Dr. Universe

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

Ask Dr. Universe – Baby Communication

Dr. Universe: Do babies have ways of communicating? –Jalen, 12, North Carolina

Dear Jalen,

Babies can communicate in a few different ways. For the most part, they use their emotions.

Humans come into the world crying, but that’s actually a good thing. In a way, babies start communicating from the moment they are born. Of course, it can be hard for their caregivers to know exactly what they mean with all those cries.

It takes some time, but caregivers can learn to pick up on what different cries are signaling. For example, a baby might be hungry, need a diaper change, or just be uncomfortable.

After babies are born, many will be given a test to see how they react to things in their environment. A baby might even get a gentle pinch or have some boogers softly sucked out their nose to see how they respond.

The person giving the test, usually a doctor, will look to see if the baby pulls away, sneezes, coughs, or twists their face into an expression we call a grimace.

Still, a cry or grimace doesn’t always mean there is a problem. Sometimes babies will cry because they are having a hard time settling down, but if left alone, will figure out how to soothe themselves, which is a good skill. They might suck on their thumbs or distract themselves.

I learned a lot about how babies use emotion to communicate from my friend Masha Gartstein, a professor of psychology at Washington State University.

She told me that crying is just one way babies communicate. After two or three months, babies will usually start to smile with a purpose.

“It’s an amazing thing,” Gartstein said. “That becomes another way of communicating.”

It’s also a nice relief for caregivers, or a baby’s brothers and sisters, especially after hearing lots of crying for a few months. Babies and caregivers can now both communicate joy or happiness.

At about six months old, babies can usually respond to their own names. But they still can’t talk like kids and grown-ups.

Instead, they might use gestures or point at things to communicate ideas to others. They might use their hands, fingers, or bodies to send out a message like, “I want that toy!” or “Look what I did!”

When a baby is about twelve months old, they will start to put together sounds that make up words like “mama” or “dada.” All the while, the baby’s personality is developing, too.

Gartstein also told me about something she studies called temperament. It’s a combination of the emotions and behaviors we each display that are reactions to our experiences or attempts to regulate these reactions.

Perhaps, you are a very calm person or maybe you get easily stressed and angry. These kinds of temperaments often begin when we are babies.

In Gartstein’s lab, she sees lots of different expressions and emotions on the faces of babies who come to visit with their families. The babies even wear little swim cap-like hats with little electrodes that help the researchers learn about their brain activity.

Babies don’t just have the ability to communicate, but sometimes they can help us do science and learn about human nature.

Dr. Universe

Ask Dr. Universe – Axolotls

Dr. Universe: What do Axolotl eat? What species are they? Do you think they are cute? – Erin, 10, Florida

Dear Erin,

An axolotl (ax-a-lot-l) is a creature with big frilly gills like a lion’s mane, tiny eyes with no eyelids, and a mouth in the shape of a smile. They come in lots of colors: pink, black, golden, or grey.

These animals have been nicknamed “the walking fish,” but they are not really fish. An axolotl is a type of salamander.

That’s what I found out from my friend Ed Zalisko. Zalisko earned his Ph.D. at Washington State University and is now a biology professor at Blackburn College in Illinois.

A salamander is a type of amphibian, a cold-blooded animal that has gills, can breathe air, and lives under water. We find axolotls mainly in Lake Xochimilco and Lake Chalco in Mexico. The species name is Ambystoma mexicanum.

Because humans need water to survive, that means there is less water left for some of the amphibians. Axolotls are actually a critically endangered species, Zalisko said.

There are many species of salamander that are part of the group Ambystoma. About a decade ago, Zalisko discovered a new kind of axolotl. These particular axolotls can hold their breath for a whole year!

Axolotls breathe through their gills and lungs and sort of inflate like a balloon. The kind that Zalisko discovered don’t let the air out.

“No one knows why they hold their breath so long,” he said about the BC Axolotl, named after Blackburn College.

When they puff up, they flip over on their bellies. That means when they eat, they eat upside down.

Upside down or right side up, axolotls actually eat all kinds of different things, Zalisko said. They are carnivorous which means they eat meat. Some axolotls like to snack on snails, worms, insects, fish, and sometimes even other kinds of salamanders.

Finally, we explored your third question about axolotl cuteness.

“I think they are spectacularly cute,” Zalisko said. “And you can quote me on that. They just sit around most the time and look as cute as can be.”

In the lab, researchers can watch these amphibians develop in real-time because the axolotl eggs are see-through. It’s kind of like looking through a window.

In addition to being cute, axolotls may be able to teach us a thing or two about how to re-grow limbs, like arms and legs. If an axolotl loses a leg, it can regenerate it. Who knows, maybe one day you can help us learn more about these creatures.

Dr. Universe

Zalisko gives a special thanks to his teachers John H. Larsen Junior at Washington State University and Ron Brandon at Southern Illinois University who studied salamanders for many years.

Ask Dr. Universe – Evergreen Trees

Dr. Universe: Why are evergreen trees green all year? – Emily, 10, Silverdale, Wash.

Dear Emily,

Whenever I go for a hike in the woods, I can’t help but admire the tall evergreen trees. No matter what time of year it is, the pines, hemlocks, cedars, and spruces are usually all green.

My friend Bert Cregg is also very curious about the lives of trees. He graduated from Washington State University and is a professor at Michigan State University.

Cregg told me that evergreens have lots of needles, which are their leaves. We have even seen some trees, such as bristlecone pines, that have had the same needles for more than 16 years.

Each tiny needle on a great big evergreen is working hard to make food for the tree. It all happens through a process called photosynthesis. Here’s how it works:

The tree’s needles contain something called chlorophyll that gives them their green color. But the chlorophyll also has another important job. The chlorophyll absorbs sunlight which the tree can use to turn carbon dioxide from the air and water into sugars. It is these sugars that help the tree grow and stay green.

But while some trees, such as maples, stop doing photosynthesis in the colder months, evergreens keep on photosynthesizing (pho-toe-synth-uh-size-ing). In addition to sugars, evergreen trees also need something called mineral nutrients to help them grow.

In fact, humans also need mineral nutrients, such as calcium, potassium, and iron to help them grow. But while humans get their nutrients from food, trees get a lot of their own kinds of nutrients from the soil.

Cregg said that evergreens are really good at living in cold places where there aren’t a lot of nutrients in the soil.

“Once you have worked hard to take up those nutrients,” Cregg said, “you want to hang on them.”

Evergreens store up all those nutrients and can use them through the winter months. These types of trees are also good at storing up water in their needles which can help them stay green, too.

The nutrients help trees to do all kinds of things, including go through photosynthesis. But I also found out that some even evergreens do lose at least some of their green color. We might see some of their needles at the bottom of the tree start to turn orange. That means those needles are at the end of their lifespan.

“They drop their needles but they don’t do it all at one time,” Cregg said.

We have quite a lot of evergreen trees in Washington state, as you can tell from the state’s nickname “The Evergreen State.” The next time you look up to an evergreen, think about how each little needle is doing the job of keeping the tree green and growing. What kinds of evergreen tree species are growing in your state or neighborhood? Can you find some of their needles or pinecones Or do you have other kinds of trees in your part of the world? Tell us about what you see some time at Dr.Universe@wsu.edu.

Dr. Universe

Ask Dr. Universe – Snow Globes

Dr. Universe: How do you make a snow globe? – Alexa, 10, Salem, MO

Dear Alexa,

If you have a long winter break ahead and are looking for a great way to spend the afternoon, you might just want to make your very own snow globe. There are a few different ways to build a snow globe, but the first thing you’ll need is the perfect container.

