

Dr. Universe

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Ask Dr. Universe – The End of the Universe

Where does the universe end? – Oriah, 8, Pullman, Wash.

Dear Oriah,

When you look up at the night sky, it can feel like the universe is a big blanket of stars above you. But unlike a blanket, the universe doesn’t have corners and edges. Far beyond what humans can see, the universe keeps going. As far as humans know, it never stops.

When I saw your question, I went straight to my friend Michael Allen to learn more. He is a Senior Instructor of Physics and Astronomy at Washington State University.

The universe is bigger than the biggest thing you’ve ever seen. It’s bigger than the biggest thing this cat can imagine. It’s so big that even your question has more than one very big answer.

Allen explained that you can think of the universe kind of like a rubber band. If you look at a rubber band’s flat surface, you can see it has no beginning and no end. It keeps going around and around in a loop.

Imagine you drew dots on that rubber band. If you pull on the rubber band, what happens? The rubber band stretches, and the dots move further apart. The universe is like that. The distance between all its galaxies, planets, and stars is stretching all the time, like dots on a rubber band. It never ends, but it’s also constantly expanding.

Scientists don’t think there is a true edge of the universe. But there’s an end to what humans can see of the universe. This is called the edge of the observable universe. It’s the farthest we can see, based on how we get information from light.

Everything you see depends on light bouncing off objects. Light reflects off the things around you and your eye absorbs it. When you look at your hand, you see your hand in that exact moment.

But when you look at a star, you’re actually seeing that star in the past. That’s because the light has to travel a very long time to reach your eyes. The farther away the star, the longer it takes. It takes light from the nearest star, the Sun, eight minutes to get to our eyes. Light from the next nearest star, Proxima Centauri, takes about four years to get to us!

Light moves very fast — about 186,000 miles per second — but the universe is very big. So the farthest edge of the observable universe is the oldest light we can see: about 13.8 billion years in the past.

But that edge is just what we can see from Earth. But that’s just what we can see from Earth. Earth isn’t the center of the universe. It’s just one location. The edge of the observable universe depends on where you are. If we were somewhere else in the universe, we would have a different view.

No matter where you are, you can think of yourself as a time traveler of sorts. When you gaze up at the stars, you’re looking up at the past.

Dr. Universe

Ask Dr. Universe – Liking Different Foods

Why do I like buffalo wings and not broccoli? – Joe, 10, New York City, NY

Dear Joe,

You’re not alone—cats don’t like broccoli much either. As a carnivore, I think a nice, meaty buffalo wing sounds great.

But humans are omnivores, meaning they eat both plants and meat. They’ve developed a taste for all kinds of things growing and living all over the world. So where do individual people’s preferences come from?

To find out, I visited Carolyn Ross, a professor of Food Science at Washington State University. Like you, she is very curious about why people like the foods they like.

You probably got part of your preferences from your human ancestors. Humans tend to seek the taste of fat, sugar, and salt. These ingredients are more scarce in nature, but abundant in foods we cook today. (That’s why it can be hard to stop at just one buffalo wing.)

Your individual experiences shape your tastes in a big way. If you’re familiar with a food and have good memories of it, you’re more likely to keep eating it.

But your genes also have an impact. Genes are like instructions written inside the body, which you get from your parents. They affect all kinds of things about you, including the way some foods taste. That’s why some people think cilantro makes a great addition to tacos, and some think it tastes like soap.

Your genes might even make you a “supertaster”—someone very sensitive to bitter tastes.

Your tongue is covered in little bumps called tastebuds. Tastebuds help you sense the flavor of what you’re eating. Humans’ tastebuds can detect five basic flavors: sweet, bitter, salty, sour, and umami (a savory, meaty taste.)

Supertasters have more tastebuds than most, making them more sensitive to different tastes. About 25% of people in the U.S. and Canada have a supertasting tongue. It’s possible you’re one of them.

