This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

Why do you have to wear a helmet in space? - Leonardo, age 3, Curtin, ACT.

Hi there Leonardo. What a great question.

There is an easy answer: it’s just that out there in space there is no air. We need air to breath to keep us alive.

Here on our planet, the gravity holds the air down close to Earth so we can all share it. Gravity is the force that stops everything on Earth from floating away. The bigger a planet is, the stronger its gravity.

But up there in space all the air has been sucked up closer to big planets like Earth because of their gravity.

It’s also really cold in space.

That’s the short answer. If you want the long answer, ask your parents to read you the story below.

Not so long ago, in a galaxy not too far away…

Once upon a time, there was a boy named Leonardo. He won a competition to go to space!

When he got to space, he put on his space suit and helmet and went outside to float around for a little while. He was tied to his spaceship, so he would not float away.

Suddenly, he saw an alien on a nearby floating rock. The alien was inside a big glass dome, waving at Leonardo.

“Hi there Earth boy. My name is Ein,” the alien said. “Welcome to space. What’s your name?”

“I’m Leonardo. I’m the very first kid to visit space. I won a space competition,” he said.

“Wow!” said the alien. “Why don’t you float over to my rock? Just push off gently, one finger only.”

Leonardo pushed off from his spaceship with one finger. That was all it took to get him heading over toward the alien’s rock. It was so easy to float - so slow, so steady, so gentle!

Stopping the air whooshing out

As he drifted over, he asked the alien: “Ein, why do you live in a big glass dome?”

“Same reason you are wearing a space suit and helmet,” said Ein. “You need to keep the air in. If you took your helmet off, all the air would whoosh out and you wouldn’t be able to breathe.”

Leonardo was still drifting closer.

“I could never understand that,” he said. “When I open my front door at home the air doesn’t whoosh out. What is so different about space?”

“Well, first, do you know what air is made of?” said Ein.

“Yes, it’s made of atoms. They are teeny weeny things, too small to see. Everything is made of atoms,” said Leonardo. He was a very smart boy.

“You know, the atoms in the air you are breathing are moving at the speed of a jet plane,” said Ein. “They are bouncing all around inside your helmet, and are bouncing off your skin right now.”

“That’s crazy. They would be hurting my skin!” said Leonardo.

“No. There are so many trillions of them. They are super-tiny. They bounce off,” said Ein.

“But if you took off your helmet, the air atoms would have nothing to stop them. They would go shooting off at the speed of a jet plane.”

Air sticks close to planets

Leonardo was confused. “Then why doesn’t all the air shoot off Earth the same way?” he asked.

“The gravity of Earth holds it in,” explained Ein.

“A rocket - like the one that brought your spaceship to space - can go fast enough to escape Earth’s gravity. But atoms aren’t going that fast, so they stick close to Earth.”

Leonardo was nearly at Ein’s rock now. “So air sticks close to all the other big planets, because they have gravity?”

Ein smiled. “Yep,” she said. “It’s got a bit to do with how our universe was created when the Big Bang happened. But I’ll explain that after morning tea.”

A special air lock door on Ein’s dome opened, so Leonardo could come in without all of Ein’s air whooshing out.

Leonardo couldn’t wait to tell his Earth friends all about his new alien friend – and what he had learned about why an astronaut must always wear a helmet in space.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au
* Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or
* Tell us on Facebook

Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

David Blair, Emeritus Professor, ARC Centre of Excellence for Gravitational Wave Discovery, OzGrav, The University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

I lost my first tooth on Tuesday. I was fiddling with it while I was watching TV. I had a mouthful of blood! It soon stopped bleeding. When I looked at the bottom of my tooth the edge was very spiky! Can you tell me why? – Nicholas, age 6, North Sydney.

Thanks for the great question, Nicholas.

At around six months of age, babies usually start getting teeth. The first to appear are the thin front teeth, called incisors. New teeth keep erupting from the gums until around two or two-and-a-half years of age. The molars - the flat grinding teeth at the back of the mouth - come up last. In total, you end up with 20 baby teeth.

At around six years of age, the bottom incisors start to loosen. When adult teeth start to grow, they cause the roots of the baby teeth (which are hidden under the gum and hold the teeth to the jaw) to be “eaten away” to make space for the adult teeth working their way up into the mouth.

Soon the roots of the baby teeth are eaten away until they start to get wobbly. Soon it gets so wobbly it gets knocked out when you eat something or brush your teeth. Or you might twist it out while you’re watching TV, just like you did.