To make a small snow globe, you might use something like an empty baby food jar. Or maybe if you want to make a bigger snow globe, you could choose an empty spaghetti sauce jar.

An empty water bottle could also work well for a snow globe. This is a great project to do if you have a few old items you want to make into something new. Once you have your perfect container, you’ll want to fill it up with certain kinds of liquids.

My friend Lindsay Lightner, a Ph.D. student at Washington State University, teaches people how to become science teachers and knows lots of great science activities to try. Her students make lava lamps to learn about something called viscosity. A lava lamp actually isn’t too different from a snow globe when it comes to viscosity.

Viscosity is a property, or characteristic, of liquids. We often use the word viscosity to describe how fast or slow a liquid flows. If you stuck a spoon into a jar of peanut butter, it would probably stick to the spoon. It’s really thick and has a high viscosity—it behaves almost like a solid.

But if we heated some peanut butter in the microwave, it would move around much more freely and have a much thinner consistency. It now has a much lower viscosity. For your snow globe, you will want to figure out how viscous to make your liquid. You can try it out with an experiment.

You can fill up one jar with water. Then fill another jar with water and a teaspoon of something called glycerin. Glycerin is what we sometimes use to make bubbles and it can make water more viscous. It’s easy to find in many stores. You might even make a third jar with a tablespoon of glycerin. You can adjust the amount, as needed.

Finally, you can add your “snow.” There are all kinds of different things you can use for snow. You might make your snow out of aluminum foil. You can use a hole punch to create some tiny flakes that will reflect the light.

If you want to re-use a material, Lightner said you can also use eggshells to make your snow. You could wash out the eggshells and then crush them up with a rolling pin into snowflake-sized pieces. No matter what solid object you decide to use, you will want to make sure it doesn’t dissolve in liquid. Lightner adds that you could also add little toys, like old Lego people, to decorate the inside of your snow globe.

Finally, you’ll want to put the lids on your containers tightly and give them a shake. Which of your snow globes has snow that falls the slowest or fastest? Tell us about what you created sometime at Dr.Universe@wsu.edu.

Dr. Universe

Ask Dr. Universe – Why Microwaves Hum

Dr. Universe: Why do microwaves hum? – T.J., Middle School, Ohio

Dear T.J.,

Long before humans invented microwave ovens, they had to rely on stoves or an open flame to heat up their food.

These days, we can warm up food in a matter of minutes, or even seconds. A lot of parts had to be invented to make that all happen. These parts help electricity flow through the microwave in lots of different ways.

One part called a transformer helps move the electricity from one area to another. As it does so, it may vibrate or shake a little, and that tiny movement can cause a humming noise.

Electricity is actually a big part of what powers microwaves, just as it does refrigerators, lightbulbs, and cellphones. The electrical current travels through a wire, sort of like water through a hose.

Inside of a microwave, we also find tiny parts called diodes which work like gates, allowing electricity to move in one direction but not the other. We might also find some capacitors in the microwave which work to store electrical energy.

You may also be interested to know that microwaves are actually a form of electromagnetic energy.

I found out all about it from my friend Sumeyye Inanoglu, a graduate student researcher at Washington State University. She is very curious about how we can preserve food and use microwave technology to make better ready-to-eat meals.

These kinds of energy move in waves, not too unlike the shape of the wave you see crashing onto the beach.

The light you see with your eyes is also a kind of energy. There are a lot of different kinds of electromagnetic energy, so many that we call them part of the electromagnetic spectrum.

The spectrum is sort of like a rainbow of energy, with the different lengths of waves forming the colors of the rainbow. We find very long waves, like radio waves, at one end of the spectrum, and very short waves, like X-rays, at the other end. Microwaves are in the middle.

Sumeyye told me that many years ago there was a scientist named Percy Spencer who was studying radar and was experimenting with microwaves—the wave, not the appliance.

One day Spencer had chocolate in his pocket and those microwaves ended up melting all the chocolate. That melted chocolate eventually led to the invention of the actual appliance.

The waves are produced inside the appliance from a part called a magnetron. The magnetron is mainly made up of two big magnets. You may also hear some sounds or vibrations coming from a fan that cools the magnetron.

Lots of tiny parts can add up to do really useful stuff. But they’ll also make some noise as they vibrate. Those vibrations are also why moving parts eventually wear out and have to be replaced.

You might just say you are hearing the sounds of engineering. It’s something to think about the next time you are waiting for the microwave timer to beep.

Dr. Universe

Ask Dr. Universe – Naming Places

Dear Dr. Universe: How do people name continents or places on earth? Thank you. – Lila Grace, 8, Virginia

Dear Lila Grace,

Our world is full of so many different places. They get their names in lots of different ways.

One way a place might get a name is from the person who explored it. The Americas are named after an Italian explorer, Amerigo Vespucci. But Amerigo wasn’t the first person to explore these continents.

There were already people living there when he arrived. Still, “America” was named after Amerigo. For the most part, people name things because they are claiming possession of a place. Because of that, sometimes the original names of places are lost or erased.

That’s what I found out from my friend Theresa Jordan, a history professor who teaches a geography course at Washington State University.

I also found out that Native Americans in the northeast of North America were already calling the place they lived “Turtle Island.” The Guna people, the first to live in Panama and Columbia, called the Americas “Abya Yala.”

The names of places can also come from stories, legends, or myths. “Europe” comes from a Greek myth about a princess called Europa. One of Jupiter’s moons is also named after Europa.

“Asia” originated from another Greek story about the east coast of the Aegean Sea, which is near the place we today call Greece. We still don’t really know the origin of the name “Africa.”

Meanwhile, some places are named after leaders or people in power. Sometimes we will take a person’s full name and put a twist on it. For example, the state of Georgia is named after the English King George the II. Louisiana is named after Louis XIV, king of France. Washington state was named after our first president, George Washington.

Believe it or not, some people have different names for the same place. For example, people in the U.S. might call a country South Korea, but the people who live in South Korea call their country Hanguk.

People in Japan or China might call it Chosŏn. It’s a good reminder that people look at the world through different lenses, or worldviews.

In fact, if we looked at maps around the world they might look very different depending on where were visiting. In a classroom in China, you might find that the country is in the middle of the map rather than to the left as it is in U.S. classroom maps.

Jordan said it’s great to think about questions like the one you’ve asked. In fact, historians and researchers think about these kinds of questions a lot.

“Who is writing the history? Who’s history are you reading?” Jordan said. “As historians we always have to be asking those questions.”

Those are good questions for all of us to ask, too. Who knows, maybe one day you’ll study history or geography to help us understand more about the past and work to help shape our future.

Dr. Universe

Ask Dr. Universe – Cows’ Milk

Dr. Universe: How do cows make milk? How do humans get milk from a cow? – John, 4, Colton, Ore.

Dear John,

Quite a few things have to happen for a cow to make milk. First, the cow has to eat lots of food, such as hay, grass, or grain. You may have heard that a cow will regurgitate her food, or sort of spit it up, and then chew on it again.

A cow will chew this mashed up food, or her cud, so she can get all the good stuff out of it—protein, sugar, fat, vitamins, and other nutrients. Milk is actually mostly water, plus those good nutrients.

That’s what I found out from my friend Amber Adams-Progar, an animal scientist at Washington State University who studies cow behavior.

When the cow eats, those nutrients get absorbed into the cow’s bloodstream. The bloodstream is like a highway that moves the nutrients around the body.