Supertasting might seem like a superpower. “But being a supertaster is a gift and a curse because you’re very sensitive,” Ross said. Sweet things taste sweeter, but bitter things taste much more bitter.

Broccoli is one of the foods supertasters tend to dislike. “Supertasters find broccoli to be more bitter than people who are not supertasters and may eat less of it, at least when they’re younger. They also find cheddar or aged cheese to be exceptionally bitter. Their food choices are somewhat based on that,” Ross said.

If you’re a supertaster, you might always find broccoli to be too bitter. Even regular tasters find there are some foods they never love. To this day, Ross doesn’t like raw broccoli.

But your tastes might also change over time. It takes about six tries before your like or dislike for a food becomes a stable preference. So give it a few more tries. Check in with your tastes now and then. You might find a food you once hated eventually becomes enjoyable.

As a cat, though, my taste buds can’t sense sweet things. I’ll never know what you humans like so much about donuts.

Dr. Universe

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Ask Dr. Universe – Viruses

How do viruses form? Since the coronavirus has been all over the news, I’ve been wondering this question for a long time. – Samantha,12, N.C.

Dear Samantha,

Viruses are strange things. They’re not alive like you or me. But they behave somewhat that way—spreading, growing, appearing in new forms. How can this be?

There’s a lot scientists don’t know yet about the new coronavirus. But they do know a lot about how viruses work and make people sick.

To learn more, I talked to Sylvia Omulo, a scientist specializing in infectious diseases at Washington State University.

Your body is made of tiny building blocks called cells. Different cells do different types of work. They all follow instructions written in your body: your genes.

Viruses also have genes, but they don’t have cells like you or me. Instead, they rely on other creatures’ cells to come “alive.”

“A virus is a particle of genetic material that causes an infection by invading a cell,” Omulo explained. “It’s extremely small, smaller than a cell.”

You can think of a virus particle like a letter with bad news, tucked inside an envelope. Layers of protein (the envelope) cover a bundle of genes (the letter), protecting it until it’s ready to be opened and read.

Virus particles spread through the air or on surfaces. They cause infections if they get inside someone’s body. The envelope opens if the virus enters a creature’s cell, called the “host.” The virus uses its genetic instructions to take over the cell.

The virus disrupts the cell’s usual work, Omulo said, using its resources to make copies of itself. Those virus copies invade other cells, repeating the process. The host becomes sick as a result.

Usually, the virus copies itself exactly. But because viruses have genes, they also evolve over time. This means they’re changing, even as they’re making copies of themselves. That’s part of how new virus forms emerge.

Viruses have been around for millions of years, much longer than humans. Some only affect plants or bacteria. Some affect only some animals.

Other viruses spread from animals to humans. Omulo explained this is one way “new” viruses appear. A virus might affect humans, but not the animals carrying it. If it gets the opportunity to jump to humans, it can make them sick.

But remember: a virus isn’t alive on its own. It needs an opportunity to enter a cell. It’s your job to ruin that opportunity.

When you wash your hands with soap, you rub off the virus’s “envelope.” The bad news can’t go anywhere. When you keep distance from others, you close your “mailbox.” Virus particles can’t enter your cells or anyone else’s.

Without a host, a virus can’t do anything. That’s why it’s so important not to give the virus that chance.

Stay safe and stay curious,
Dr. Universe

Ask Dr. Universe – Submarines

How do you make submarines? – Luke, 5, Western Washington

Dear Luke,

The next time you’re in the bathtub, turn a cup upside down on the water. Push down on it as hard as you can. See if you can get it to sink below the water.

It’ll be difficult to do! The air inside the cup makes it lighter than the water. But what happens if you turn the cup on its side, allowing water to rush in? You’ll see it’s easier to push underwater.

Those same basic forces make a submarine work.

That’s what I learned from Ian Richardson, an engineer at Washington State University. He is very curious about how liquids and solids interact. He has even helped NASA work on a submarine to someday go to Titan, one of Saturn’s moons.