There often is some blood because the wobbly tooth is still attached to the gum, so that gets torn when the tooth is lost and it bleeds a little. There often seems to be more blood than there really is because it mixes with your spit.

The edges of your tooth were sharp because when the root of the baby tooth is being eaten away by the growing adult teeth, it tends to start from the middle of the root. Something like a rough shell edge is left when most of the root has been absorbed and the tooth is finally lost.

When you look at an X-ray, you can see that the baby teeth still have most of their roots, so they look very different to your fallen tooth. You can also see that the growing adult teeth don’t have complete roots - they still grow for a while after the tooth erupts into the mouth.

Some people lose teeth a bit earlier and some a bit later than the normal time, but this is usually OK. However, if your first set of teeth start to fall out before you turn five, then it is worth seeing a dentist who is good at treating kids.

Soon, Nicholas, you will start to get new teeth at the back of your mouth. They’re called the first permanent molars and there are four of them, one in each corner.

These teeth will erupt without a baby tooth falling out, as they are appearing in spots that are currently empty. After that happens, you will have 24 teeth, until you start losing more baby teeth when you are nine or 10.

Then you’ll get more molars at the back (these guys are called the second permanent molars) when you are around 12, and then third permanent molars when you are around 18 or so. These ones are often called wisdom teeth.

Baby teeth are really important. They allow you to chew food, have a nice smile, and help keep space for adult teeth. So it is good to avoid lots of sugar and brush your teeth twice a day with fluoridated toothpaste.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au
* Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or
* Tell us on Facebook

Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

David Manton, Professor of Paediatric Dentistry, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

How do glasses help you see? – Andy, age 5, Vincentia.

Hi Andy, and thank you for your question about glasses.

You’ve asked this at a very good time because more and more people are needing to wear glasses, including young children, and we don’t really know why.

Our eyes let us see because light enters each eye, and the eye then creates a message that goes to the brain.

The eyeball itself doesn’t actually “see” – the brain sees. The eyeballs just take pictures, like two little cameras. To see properly, each eyeball needs to send the light that enters it onto a very exact spot inside the eyeball, called the retina. If the light falls onto the wrong place, your vision will be blurry.

Many people don’t need glasses and can see just fine. This is because their eyeballs are focusing light properly onto the retina.

However, some people have eyeballs that are too long. They are called “shortsighted”. For these people, things far away, like street signs or the classroom blackboard, can look blurry.

Other people have eyeballs that are too short. They are called “farsighted” and things close to them, like a book or a mobile phone, can look blurry.

Both shortsighted and farsighted people need glasses to help them see clearly.

They work by helping the eyeball to focus light onto the correct place, the retina. Only then can the eye see clearly.

Maybe you have a grandma or grandpa who wears glasses whenever they are reading books or using their mobile phone. When people get older, they usually become a little bit farsighted because a part of their eye called the lens becomes stiff and doesn’t work properly.

More and more young people in the world are needing to wear glasses.

We’re not sure why, but some scientists think that children who spend too much time inside are more likely to need glasses. We don’t know if it’s because they aren’t getting enough sunlight or if they’re simply reading too much or playing too many video games when they get home.

Most children in China are shortsighted and need glasses to see things far away. The Chinese government is so worried about this that they are making sure all students spend some time outdoors instead of just being inside the classroom.

Glasses can cost lots of money, and children who need glasses but don’t wear them don’t do as well in school. Once you need glasses, you usually need them forever - your eyes won’t go back to normal on their own.

I hope that one day we can find out why people’s eyeballs become too long or too short and then we can stop people needing to wear glasses in the first place. Then people will never lose or forget their glasses ever again!

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:

* Email your question to curiouskids@theconversation.edu.au
* Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or
* Tell us on Facebook

Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

Jason Yosar, Associate Lecturer, School of Medicine, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky! You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.

Why do volcanoes erupt? - Nicholas, age 3 years and 11 months, Northmead, NSW.

The rock inside the planet we live on can melt to form molten rock called magma. This magma is lighter than the rocks around it and so it rises upwards. Where the magma eventually reaches the surface we get an eruption and volcanoes form.

The top part of the Earth is made up of a number of hard pieces called tectonic plates. Magma and volcanoes often form where the plates are pulled apart or pushed together but we also find some volcanoes in the middle of tectonic plates.

Volcanoes have many different shapes and sizes, some look like steep mountains (stratovolcanoes), others look like bumps (shield volcanoes) and some are flat with a hole (a crater or caldera) in the centre that is often filled with water.

The shape of the volcano and how explosively it erupts depend largely on how “sticky” and how “fizzy” (how much gas) the magma is that is erupted.