In particular, the bloodstream helps deliver nutrients to the cow’s udder, which hangs down under the cow’s belly near her hind legs. It’s here in the udder where the milk is made.

Believe it or not, the cow’s brain is also involved in producing milk. When a cow’s body senses that she is going to have a baby, the brain will release certain chemicals. The chemicals help send out a signal for her body to produce milk.

When a calf is born, it will reach up to its mother’s udder to drink some milk. The milk has a lot of good ingredients the calf needs to grow up strong and healthy.

Of course, a cow doesn’t always have milk in her udder. She will only produce it when she has a baby. A cow has live young, hair, and produces milk. That makes her a mammal. There are more than 5,000 mammals on our planet. You are a mammal, too.

Humans have actually been using milk from cows for thousands of years. They even figured out how to turn that milk into ice cream, butter, and cheese.

In the past, some farmers would milk cows by hand and collect milk in small buckets. These days, some farmers use milking machines. They want to keep everything sanitary. They clean the cow’s udder and clean the milking equipment.

Most milking machines have about four cups which attach to a cow’s udder. These cups use suction to help release the milk. The milk flows down into a tube and gets collected in a huge tank. The person who is milking the cow will then clean the udder and milking equipment.

Adams-Progar also told me that some milking machines actually rely on robotics. On some farms, a cow can choose what time of the day she wants to go to the milking machine. A robot’s laser technology will line up her udder with the cups. Meanwhile, tiny sensors can help track her behavior.

You might say that a jug of milk all starts with a mama cow eating dinner. It’s something to think about the next time you go to the grocery store.

Dr. Universe

Ask Dr. Universe – Eyebrows

Why do we have eyebrows? -Zach, 11, Kettle Falls, Wash.

Dear Zach,

Humans have hair on their heads, arms, and as you mention, even the face. If you feel your face, you might feel some small, fuzzy hairs on your cheeks and forehead. But the hair of your eyebrows is usually a bit thicker.

I asked my friend Mark Mansperger why we have eyebrows. He’s an anthropologist at Washington State University.

Eyebrows appear to serve two main purposes, he said. One of the purposes of eyebrows is to keep things like rain or sweat from rolling down your forehead and into your eyes.

“It guards your eyes in that way,” Mansperger says.

All the hairs on your body grow out of tiny holes on the skin called follicles. Each follicle can grow a single strand of hair. There are tiny little blood vessels in the skin that give the root of the follicle everything a hair needs to grow.

The human body isn’t perfectly symmetrical. Sometimes one eye or eyebrow might look a bit different from the other. Everyone’s eyebrows are just a little bit different.

Some eyebrows might be brown, blonde, black, or red. People who have had eyebrows for a long time might have hair that is gray or white. The eyebrows might be really thick or very thin.

You may have also noticed that some people have just one eyebrow. Scientists have discovered one of the indicators in human DNA that will help determine if someone will grow a unibrow.

Meanwhile, some people’s genes don’t have the typical instructions for growing hair. They have something called alopecia. Alopecia occurs when the body’s immune system attacks hair follicles. People will often lose their hair, including their eyebrows.

Eyebrows can also play a part in communication. The muscles inside your face and the hair on the outside can help you make all kinds of facial expressions. A furrowed brow might communicate that you are angry or concerned. Raising your eyebrows might let someone know you are surprised or maybe disapproving.

As Mansperger summed it up, eyebrows serve important functions. They help protect our eyeballs and communicate to those around us.

Finally, eyebrows can also be a bit entertaining. Some people have the talent of raising just one eyebrow at a time or making their eyebrows do a kind of dance. A lot of people can actually train their eyebrows to move using the muscles in their faces. While some people are naturals, others require quite a bit of practice. These 100 kids gave it a try. Maybe you’ll try it out, too.

Dr. Universe

Ask Dr. Universe – Poisonous Bugs

Dr. Universe: How do bugs have poison? – Wyatt, 11, New Zealand

Dear Wyatt,

There are all kinds of insects crawling and flying around our planet. And you’re right, some of them—but not all of them—are poisonous.

I learned all about poisonous insects from my friend David James. James is a researcher at Washington State University who is very curious about monarch butterflies.

Monarchs can actually eat plants that would be poisonous to most other animals. After a monarch caterpillar hatches, it will eat its own eggshell. Once it runs out of eggshell, it will start chomping on the poisonous milkweed plant. But it doesn’t cause the insect any harm.

In fact, monarchs need milkweed to help them grow and become a butterfly. Later, the butterfly will use the milkweed plant as the perfect spot to lay its eggs. That way when new caterpillars hatch and finish up their eggshell, they will have milkweed to eat.

When monarchs eat poisonous milkweed, the chemicals in the plant help form poison in their bodies. These chemicals are called toxins. When an animal inhales, touches, or eats a toxic creature, they can experience the effects of poison. It can be deadly, but sometimes it just makes the animal sick.

If a bird eats a monarch, they might throw it up or spit out the butterfly. The predator probably won’t try to eat another monarch in the future. That poison can help the monarch species survive in the long run.

Milkweed and monarchs have actually been helping each other survive for a long time. The plant provides food for the butterfly. Meanwhile, the butterflies help move pollen around to help new milkweed plants grow.

It turns out that different insects can get their poison with help from different plants. The cabbage white butterfly caterpillar, for example, eats a lot of cabbage.

The cabbage white uses a combination of chemicals from the cabbage to produce a toxin in its own body. They can actually secrete the poison from their hairs, or setae. If you look under a microscope, you would see little droplets that look like oil on their hairs, James explained.

Of course, humans don’t produce toxins from their hairs when they eat cabbage. Instead, they usually just get a lot of nutrients and fiber. Different toxins can impact different species in different ways.

You might also be interested to learn that venom is a bit different from poison. Venom is usually a kind of toxin injected through stinging or biting. If you get a bee sting or spider bite, you are experiencing the effects of their venom.

Whether an animal is venomous or poisonous, it will often use its bright colors or patterns to warn a predator. For example, monarch butterflies have orange and black patterns on their wings. The monarch caterpillars are yellow with white and black striped bands.

These brilliant colors can help send a message to predators like, “Don’t eat me, I’m poisonous!” It’s a helpful reminder for the predators and can help insect species survive.

Dr. Universe

Ask Dr. Universe – Snake Senses

Dr. Universe: If snakes smell with their tongues, what do they do with their noses? – A.J., 5, Kennewick, WA

Dear A.J.,

You’re right, snakes have an amazing sense of smell. They can use their tongues to pick up on all kinds of scents in the air.

Whenever we smell something in the air, we are actually sniffing tiny building blocks called molecules. These molecules are what make up the scents of everything around us—things like baked bread, fresh-cut grass, and warm cookies.

If you were a snake, you might sniff out the scent of a slug or mouse. You’d use your tongue to pull the molecules from the air into your mouth.

Then those molecules would reach a part of the roof of your mouth called the Jacobson’s organ. This organ helps de-code the molecules into smells. The smell might help you find some prey or let you know to slither away from a predator.

I learned all about snakes from my friend Rocky Parker. Parker graduated from Washington State University and is currently an assistant professor at James Madison University in Virginia. He is very curious about how snakes use their senses.

While the tongue does most of the smelling, snakes also use their nostrils to take in odors. Parker said we are still learning exactly how snakes use their nostrils, tongues, and Jacobson’s organs to smell the world. But we do know that some other kinds of animals use all these parts to smell, as well.