Buoyancy describes an object’s ability to float. It’s key to making a submarine. “It’s pretty easy to get something to sink and easy to get something to float,” Richardson said. “To get something to stay in the middle of a liquid is very challenging.”

Ships float because they’re full of air. Air is lighter than the water around them. But submarines dive and rise. They’re able to do this because they control their weight using a combination of water and air.

Ballast tanks are the secret. These special containers sit inside the submarine and control its buoyancy.

“These tanks either let water in or they blow water out with air, and that’s how they control their buoyancy. They dive or surface based on how much water is in their ballast system,” Richardson said.  When air enters, the submarine gets lighter and rises. But when the tanks fill with water, the submarine becomes heavier and sinks.

There are other important parts of a submarine’s design. Special parts create oxygen for passengers to breathe. The inside temperature stays steady to protect sensitive technology inside. And they’re usually made of strong metal, like steel or titanium.

Maybe someday you’ll help design these important features. Until then, you can make your own miniature submarine. All you need is an empty plastic bottle, 4 heavy coins, a flexible straw, and tape.

First, have a grown-up help you make holes in the bottle: three on its side, and one in its cap. Screw the cap on. These holes will allow water and air into your submarine.

Next, tape the coins next to the row of holes in the side. Two should go near the top of the bottle, and two near the bottom. They’ll make the submarine heavier, but keep it balanced.

Now, take your flexible straw and put it in the hole on the bottle’s cap. Make sure the straw is pointed up, so it will stick out of the water.

When you’re ready to test your submarine, set it in water. As water enters, you’ll see the submarine sink. But if you blow into the straw, air gets pushed inside. The submarine rises.

Soon you’ll be ready to explore the far reaches of your bathtub.

Happy experimenting,
Dr. Universe

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Ask Dr. Universe – Seashells

How are seashells formed? And why are they different colors? Can seashells live or die? – Caroline, 9, Crestwood, Ky.

Dear Caroline,

Seashells come in an astounding variety. Some are curved and round, others long and tube-like. Some are smooth, others bumpy. Some are large, others small. Plus, they come in a rainbow of colors: red, green, brown, purple, pink, and more.

All that variety comes from the same source: little animals called mollusks, with a mighty muscle called a mantle.

I found out all about them from my friend Richelle Tanner, a scientist at Washington State University. She is very curious about the ocean and knows a lot about mollusks, a type of animal with a soft, moist body.

There are many kinds of mollusks: both on land and in the sea, with and without shells. If you’ve ever seen a snail or a slug, you’ve met a mollusk in real life.

Unlike humans, cats, and other animals with backbones, mollusks don’t have skeletons inside. Many move through life with just their soft bodies. But some grow shells for protection, as a kind of traveling armor.

That’s where seashells come from, Tanner explained. “A seashell is a protective outer coating secreted by the animal’s mantle, which is one of their muscles,” she said. The mantle forms the soft outer wall of their body.

The mollusk’s mantle builds the shell from the bottom up. It absorbs salt and chemicals from the water around it. When it has enough of the right ingredients, it uses them to form a hard substance called calcium carbonate.

Strong, healthy seashells are made mostly of calcium carbonate. (So are eggshells!) A mollusk produces calcium carbonate from its mantle, laying down layers of it over its lifetime. Together, those layers form the seashell.

You can think of a seashell kind of like your own hair. Your hair grows and is part of you, but it isn’t alive on its own. A living mollusk produces a shell with its body, but the shell itself isn’t alive.

When a mollusk dies, it leaves its shell behind. But even after the life of the mollusk inside has ended, its shell is important. Seashells provide shelter for fish and hermit crabs, nest material for birds, and even nutrients for other animals to build their own shells.

You’re right to notice that seashells can come in many different colors. The way the shell forms helps explain where the color comes from.