For example, if you try to blow bubbles in cooking oil though a straw, the bubbles can escape quite easily because the cooking oil is runny.

If you try to blow bubbles in jam or peanut butter you would find it very difficult because the jam and peanut butter are very sticky, they wouldn’t move much at all if you tried to pour them out of the jar.

It is the same with volcanoes. When magma rises towards the surface gas bubbles start to form. Whether or not they can escape as the magma is rising affects how explosive the eruption will be.

Where the magma is runny like cooking oil and doesn’t have much bubbly gas mixed in it, such as places like Hawaii, then we see lots of slow-moving lava flows and shield volcanoes. Lava is what we call magma when it reaches the surface.

Here are some pictures of a recent Hawaiian eruption:

However, where the magma is very sticky, like jam or peanut butter, and if it contains a lot of bubbly gas then the gas can get stuck and eruptions can be very powerful and explosive, like the recent eruptions at Fuego volcano in Guatemala.

Damage caused by eruptions

In explosive eruptions the frothy, bubbly magma can be ripped apart into tiny bits called volcanic ash. This is not ash like you get after a barbecue or fire, it does not crumble away in your fingers. It is very sharp and is dangerous to breathe in.

Some explosive volcanoes can send ash high up into the sky and it can travel around the world over different countries. If aeroplanes travel through an ash cloud from a volcano it can cause a lot of damage to the engine.

Other explosive eruptions create fast-moving, hot clouds of volcanic ash, gas and rocks that travel down the sides of the volcanoes and destroy pretty much everything in their path.

The benefits of volcanoes

Despite the great damage they can cause, volcanoes also help us to live. Volcanic ash provides food for the soil around volcanoes which helps us grow plants to eat. The heat from some volcanoes is used to make energy to power lights, fridges, televisions and computers in people’s houses.

You can find some more information about different types of volcanoes here and here.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au
* Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or
* Tell us on Facebook

Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

Heather Handley, Associate Professor in Volcanology and Geochemistry, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky! You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.

Hello, The Conversation. How was the ocean formed? Where did all of the water come from? – David, age 5, Brisbane.

On Earth there is more ocean than land. Of course, there is also a lot of water locked up as ice at the North and South Poles. Where all that water came from is a very good question. Scientists have been wondering about it for a long time. We are still not exactly sure but it is probably a combination of two places.

Let’s start with how the Earth and the other planets formed.

In the beginning, there was a huge cloud of dust and rocks in the Universe. Gravity caused the cloud to shrink and gradually the Sun and the planets formed.

The original dust and rocks included minerals that had water in them. The Earth, as it formed, became very hot. It melted and there were lots of volcanoes. The water in the rocks formed steam and came out of the volcanoes as giant clouds that cooled and rained. That is where some of the water came from.

Also, the original cloud of dust and rocks included a lot of rocks that were made of ice, like giant snowballs. There are still lots of them circling the Sun. We call them comets. There were billions of them when the planets were forming and many crashed to the ground and melted. That is where the rest of the water came from.

Now the question is, how did the water form in the Universe in the first place? That is another big question for another time, but the short answer is this: water is made of hydrogen and oxygen atoms. (Atoms are the tiny little building blocks of the Universe - even you and I are made of atoms).

The hydrogen atoms in water formed in the Big Bang that started the Universe. The oxygen atoms were made later in stars. They got together and water was formed.

So, our water is ancient and precious. Let’s look after it.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au
* Tell us on Twitter

Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

Malcolm Walter, Professor of Astrobiology, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

How hot does it get in the desert? – Henry, age 5, South Bend, Indiana

When you think of a desert, you probably imagine giant waves of sand dunes beneath a blazing Sun. You’d be picturing a hot desert, like the Sahara in Africa.

Some of the most scorching temperatures recorded on Earth have been in deserts. The hottest air temperature on the Earth’s surface was 134 degrees Fahrenheit (56.7 degrees Celsius) in Death Valley, California. The highest ground temperature was 177.4 F (80.8 C) in the Lute Desert in Iran.

For comparison, a very hot bath is around 110 F (43 C). So these temperatures are way beyond anything safe for your skin.

What makes some deserts so broiling hot, and why do they exist in the first place? It has to do with how Earth’s atmosphere moves around our planet and interacts with what’s on the ground.

What is a desert?

Climate scientists like me define a desert not by temperature but by how much precipitation it gets – any form of water falling from the sky, whether rain, snow or hail. If an area receives less than 10 inches (250 millimeters) of precipitation a year, it is officially a desert.