Lizards will flick their tongues in different patterns to collect odors from the air. Elk and deer will stick their noses up in the air and lift their upper lips to transfer some molecules inside their mouths. It gives them a kind of “sixth sense” that helps them know their world, said Parker.

Of course, a snake’s nose is important for more than just helping with their sense of smell. Like pretty much all animals, snakes need a healthy supply of oxygen to survive. The nostrils are oxygen’s way into the body. Oxygen is really important to animals because it helps them produce fuel for their bodies.

Our planet is home to about 3,600 different species of snakes, so we see different snakes with different kinds of lungs. But for the most part, snakes only breathe through one lung.

In most snakes, the left lung is usually smaller or missing completely. It’s a kind of leftover part from their ancestors and doesn’t work for breathing. The right one that runs along their long, tubular bodies is what helps them breathe.

Even though humans can’t smell with their tongues, all of their five senses are powerful tools for navigating the world. Have you ever thought about becoming a scientist one day? With great questions like these, I’m getting the sense that you are well on your way.

Dr. Universe

Ask Dr. Universe – Brain Dead

Dr. Universe: What does it mean to go brain dead? – Noelle, 10, Sumner, WA

Dear Noelle,

Let’s say we wanted to find out what kind of electrical activity was happening inside your brain at this very moment. Yep, you read that right: your brain is full of electricity. It actually generates enough electricity to power a lightbulb.

In fact, the tiny cells in your body use electricity to send messages to each other. That’s part of what helps the brain and body communicate. I decided to visit my friend Samantha Gizerian, a neuroscientist at Washington State University, to find out more about our brains.

She said if we wanted to observe activity in a human brain, we could do a test called an electroencephalogram (uh-lek-trow-uhn-seh-ful-luh-gram), or EEG for short. We’d attach some small discs with thin wires, or electrodes, to a person’s head.

Then we could watch as a computer translated that brain activity into spikes and dips on a screen. Scientists can look for patterns on the screen to learn more about our active brains. But we can also use this test to help us find out if someone is “brain dead.”

Perhaps you’ve heard a person say that they were feeling “brain dead” if they made a mistake or maybe forgot to do something. But when someone is actually “brain dead” it means that the electrical connections between cells have stopped working altogether. We wouldn’t see any spikes and dips from the EEG on the computer screen.

That’s a lot different from a coma. A person in a coma is alive, but unable to respond to or interact with the environment around them. Brain death usually happens when the brain stem at the bottom of the brain dies. If the brain stem isn’t functioning anymore, a person can’t survive.

Along with EEG tests, doctors will also test patient reflexes to see if they will respond to pain, if their pupils move when they shine light, or if their heart rate and body temperature start to drop when they remove some of the technology that helps keep the lungs breathing or the heart beating.

“The reason they do all these tests is because any one on its own could still happen when the patient is alive,” she said.

Gizerian said these tests are really important for making sure people follow medical laws, too. When doctors first started doing surgeries to take out people’s organs for transplants, they wanted to make certain a person’s brain was no longer working. It turns out the term “brain dead” actually has more to do more with laws than anatomy.

When someone dies, the organs in their body can sometimes still help other people who need an organ to survive. There are a lot of organs that have been transplanted over the years—hearts, liver, lungs, kidneys. But we’ve still yet to learn how to transplant the brain.

In fact, there’s still quite a lot we don’t know about the brain. Who knows, maybe one day you will use your own brain to investigate all kinds of questions about that three-pound organ between our ears.

Dr. Universe

Ask Dr. Universe – Too Much TV

Dr. Universe: My mom says video games and too much TV rot my brain. What does that mean? How does that happen? Does my brain turn to slime? – Tree Family Kids, 3, 5, 7, Dundee, Michigan

Dear Tree Family,

If you play video games or watch too much television, you don’t have to worry about your brain actually turning to slime. But it is true that some video games and television shows can take away some of your energy without giving you much in return.

When we are not being active with our bodies, too much screen time can wear us down. It not only wears down the brain, but also the body. And at the same time, some video games and stories can often help us learn better.

That’s what I found out from my friend Jonah Firestone, a researcher at Washington State University who knows a lot about virtual reality, video games, and learning.

In his lab, he’s studied how kids learn when they get to experience a virtual reality, such as an environment like the ocean. They put on goggles and are transported to a computer-generated and three-dimensional scene of life in the sea. If they try to touch the animals in the ocean, the animals might swim away if the person gets too close.

As you might imagine, these types of interactive, virtual worlds are a much different way to learn than reading or writing about the ocean. Firestone told me that different parts of the brain fire up when we learn in different ways. We can learn through things like writing, reading, or experiencing something in person.

When you have a full-body learning experience with virtual reality, the brain is much more active than if you just listen to something or copy it down on paper.

If you are anything like me, you might really enjoy playing video games or watching television. It might be relaxing and fun. If you are interested in either one, you might even try developing a story line or creating a game of your own.

Firestone said that there are a lot of easy ways to make videos with smart phones. You might even use Legos to make stop-motion videos. Apps like Scratch also make it possible to make games and tell stories on a computer.

When your mom says “rot,” she might be thinking about a few different things that can cause the brain and body to wear down. A bright screen can sometimes mess with the body’s sleep signals, which can throw off our sleep schedules. Too much screen time might make your eyes or body tired. You can help counteract this and get more energy by doing some stretches, jumping jacks, and moving around. Or by going outside and playing!

“Balance it out with doing something different—something active,” Firestone said. “If you can move around, be artistic, engage your imagination, be creative, or read, you can counteract this supposed ‘rot’.”

While there are some ways a brain can literally rot or turn to slime, watching video games or television isn’t one of them. But I suppose that’s a question for another time. In the meantime, if you might try making some slime of your own.

Dr. Universe

Ask Dr. Universe – How Trees Help the Air

Dr. Universe: How do trees help the air? – Ella, 12

Dear Ella,

Take a big, deep breath. As you inhale and exhale, you can probably feel the air taking up space in your lungs.

The air we breathe is made up of a few different things. It includes gases such as nitrogen, oxygen, and carbon dioxide—just to name a few. Animals breathe in oxygen and breathe out carbon dioxide. But in the plant world, it’s the opposite.

Trees, plants, and even algae in the ocean, take in carbon dioxide from the air and, using the energy of the sun, transform it into the oxygen we all breathe. That’s what I found out from my friend Kevin Zobrist, a forestry professor at Washington State University.

Zobrist told me that process is called photosynthesis. It’s the way plants recycle carbon dioxide while also making their own food and energy.

Sometimes particles get mixed into the air that aren’t very good for us. They are so small we can’t see them, but they can sometimes irritate people’s airways or create health problems.

The good news: Trees are really good at helping catch and filter out these particles from the air.

Scientists have also found that trees with leaves that have tiny hairs on them are especially good at grabbing onto some of those particles and removing them from the air. I also discovered that some trees also capture particles in their bark, so animals like us don’t have to breathe them in.

It’s really important to have clean air to breathe. After all, the average human will inhale and exhale about 7 or 8 liters of air every minute or so. That adds up to each person breathing about 11,000 liters—or about 2,905 gallons, think milk jugs—of air each day.

Trees can also help cool the air. When it warms up outside and water from the surface of the leaves evaporates, it can take some heat out of the air. Meanwhile, trees can help capture dust and even smoke from wildfires.