“The material for the color comes from the mollusk’s environment—so it’s either taken out of the water or from what they eat,” Tanner said.

For example, seashells from warm waters tend to be more colorful than those from cold areas. This might have to do with their diet. Warm Caribbean waters have more colorful foods than the cold ocean near Maine.

We know seashells’ colors come from their environment. But scientists don’t know yet how the colors get spread around, creating brilliant patterns.

If you keep asking questions and hunting for answers, maybe you could help figure this out.

Dr. Universe

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Ask Dr. Universe – “Bears”

Why are bears called bears when they can be called anything else, not just a bear? – Natallia, 8, Yakima, Wash.

Dear Natallia,

You’ve noticed something very important: there’s no natural reason for the words humans use. Any sound could be used to describe a big mammal that eats berries and salmon.

But people who speak English choose “bear.” People who speak Spanish use “oso.” People who speak Maricopa say “maxwet.” They’re all different, but they’re all correct.

That’s what I learned from my friend Lynn Gordon, a linguist at Washington State University.

“Why do we call bears ‘bears’?” she said. “Because we’ve agreed to.”

Humans have a unique knack for speech. They talk about things in the past or future. They make up new words. They even say things they’ve never said before (like you did with your excellent question).

To be understood, speakers of a language agree about its rules. This happens very early, when a baby is first learning to talk. When you were little, you learned by listening to others. You agreed to your language’s rules without even thinking about it.

“Most of what we know about culture people didn’t teach us,” Gordon said. “They acted it out in front of us and we absorb it by being human. We’re driven to absorb the culture and language around us. Our brains are built that way.”

That’s how English speakers have passed down the word “bear” for generations. We don’t know exactly how or when the first word for bears was created. But linguists can hunt for a word’s history by looking at its relatives.

English, German, and Dutch are like cousins. English speakers say “bear,” Dutch speakers say “beer,” and Germans say “bär.” These languages sound similar because they share an ancestor – Proto-Germanic, an old language that isn’t spoken anymore.

Before “bear,” Old English speakers used “bera.” This word may come from the Proto-Germanic “*berô,” meaning “the brown one.” Others think “*berô” might be related to the Latin “ferus,” making it mean “the wild one.” We don’t have any written examples, so linguists use an asterisk (*) to show it’s their best guess.

Others look farther back at Proto-Indo-European, Proto-Germanic’s ancestor. This language had a different word for bears: “*rtko.” That’s where the Ancient Greek “arktos” and Latin “ursus” come from.

But how could “*rtko” become “*berô”? It’s possible people didn’t want to say a bear’s true name out loud, so they said “the brown one” or “the wild one.” People might have been afraid of warning bears they hunted, or calling bears to attack them.

That part of the history involves a lot of guessing. But it’s clear “*berô” became “bera,” and “bera” became “bear.”

All of this shows languages change over time. It’s normal for words to shift in sound and meaning. It’s even normal to create new words. Humans move around, meet new humans, and borrow words as they go. They agree to the rules, but the rules can change.

So whether you call me “cat” in English, “gato” in Italian, or “kedi” in Turkish, it’s all right by me.

Dr. Universe

Ask Dr. Universe – Fingerprints

Dr. Universe: Why do people have different fingerprints? – Mary, 12, South Carolina

Dear Mary,

Did you know even identical twins have different fingerprints? It can be hard to tell twins apart, but a close look at their fingertips can reveal who’s who. The reason lies partly in their genes, but mostly from the unique way everyone’s skin grows before birth.

That’s what I learned from my friend David M. Conley, a professor at Washington State University’s Elson S. Floyd College of Medicine.

“The reason fingerprints are unique is the same reason individual humans are unique,” Conley said. “Variation is the norm, not the exception.”

There’s no single cause for your unique fingerprint design. Instead, it’s the result of both your genes and your environment. This is called multifactorial inheritance.