While trees help store a lot of carbon within themselves, that doesn’t mean they can store it forever. When trees burn during wildfires, they release carbon dioxide back into the atmosphere, along with lots of harmful smoke particles. Trees help the air, except when they are on fire, Zobrist said. Carbon dioxide also comes from burning fossil fuels, such as the gasoline we put in cars.

For the most part, trees do their best to help the air stay cool and clean. They also make a great shady place to take a nap. You know, I think I’ll go find a nice spot to relax under a big tree. Thanks to your question, I will be reminded how important it is to take care of the trees that also take care of us all.

Dr. Universe

Ask Dr. Universe – Different Accents

Dr. Universe: Why do people have different accents? Why do we have them and need them? -Florrie P., 9, UK

Dear Florrie,

Whether you say hello, ‘ello, hey ya’ll, toe-may-toe or toe-ma-toe, we all have a kind of accent that often comes from where we live or who lives around us.

That’s what I found out from my friend Nancy Bell, a Washington State University professor who is really curious about the way language works. She told me more about why we have accents and why we need them.

There are a lot of different accents. You might have friends who speak English but have a Scottish, Irish, Australian, or French accent.

Even in the U.S., there are many accents from the east to the west to the mid-west to the south. In those regions, people also speak many types of English such as Chicano English, African American English, or Indian English.

A lot of times when you see a difference in the way people talk, there is also some kind of physical barrier between them. This might be something like a mountain, a river, or the Atlantic Ocean that separates you and me. When groups of people are isolated from each other, they develop unique ways of speaking, including accents and whole new languages.

We also have social barriers, Bell said. We sometimes see differences in the way people talk when groups are segregated from each other. These social barriers still persist today.

You might wonder why there are still accents if people can travel more easily over mountains and oceans and since there isn’t as much segregation as there has been in the past.

“Why don’t different accents disappear?” Nancy asked me. “It’s part of identity. The way we speak instructs and signals to other people who we are.”

I don’t know about you, but sometimes I find myself being a bit of a copycat when I hear someone with an accent different than mine. I start speaking with their accent, too.

Bell said this is a phenomenon called speech accommodation. It usually happens when you like the other person and want to find common ground. The opposite can also happen. You can find yourself trying to steer far away from someone’s accent if you don’t really get along.

We can also learn new accents—just think about actors who have to use an accent different than their own. We can also lose our accents after we’ve lived in a different place for a long time, too.

While a lot of people have accents depending on where they live or the way people around them speak, they also have their own personal way of speaking. It’s called an idiolect—and our accents are just one part of it.

The different ways we pronounce things, the sentences we string together, and the vocabulary we have can help us express ourselves, our identities, and feel connected to our culture. All that diversity is a good thing, so don’t let the cat get your tongue.

Dr. Universe

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Ask Dr. Universe – Nightmares

Dr. Universe: Why do we have nightmares? -Kourtney, California,  10

Dear Kourtney,

You are running through the woods and a bear is chasing you, when all of a sudden you wake up in your bed and realize it was just a scary dream. Our nightmares can sometimes feel super scary, even if what’s happening isn’t real.

Fear is a natural part of being a human. In fact, you may have even felt shaky or sweaty after waking up from a bad dream. It’s all part of something we call the fight or flight response.

When humans are faced with something scary, this response helps them decide if they should face their fears and fight or run away by taking flight. This fight or flight response works even when you are asleep.

When humans fall asleep, they cycle through different phases of sleep. During one of these phases, called Rapid Eye Movement (REM) sleep, their eyes are moving rapidly under their eyelids, the brain is very active, and most people report dreaming. This type of sleep first happens about an hour and a half after you fall asleep and then again every 90 minutes or so throughout the night.

That’s what I found out from my friend Willie Vanderheyden, a researcher at Washington State University who studies sleep. He’s curious about the types of things that can disturb our sleep, too.

He told me that the real answer to your question is that we don’t know exactly why we have nightmares, or dreams, for that matter. After all, it’s hard for someone to be dreaming and report what they are dreaming at the same time. But scientists have a few ideas.

We may get nightmares after we’ve experienced something that made us afraid. For example, watching a scary movie before bed or seeing something scary happen during the day.

We may also get nightmares because of something coming up that makes us anxious. For example, we might be giving a big speech at school. Nightmares may be a way for us to process the day, prepare us for something in the future, or help us look at problems in our lives from different angles.

People have different fears, so they have different types of nightmares. Maybe you had nightmares about monsters or imaginary creatures when you were little. But maybe as you grow up, they are about more real fears like heights or natural disasters.

Vanderheyden told me it’s actually pretty common for kids to get nightmares. They sometimes get them even more than adults do. But we still don’t really know why that is.

“Sleep is something that everyone does, but we still don’t know why,” Vanderheyden said. “Everyone thinks we have it very figured out. But we actually know very little about it.”

That’s part of the reason he is so curious to learn more about how sleep works. Who knows, maybe one day you can help us learn more about nightmares and why we get them, too. Until then, keep dreaming up great questions.

Dr. Universe

Ask Dr. Universe – Different Tastes in Music

Dr. Universe: Why do people like different kinds of music? – Skyler, 14, Michigan

Dear Skyler,

When I got your question, it was music to my ears. Humans have been experimenting with all kinds of sounds, lyrics, and instruments for thousands of years.

There are hundreds of genres of music, so while you might like one kind, a friend might like something completely different. Or maybe you became friends because of your similar taste in music.

My friend Horace Alexander Young is a musician and professor at Washington State University. When I went to visit him, he had been practicing his saxophone and offered to help out with an answer to your question.

Part of the answer is that everybody has an image of themselves in their head and has different ways they express themselves, he explained. Music can be a part of our identity—the set of qualities and beliefs that make us who we are.

At the same time, music can also help us feel like part of a group or a culture, especially one that shares an interest in a certain kind of music. Maybe you are part of a friend or family group that likes pop or hip hop or metal or classical.

Music can also be nostalgic, that is, it creates a kind of longing for the past. Young said that musicians leave behind a footprint with their music. They leave a permanent mark in people’s lives. Even long after the musicians are gone, people still find something in the musicians’ recordings that they can enjoy.

You may also find that the music you like is strongly tied to your memory. Maybe there was a song that someone sang to you when you were little that brings up good memories. On the other hand, you might also find that music can bring up sad memories.

When we listen to music that we like, a chemical called dopamine is sometimes released in the brain, which can make us feel good. We might want to listen to a song on repeat.

“We can hear music and like it or not like it, but sometimes it can be life-changing,” Young said. “It becomes a mirror that we are holding up.”

There are even some algorithms today that can help pick up on the kind of music you like. When you are streaming music, some programs will let you like or dislike songs. The technology learns to pick up on the kinds of things you like to hear.

I’ve also observed that people’s taste in music can remain the same their whole life or it can change many times.

But the truth is, we don’t know all the exact answers to why people like different kinds of music—or sports, or food, or colors. There are lots of different factors that can influence our preferences. We are all different people who like different things. Whether we are listening or playing music, we can express ourselves and also learn from each other.

Dr. Universe

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Ask Dr. Universe – Why Dogs Are Important to Humans

Dr. Universe: Why are dogs important to humans? Stephani R., 9, Washington State

Dear Stephani,

Dogs are important to humans in all kinds of ways. The connection between the two goes back thousands of years.

Dogs have had all kinds of jobs. They work on farms where they guard the land and also round up livestock like sheep and cows. Dogs also provide humans with company. Just petting a dog can create a real physical change in the human body.

That’s what I found out from my friend Alexa Carr, a Washington State University researcher who investigates the bonds between animals and humans.

Along with fellow scientists, she has discovered that when people pet a dog, they have fewer stress chemicals in their body—hormones called cortisol. We also know that when a person is looking into a dog’s eyes the body also releases a kind of chemical that is linked to love and connection with another being.

Dogs can also help humans navigate their world. They help guide people who have lost their sight. They assist people who have diabetes or seizures. A lot of service dogs can sense when something is wrong and alert their owners. Some of them can even open fridges and bring food to their human.

A dog can use its sensitive nose to help humans, too. At airports, some dogs sniff out luggage to make sure people aren’t bringing anything they shouldn’t on the plane. In some cases, dogs can even sniff out cancer in people.

It turns out there are also dogs on our planet that help scientists, Carr said. They sniff out animal poop to help scientists learn more about different species. We can learn a lot from the DNA we find in an animal’s poop. Some dogs sniff out orca poop that floats in the ocean to help us learn more about the whales.

Dogs are there for us when we lose someone we love and often look at us when we talk to them. They are also good at helping people, including veterans, with their mental health. Carr said there are a lot of factors that go into understanding how humans and dogs work together. We are still learning a lot about the relationship.

“People are important to dogs, too,” she said. “It is a relationship that goes both ways.”

People can give dogs ear scratches, take them to the park, feed them, and walk them. Taking a dog for a walk can also help a human get exercise and stay healthy. While I may be a little biased when it comes to all things cats, it’s no wonder dogs really are your best friends.

What do dogs do to help in your life? Why are they important to you? Tell us about it sometime at Dr.Universe@wsu.edu.

Dr. Universe

Ask Dr. Universe – Why Sea Turtles Can’t Retract into Their Shells

Dr. Universe: Why can’t sea turtles pull back into their shell? I was at the Saint Louis Zoo and they said tortoises and other turtles can pull back into their shells. – Tyler, 7, Missouri

Dear Tyler,

There are more than 350 species of turtles that live on our planet. While many of these turtles live on land, others live in the sea.

Depending on where a turtle lives, its body will be a little different. Turtles have adapted to live in different environments and they have traits that help them survive in those places. As you mentioned, a lot of turtles and tortoises on land have the ability to pull, or retract, their head into their body.

Because turtles move really slow, the ability to retract their head offers them protection from more speedy predators. Their hard shell can help shield them from danger and prevents them from becoming someone’s dinner.

My friend Abbey Hayes is a graduate student at Washington State University who mainly studies insects, but she’s also studied green sea turtles off the coast of Mexico. Green sea turtles are just one of seven different species of sea turtles. The others are hawksbill, Kemp’s ridley, leatherback, loggerhead, the olive ridley, and the flatback.

Sea turtles have certain traits that help them live in the sea. Instead of having an arched shell like a land turtle, their shell is flattened to help them move more quickly and easily through the ocean. They also have longer legs than land turtles and have evolved paddle-like flippers. Hayes said that sea turtles just don’t have as much space inside their bodies to retract their limbs and heads.

I also found out that a turtle’s hard shell is actually made up from about 50 bones. Scientists used to think that turtle shells evolved from scales, but some scientists now think those shells evolved from ribs. One sea turtle called the leatherback is a kind of sea turtle that doesn’t have a hard shell, but instead a thin layer of rubbery skin that has thousands of tiny bone plates.

It turns out that a lot of these sea turtles are threatened or endangered because of human actions. Because sea turtles can’t pull their heads into their bodies, they can be more vulnerable to predators and other kinds of threats, such as getting tangled up in fishing nets and the trash people toss into the sea.

And while it may be tempting to pet a sea turtle if you see one, Abbey reminded me that it is important to respect animals, especially in their natural habitat. She also told me that if you go swimming in the ocean, it is important to pick reef-safe sunscreens that are safe for animals like corals and turtles.

Instead of hiding in a shell, a sea turtle has the ability to move with speed and also has a lot of agility that lets it quickly escape predators, like whales or sharks. These skills can help them stick their neck out and survive in the ocean.

Dr. Universe

Ask Dr. Universe – How the Moon Glows

Dr. Universe: How does the moon glow? -Reece, Pullman, Wash.

Dear Reece,

Our moon is one of the brightest objects in the night sky. But unlike a lamp or our sun, the moon doesn’t produce its own light.

Light can travel in lots of different ways. Moonlight is actually sunlight that shines on the moon and bounces off. The light reflects off old volcanoes, craters, and lava flows on the moon’s surface.

That’s what I found out from my friend Julie Menard, a researcher at Washington State University who studies what makes up the rocky planets in our solar system.

If you look through binoculars or a telescope, you might even be able to see some lunar rays coming out of the moon’s craters, she said. These craters are places where asteroids or meteorites hit the moon long ago. The rays are formed by rocks and dust and other stuff that got blown out of the crater by a meteorite. You might also see some lighter, brighter spots on the moon, which are signs of newer impacts.

Menard also reminded me about a common object a lot of us use: mirrors. She said that during the Apollo missions, astronauts actually left behind some mirrors on the surface of the moon.

The moon landing was 50 years ago, but the mirrors are still up there helping us learn new things. These days, scientists can use lasers and those mirrors to help us measure the distance between the moon and the earth. There’s about 238,900 miles between us.

You may have noticed that it can look like part of the moon is missing at times. But don’t worry, it’s always there. There are eight phases: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent.

You may also have heard about the “dark side of the moon.” The moon spins on its axis in the same amount of time that it orbits Earth, so we only ever see one side of the moon. The other side is “dark” to us, but that side of the moon still gets light.

When I look up to the moon, sometimes I see different shapes in it like a face or a smile. In Chinese and other Asian cultures, there is even a story about a rabbit on the surface of the moon. These shapes that we see in the dark and light parts of the moon are known as lunar pareidolia, a word that means our minds find meaningful shapes where there are none.

If you’re anything like me and enjoy watching the night sky, you might even try tracking moon phases yourself. All you’ll need is something to write with and a piece of paper. Each day, draw a picture of the moon and see how its reflection changes.

As you see the moonlight shine down and illuminate the night sky, remember that this night light wouldn’t be possible without help from the biggest object in the solar system—our sun.

Dr. Universe

Ask Dr. Universe – Why People Dance

Dear Dr. Universe: Why do we dance? – Helen H., 11, California

Dear Helen,

If we traveled around the world, we would see all kinds of dancers. We might see classical ballerinas in Russia. We might see break dancers performing on the streets of New York. We might even see tango dancers in Argentina.

While the exact reasons we dance remain a mystery, there are a few theories about it.

That’s what I found out from my friend Ed Hagen, an anthropologist at Washington State University who has researched the roots of dance.

In nature, we actually see a lot of animals dancing. It’s not just humans. Bees do a kind of waggle dance where they step  in a figure-eight pattern. This movement helps them communicate important information. It lets other bees know where to find the best pollen to make honey.

Birds, especially male birds, will often flutter their bright and beautiful feathers to attract a mate. Dolphins will also make graceful leaps together and twirl around in the ocean to attract a partner.

This process of using dance to find a mate is part of something called courtship, Hagen said. Dance may also be part of courtship in humans, too. A good dance could be a signal that your partner is intelligent, has the ability to perform a skill, and might even be able to pass these traits down to the next generation.

Of course, people still dance even if they aren’t looking for a mate. One other idea about why humans dance is that early humans used movement to signal that a certain place was part of their territory.

A lot of animals, like lions and coyotes, also use movement or sound to signal to others: “This is our land. Don’t mess with us.”