Look closely at the lines on your fingertips. These are called “friction ridges.” It’s hard to see, but they actually stick up above the rest of the skin.

“Fingerprints are impressions left behind when your fingers touch a glass, or when you put ink on your fingers and press them on a piece of paper,” Conley said. “Friction ridges are the actual patterns on your fingertips and palms.”

Friction ridges grow in different designs, like arches or whorls. If your parents’ fingers have a certain pattern, you might be likely to have it too. That’s because genes give the basic design, and you get your genes from your parents.

Genes are like instructions written inside the body. They give directions things like eye color, nose shape, and more. (Or, if you’re a cat like me, the length of your fur or the number of toes you have.)

Genes also tell the skin how and when to grow. Before a baby is born, they grow as a fetus inside their mother’s womb. The dermis (the inside skin layer) and epidermis (the outside skin layer) grow together. Friction ridges appear where these layers meet, guided by genes.

But these layers don’t grow at the same speed for every fetus. If one layer of cells grows faster, it can stretch and pull the others. As the fetus moves, their fingers can rub against the side of the womb.

These tiny forces push the skin as it grows. Together, they mold the direction of the growing ridges. The result is a unique fingerprint unlike anyone else’s.

Everyone’s skin grows in a slightly different environment. That’s why it’s so unlikely anyone has the same fingerprints as you – about a 1 in 64 billion chance.

Koalas and chimpanzees have unique fingerprints, too. Like humans, their hands and feet are covered in friction ridges. They also spend a lot of time climbing trees, just like humans’ primate ancestors did millions of years ago. That might mean friction ridges give texture to grab rough or slippery things.

Scientists don’t know yet if cats have different pawprints. But have you ever looked at the bumps on a cat’s nose? Some scientists think cats might have unique noseprints. I’m going to go check that out in the mirror later.

Dr. Universe

Ask Dr. Universe – Sea Turtles

Why won’t a female sea turtle lay her eggs in the ocean? How do baby turtles know where the ocean is when they hatch from their eggs? – Jasmine and Shereen, 8, Gainesville, Fla.

Dear Jasmine and Shereen,

Sea turtles spend almost their entire lives in the ocean. Even as babies, sea turtles’ bodies have special traits for living at sea, helping them glide and paddle through the water. After emerging from their eggs, baby sea turtles (called “hatchlings”) scramble to the ocean to live the rest of their lives. Only female sea turtles return to land as adults, to lay eggs and begin the cycle again.

I talked with my friend Frank Paladino to learn more about sea turtles. He completed his Ph.D. at Washington State University. Today he is a professor at Purdue University-Fort Wayne and former president of the International Sea Turtle Society. He is especially interested in leatherbacks, the largest living turtle.

I learned that a female sea turtle must return to the beach to lay eggs, even though she is most comfortable in the ocean. This is because her eggs can only survive on land.

Baby sea turtles breathe through their eggs before hatching. Oxygen passes through the eggshell and membrane, a thin barrier surrounding the turtle. Even buried in sand, the turtle can still breathe through the egg. But they cannot breathe if the egg is in the water.

Sea turtle eggs also need warm temperatures to grow properly. Beaches provide the right conditions to help eggs develop. Mother sea turtles bury their group of eggs (called a “clutch”) in sandy nests to protect them until they are ready to hatch.

But when lots of humans are around, a beach can be a difficult place to lay eggs. “Normally, female turtles do not lay their eggs in the water. But if disturbed when on the beach and distracted multiple nights from returning to the nest, they will dump their clutch in the ocean,” Paladino said.

Humans can also cause problems for hatchlings as they leave the nest and head toward the ocean.

To find the ocean, hatchlings follow the brightest light source. Have you ever noticed how a pond or lake sparkles in the sun? This is because light bounces off the surface of the water. Under natural conditions, the ocean is brighter than the beach because it reflects light from the sun and the moon.