While dancing may be rooted in courtship or protecting what’s yours, we dance for many reasons today: celebration, competition, and even exercise.

I also talked to my friend Kaila Evenoff, coach of the WSU Crimson Girls dance team, to find out more about it.

“Dance is a form of expression and a form of art,” she said. “We can convey our emotions into movement without talking.”

We can plan, or choreograph, these movements, too. When the team performs at football games, they help lift the crowd’s spirits. They also compete against other dance teams around the country to see who has the best skills.

Even if you aren’t a professional dancer, dancing can be a good form of exercise, too. It helps the body produce endorphins, or brain chemicals that make us feel happy.

“It is really enjoyable,” Hagen said. “That opens the question, why is it enjoyable?”

The types of dances we do change throughout time, too. In fact, humans come up with new dance moves all the time. I’ll have to see if I can come up with any good ones.

Maybe one day you can put on your dancing shoes and thinking cap to help us learn even more about what it means to dance.

Dr. Universe

Ask Dr. Universe – Mummies

Dr. Universe: How do you make mummies? -Michael, 7, Arizona

Dear Michael,

When we think of mummies, we might imagine the kind from ancient Egypt wrapped up in linen. But there are lots of ways to make mummies—and they can even form in nature.

That’s what I found out from my friend Shannon Tushingham, an archaeologist at Washington State University and director of the WSU Museum of Anthropology.

In ancient Egypt, priests were usually in charge of making a mummy. They used a special hook to pull out the brain. They put the brain in a jar to help preserve it. They put the lungs, liver, intestines, and stomach in jars, too. But the heart was left in place.

The ancient Egyptians believed it was the heart, not the brain, that was the center of someone’s being and intelligence.

They also used a lot of salt to preserve the body, more linens to help the body keep its shape, and several yards of linen strips to wrap the body from head to toe.

“They had this down to a science,” Tushingham said, who was inspired as a kid when she got to see King Tut’s mummy.

The whole process of making a mummy would take about 70 days. But the making of a mummy was about more than just preserving a body. The ancient Egyptians also believed they were preparing someone for an after-life.

Along with the jars of organs, people would place items with the mummy like furniture, food, games, and other things their loved one might enjoy. The mummy might also get a decorative mask or be put in a stone case called a sarcophagus.

We have learned a lot about the process from hieroglyphics, the symbols that Egyptians used to write. The stories they wrote also tell us about mummified baboons, beetles, falcons, crocodiles, and lots and lots of cats, who they worshiped. Just saying.

Tushingham said we can also find mummies out in nature. One mummy that archaeologists get excited about is Ötzi, otherwise known as the Iceman.

He died in the mountains about 5,000 years ago and his body has been well-preserved. They even found a little bit of brain tissue. You can see his tattoos and archeologists even studied his hair, which had clues about what he liked to eat.

Researchers have also found mummies in bogs, or wetlands that have a lot of moss. These bogs can be found everywhere from Denmark to Florida and sometimes conditions can be just right to mummify a body. These mummies have been called “bog bodies.”

While we’ve found mummies in Egyptian tombs, we’ve also found them underground. The hot, dry conditions and chemistry of the dirt can help preserve bodies, too. Tushingham added that archeologists take great care when working with mummies or any kind of remains. The bodies are sacred, she said, and we are still finding them today.

Perhaps one day you’ll become an archeologist and find mummy or study hieroglyphics to help us learn even more about life in the past.

Dr. Universe

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Ask Dr. Universe – Whales’ IQ

Hi Dr. Universe: Are whales smart? -Tishawnie P., 9, Massachusetts

Dear Tishawnie,

Whales can learn to do all kinds of amazing things. Humpback whales learn how to blow bubbles and work together to hunt for fish. Dolphins, a kind of toothed whale, teach their babies different sounds. It’s a kind of language the young dolphin will know for life.

But to find out just how smart whales really are, I asked my friend Enrico Pirotta, a Washington State University researcher who studies how blue whales make long journeys across the ocean.

Before he revealed the answer to your question, he shared a bit more about intelligence. Usually people talk about intelligence as the ability to learn something and apply what they learn, he said. It can be tricky to compare our intelligence with other animals, but it’s something some scientists think about.

“There is not an IQ test we can do with whales,” Pirotta said.

Whales have instincts. They follow their moms, go to the surface to breathe, but they can also learn. They have a pretty high level of intelligence when compared to a lot of other animals, he adds.

Pirotta told me that if we were in Australia, we might even see some dolphins who learn to carry sea sponges on their beak. They do this to protect their beaks from getting poked by critters or sharp pieces of coral while they search around for food in the sand.

It’s also important to note that what we know about whale intelligence comes mostly from studying those in captivity, especially dolphins. We still don’t know as much about wild whales, but Enrico said that the studies we do have are showing that the wild whales are likely just as intelligent.

Whales have pretty big brains. In fact, the largest brain on the planet belongs to the sperm whale. The sperm whale brain weighs about five times as much as a human brain. But just because you have a big brain doesn’t necessarily make you smarter.

However, we do know that animals that have a big brain compared to their body do tend to have a certain kind of intelligence. One particular thing scientists look at when studying intelligence has to do with special cells that help animals process information. They are called spindle neurons and they’ve been found in humans, elephants, and apes, too. Scientists have found connections between these parts and an animal’s ability to learn and apply knowledge.

Pirotta also said that some animals like whales also appear to have something called emotional intelligence. They can show signs of empathy, grief, joy, and playfulness. All of these learned behaviors, types of intelligence, and signs of teamwork have led scientists to think about groups of whales in new ways, too.

“We now believe this qualifies as a form of culture,” Pirotta said.

Who knows? Maybe one day you will use your own human intelligence to study whales and help us learn more about whale culture and what’s going on inside their brains.

Dr. Universe

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Ask Dr. Universe – How We Talk

Dear Dr. Universe: How do we talk? – Emmy, 7, Wash. State

Dear Emmy,

When you were a little kid, maybe you played Peek-a-Boo or sang “Itsy Bitsy Spider.” These kinds of games and songs have a lot of the different sounds we make when we are first developing speech.

A lot of humans start out playing with speech through cooing and crying. At about six months old, this cooing and crying turns to babbling. A baby might make sounds such as ma-ma, pa-pa, or ba-ba.

Words first start to develop around a baby’s first birthday. That’s what I found out from my friend Georgina Lynch, a speech language pathologist and clinical researcher at Washington State University.

“Kids begin to put two or more words together at about the age of two, but the magic comes when a child acquires their first 50 words,” she said.

Then they can use those words to communicate their ideas. Little kids build up those sounds and words as they watch their caregivers, observe their environment, and repeat things their caregivers say to them.

Lynch also told me about something called the speech chain, which helps us make sense of sounds. The sounds you hear come through your ears but the sound is processed in the left side of your brain. Here, the vibrations that make up sounds get translated into the information you need for language, forming meaning for individual speech sounds. Meanwhile, the right side of the brain sends signals to muscles in our faces and mouth to help produce sound.

Lynch told me that eye contact, or visual attention, is also important when speaking. Humans often look at what they are they talking about, such as pictures in a book or at objects. It’s how they learn which sounds go with the things they see.

Lynch works with kids who have autism and often have a hard time with visual attention and learning to speak. Lynch came up with an idea to study eye-movement and the brain and is helping us learn more about children with autism using technology and eye-tracking cameras.

It’s important to remember people can communicate in different ways. At WSU, Lynch teaches future speech-language pathologists who work in a clinic where they see kids of all ages who have lots of different needs when it comes to speech.