But when humans are around, other light sources can confuse turtle hatchlings. “Lights from houses and hotels on turtle beaches distract them. Instead of going to the sea, they will head toward the house lights which are the brightest horizon,” Paladino said.

Light pollution can be dangerous for hatchlings, so some places have created rules to protect them. Paladino told me that turtle nesting beaches in Florida have shields to block human sources of light. There are even special street lights designed not to confuse hatchlings looking for the ocean.

Sea turtles follow their instincts, in a cycle that takes them from the land to the ocean. Although humans pose challenges to sea turtles, science can help them live alongside each other.

Dr. Universe

Ask Dr. Universe – Why the Wind Blows

Dr. Universe: Why does the wind blow? – Odin, 7, Mt. Vernon, Wash.

Dear Odin,

When the wind blows, it can do all kinds of things. It can help pick up tiny seeds and carry them away, so plants and flowers can grow in new places. It can push a big sailboat across an ocean. We can even harness the wind to make clean energy to power our homes and schools.

That’s what I found out from my friend Gordon Taub, an engineer at Washington State University. He is very curious about wind energy and told me more about why the wind blows.

Whether it’s a breeze, a gust, or a gale, winds are blowing in our atmosphere all the time. When the sun heats the earth, it doesn’t actually heat the earth evenly.

Part of the reason the Earth doesn’t heat up evenly is that the sun is really far away. Because the Earth is a big sphere, when the sun’s rays finally get to us, they are going mainly in one direction. They are mainly pointed at the Earth’s equator. That means that rays have to travel further to get to the ground at the poles than they do at the equator. As the sun’s rays pass through the air, they get weaker.

When the air at the equator warms up, it expands, Gordon reminded me. Things start cycling around as warm air moves in to places where there is cooler air. It is this mixing and movement of air at different temperatures and pressures that gives us our winds.

The wind holds a lot of energy, too. Wind turbines can help take the kinetic or motion energy of wind and turn it into electrical energy that can power our world.

Taub’s students are actually working on a wind turbine project of their own this year and will debut it at a national competition in 2020. If you are curious about wind, maybe one day you’ll join students at WSU to investigate wind power, too.

Maybe you’ve also seen some wind turbines if you’ve traveled across our state. Taub said wind turbines usually start spinning when the wind is blowing about 11 m.p.h. They usually shut down when winds reach speeds of about 44 m.p.h., so the blades don’t get busted up.

You know, we have some pretty strong winds on planet Earth, but that’s nothing compared to other planets. Jupiter’s red spot has winds of up to 250 mph, almost twice the speed of the fastest wind on Earth [163 mph was the highest recorded]. And Neptune’s winds are the fastest in the solar system reaching 1,600 mph—even faster than a fighter jet.

On earth, wind can also help us stay cool on hot days. I think I’m going to make my very own wind-powered pinwheel this summer. You can try to make one of your own, too. We’ll need some scissors, paper, a wooden stick, and a brass fastener. Find all the instructions here and then watch your creation spin in the wind.

Dr. Universe

Ask Dr. Universe – Why Brains are Mushy

Dr. Universe: Why are brains mushy? – First Graders, Waller Road Elementary, Puyallup, Wash.

Dear First Graders,

You’re right, brains are quite mushy. It turns out the three-pound organ between your ears is mostly made up of water and fat.

I found out all about brains from my friend Jim Peters, a neuroscientist at Washington State University.

“It’s gooey. It really is squishy,” he said. “When it is warm, it is kind of like butter.”

The brain may be soft but it is surrounded by a tough layer called the dura materto help protect it. I also found out the brain actually floats around in a kind of liquid. This liquid helps keep the brain from touching the bone of your skull.

The bones in your body are actually made up mostly of minerals, like calcium, which give them strength and hardness. If you bonk your head on something, the bone in your skull is a great material to help protect your squishy brain.

Still, bone can sometimes crack or break. That’s why it is so important to wear a helmet when you are being an adventurous rock climber, bicyclist, or playing football. It protects both your tough skull and squishy brain.

Part of the reason it is so important for brains to be soft is because they need some flexibility to work. The brain can change itself—the actual connections and the way it functions—and helps us make different thoughts and memories throughout our lives.

The brain is actually made of lots of tiny parts called neurons. When you were born, you had many more of these neurons than you do today. As you grow and learn your brain trims these neurons to make just the right connections and circuits.

These neurons that make up the brain communicate with each other to help your body do lots of different things—move, smell, see, touch, and sense the world around you. There are billions and billions of them.

Peters told me these cells are surrounded in a coat of fat called the membrane. The membrane is like a wall that surrounds the cell and gives it a good structure. That way all the parts inside the cell can stay together.

When cells communicate, they use electricity to make it happen. That’s right— your brain is full of electricity. The fatty membrane helps direct the flow of electricity to the right spot so that it can release chemicals called neurotransmitters. So in a way, the squishiness helps brain cells make connections and pass those messages to other brain cells.

The brain is not only soft, but it has kind of bumpy, grooved, or wrinkly surface. If you were to unfold the brain, it would take up quite a bit of space. Some people have estimated it would cover an area the size of one to two pages of a newspaper. That’s a lot of brain tucked into your skull.

Our mushy brains do all kinds of things for us, including helping you read this very sentence and ask big questions about our world.

Dr. Universe

Ask Dr. Universe – When Trees Make Oxygen

Dr. Universe: Do trees still create oxygen and clean the air after their leaves fall off? – Nova, 8, Palouse, Wash.

Dear Nova,

The trees that lose their leaves in fall, such as chestnuts, oaks, aspens, and maples, are called deciduous trees. Once they lose their leaves, most aren’t able to take in carbon dioxide gas from the air or produce any oxygen.

That’s what I found out from my friend Kevin Zobrist, a professor of forestry at Washington State University.

“Don’t fret, though,” Zobrist said. “For they more than make up for it in the summer.”

Leaves play a big part in how trees take in carbon dioxide gas from the air and create the oxygen gas that we all breathe. These gases come in and out of a tree through tiny pores on its leaves called stomata.

These gases are part of a process called photosynthesis. Trees take in carbon dioxide from the air, use sunlight as energy to turn that carbon dioxide into sugars, and then use those sugars as their food. In this process, trees also make oxygen.

Photosynthesis actually occurs in the green parts of the leaf called chloroplasts. These chloroplasts are what give leaves their color.

But as leaves start to lose their green colors in fall and winter, they can no longer do photosynthesis. However, there are some deciduous trees, such as aspens, that have green stems.

Zobrist told me some of these stems can actually do photosynthesis, as well. If the temperatures are warm enough in winter, the stems start to photosynthesize.

But in this case, the tree doesn’t take carbon dioxide from the air. Instead, it uses some carbon dioxide that it makes on its own.

In addition to photosynthesis, trees also go through a process called respiration. The tree will use some of the sugars it makes from photosynthesis to carry out different jobs in their daily lives.

As the sugar molecules break apart, they release energy. This process requires trees to take in oxygen and release carbon dioxide. If you’re thinking that sounds just like the opposite of photosynthesis, you are right. This process happens in both the leaves and the stems.

Trees with green stems may use some of this tree-made carbon dioxide to do photosynthesis after their leaves fall off. Still, there’s not nearly as much photosynthesis going on in winter as there is in summer.

Trees do most of the work creating oxygen and cleaning the air of gases like carbon dioxide in the spring and summer. For the most part, they take a kind of fall and winter vacation.

Still, at any given moment there is a tree on our planet creating the oxygen that we breathe. After all, even though it might be winter where you live, that means it is summer elsewhere on the planet.

While the branches in your neighborhood might be bare, in other parts of the world people are starting to see trees growing their new leaves.

Dr. Universe