She also told me that some kids may never be able to have verbal speech—that is, they don’t talk out loud with words. Instead, they might use a tablet or a computer program to help them generate words and communicate their thoughts and feelings by having the computer speak for them.

You might also see some people using their hands and facial expressions to communicate with sign language. Here is how you can say “cat” in American Sign Language. It’s kind of like drawing some whiskers in the air with your fingers.

It takes the work of the brain, eyes, ears, mouth, and muscles in the face to make speech. And while the first 50 words are key to sharing your thoughts and ideas, the dictionary has more than 171, 476 words you can try out in your lifetime.

Dr. Universe

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Ask Dr. Universe – Bags Under Our Eyes

Dr. Universe: How do bags form under your eyes? –Sophia Ivy, 7, New Providence, NJ

Dear Sophia Ivy,

If you’ve ever stayed up late and woke up really early, you may have noticed a little puffiness or swelling under your eyes.

When I asked my friend Devon Hansen about the answer to your question, she said that we first have to know a bit about how sleep works.

Hansen is a researcher at Washington State University and is very curious about sleep. She told me that the main way our sleep is regulated is through something called the circadian rhythm. You can think of it kind of like a 24-hour clock that helps run all the systems in your body, including sleep.

This system is actually controlled by light. Our ability to sense light is part of the reason why humans are awake and alert during the day. And when it’s dark out, we go to sleep.

It turns out that all the organs in our bodies are actually regulated by this circadian rhythm. That includes the biggest organ of them all: the skin.

Some scientists who have studied sleep have found that if you sleep poorly, your skin is not able to function as well. That is, it’s harder for your body to recover from being exposed to the outside environment, regulate your temperature, and stay hydrated.

While we don’t know all the details when it comes to exactly how these bags form the way they do, it’s likely that sleeping poorly has the ability to change the way your skin looks. That may include those bags, or even dark circles that form underneath the eyes.

You might even feel a little heaviness around your eyes when you are really tired. It’s kind of like how the rest of the muscles in your body get tired after you use them a lot.

It’s important to get a good night’s rest to make sure all your organs can stay healthy. Kids who are about five to ten years old usually need about 10 to 11 hours of sleep. And like grown-ups, 10 to 17-year-olds need about eight to nine-and-a-half hours a night.

While sleep is one of the main reasons we see bags forming under people’s eyes, there are also some other reasons. It might be partly genetic or your skin tone might just make them more obvious. We also see people get bags under their eyes when they have allergies or as they start to age.

As the body ages, the tissues around the eyes sometimes start to get a little weaker. The skin under our eyes is pretty thin and the blood vessels can sometimes stand out, making the bags a bit darker that they used to be.

So, a bit of puffiness under the eyes could be a sign that you are maybe a bit wiser than you once were—or that maybe you just need a little cat nap.

Dr. Universe

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Ask Dr. Universe – Shooting Stars

Dr. Universe: What are shooting stars made of? – Erin, 11, Arkansas

Dear Erin,

If you are anything like me, you probably like watching for shooting stars in the night sky. A shooting star, or a meteor, is usually a small rock that falls into Earth’s atmosphere.

When I went to visit my friend Michael Allen, a senior instructor of astronomy and physics at Washington State University, he told me a lot of shooting stars are no bigger than a pencil eraser.

“The earth is going to pass a random pebble once in a while and that will make a streak in the sky,” he said.

You might be wondering how such a small rock can create such a bright streak of light. If you’ve ever rubbed your hands together, you may know that friction is what helps them warm up.

When a small rock is falling into Earth’s atmosphere, it falls super-fast. Depending on the meteor, it can travel anywhere from 36,000 feet to 236,220 feet in a single second. As it falls, there is a lot of friction between the air and the rock. With all that friction, the rock starts to get really hot.

It is this friction that will help melt part of the rock. If the rock is small enough, it will evaporate, leaving behind a trail of hot gasses—and that’s the shooting star that you see streaking across the night sky.

Every now and then, we can see lots of shooting stars in the sky at the same time. When we see a meteor shower, we are seeing the little bits of a comet that has worked its way through the solar system. These meteor showers happen about a dozen times over the year and most last just a couple of hours.

When the icy comet intersects with Earth’s orbit, it gets heated up by the sun, and can break up into lots of smaller pieces of rock that can fall into Earth’s atmosphere. Meteors are rich in glassy or sandy materials, like quartz.

If a rock makes it from outer space to the surface of earth, we call it a meteorite. Allen also told me it’s really hard to know just by looking at a rock if it is from Earth or if it is something extraterrestrial.

If we really wanted to find out if a rock was a meteorite, we would need to look very closely at its atoms and its structure in a lab.

When we take a look at what makes up objects in space, we can learn quite a lot. By the way, unlike meteors, which are a solid, actual stars are really big exploding balls of gas. They are mostly made up of gases called hydrogen and helium.

The next time you look up to the vast night sky, remember that even the tiniest specks of dust and rock can light up the darkness—and that interstellar dust is falling around us all the time.

Dr. Universe

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Ask Dr. Universe – Sneezing

Dr. Universe: Why do we sneeze? -Nyuma, 10, North Carolina

Dear Nyuma,

Imagine you are home sick from school or are just playing outside when all of a sudden—ah-ah-ah-choo! It might seem like that sneeze came out of nowhere, but a lot of things went on in the brain and body to make it happen.

That’s what I found out from my friend Hans Haverkamp, a scientist at Washington State University who is really curious about the human body and how it works.

Your body’s muscles tense up and contract, making a sneeze “seriously explosive,” said Haverkamp. “Bam! Air comes flying out of your mouth, along with a bunch of germs.”

A sneeze, or a sternutation (stir-new-tay-shun), is a kind of reflex that helps protect you from things like dust, pollen, or chemicals in irritating odors. There are lots of different kinds of reflexes. If you’ve ever had a doctor tap your knee with a tiny rubber hammer, you may have felt the knee-jerk reflex before. A hiccup is another kind of reflex.

These are involuntary responses—you don’t even have to really think about it. The brain and body automatically take care of it for you.

In your body there are billions of nerve cells that help you feel and sense the world. They help with smell, sight, touch, taste, and hearing. When nerve cells in your nose sense that there is something in the nasal passageway that isn’t supposed to be there, they help send a signal to your brain. When the signal reaches your brain, it creates an automatic response and you start getting sneezy.

It takes muscles like your abdomen and your larynx, or voice box, to help push out a sneeze, too. The mucus that lines your nose and airways also helps grab onto some of those small invading particles. Sometimes a sneeze comes with a lot of snot, or mucous, too. It’s important to cover your sneeze to keep germs from flying out and landing on other people.

All kinds of animals sneeze, including, cats, dogs, and mice. Elephants sneeze out of their trunks, which is their nose. There are also animals like Galapagos marine iguanas that sneeze to get rid of sea salts that come from the process of digesting their food.

When humans sneeze, we will often hear other people say “bless you” or “gesundheit.” The phrase “gesundheit” is German and means “health.” “Bless you” comes from the sixth century when people had the plague and used this phrase in hopes people would get better soon.

According to the Guinness World Records, the longest sneezing fit, or most sneezes in a row, went to a woman in the United Kingdom. She sneezed about a million times in the first year and had her first day without a sneeze after 977 days. That must have been a lot of tissues.

But usually a sneeze is a sign that you have a cold or allergy and that your body is working hard to help you stay healthy.

Dr. Universe

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