There’s nothing in this definition about being hot. In fact, there are cold deserts, too. The biggest desert on Earth is Antarctica, where the average winter temperature can be as low as -75 F (-60 C) in the interior highlands.

Antarctica counts as a desert because it rarely snows there. It’s covered by a large ice sheet that’s the result of tiny amounts of snow accumulating over tens of millions of years.

Where are they, and why?

The equator is an imaginary line wrapped around the middle of the Earth, separating it into two halves: the Northern and Southern hemispheres. Lines of latitude are imaginary rings parallel to the equator that further divide up the hemispheres. Latitude is measured in degrees, starting at 0 degrees at the equator up to 90 degrees at each pole.

If you look at a globe, you’ll notice an interesting pattern. Most of the world’s hot deserts – including the Sahara, the Arabian Desert and Australia’s Great Victoria Desert – are lined up within two horizontal belts around the Earth that lie at roughly 30 degrees north and 30 degrees south of the Equator.

These locations are not a coincidence. They’re related to how the atmosphere moves around Earth.

Globally, the equator gets the most direct sunlight, so the air near ground level there becomes warm and rises. At the poles, the air is very cold and sinks. This continuous rising and sinking motion creates a giant loop of moving air for each hemisphere, almost like a slow‑moving conveyor belt in the atmosphere.

Because the Earth spins, the giant moving air loop gets twisted and broken into three smaller loops for each hemisphere. As a result of this atmospheric motion, air generally rises at the equator and latitudes around 60 degrees and sinks at the poles and latitudes around 30 degrees.

When air rises, it expands and cools. As its temperature goes down, water vapor condenses to form precipitation. When air sinks, it compresses and warms up, causing water to evaporate and creating dry conditions.

That’s why deserts are found around 30 degrees and near the poles. Those are the places where atmospheric motion causes the air to sink – resulting in dry desert conditions.

Why does it get so hot?

The deserts near the 30 degrees latitude line can get incredibly hot for three reasons.

The first reason can be found in the clouds. In most parts of the world, moisture in the air forms clouds. On a cloudy day, you might notice that clouds block the Sun’s light, helping create cooler temperatures. Because desert air is extremely dry, it lacks this protective shield. With no clouds to provide shade, all of the Sun’s incoming solar energy reaches the Earth’s surface, heating the ground at full intensity.

Another reason behind these deserts’ high temperatures is what you find below your feet. At the beach, you might notice that the sand feels much warmer than the ocean on a hot day. That’s because of the difference in their specific heat, a term scientists use to describe how much energy something needs to change its temperature.

Water has a very high specific heat and therefore takes a lot of energy – and hence a long time – to warm up. Conversely, rocks and sand have low specific heats; they absorb the energy from the Sun and warm up very fast. For the same reason, they can’t hold onto that warmth when the Sun goes down. Once night falls, all that heat escapes right back into space. This is why a desert can go from roasting at noon to freezing at midnight.

A final reason those hot deserts stay hot has to do with the way water removes heat when it evaporates. In nondesert places, plants release water into the air, cooling the surrounding area. Scientists call this phenomenon evaporative cooling. It’s the reason you can feel cold when you get out of a pool even on a warm day.

In deserts, the ground is dry and there are very few plants, so almost no evaporative cooling happens. Without this natural cooling system, the Sun’s heat stays trapped at ground level, making the daytime desert feel scorching.

How global warming is changing the desert

Because our planet is warming up due to human activities such as burning fossil fuels – coal, oil and natural gas – and cutting down forests, deserts are experiencing some major shifts.

In many parts of the world, global warming makes deserts hotter, drier and dustier. It also makes them spread outward into places that used to have more plants. When regular land turns into a dry desert, it’s called desertification.

Climate change doesn’t affect every place the same way, though. In some desert regions, shifting wind patterns are actually bringing more rain than usual, leading to a partial greening of the desert. This has been observed in the Thar Desert in India and Pakistan, the southern fringe of the Sahara Desert and some deserts in northern and northwestern China. Such major shifts in desert conditions change the ecosystem, making it harder for native animals and plants, which are adapted to the desert environment, to survive.

Deserts are some of the most extreme, beautiful and finely balanced places on Earth. Understanding how the atmosphere and the land work together reveals how even the hottest places on our planet are connected to the rest of the world.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Shuang-Ye Wu, Professor of Geology and Environmental Geosciences, University of Dayton

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Nine-year-old Eva was watching an episode of the children’s show Horrible Histories about the stone age recently when a question popped into her head. The cave men were speaking a broken form of English, but Eva thought that didn’t sound right and she wondered: how was the first language formed?

She joined our host Eloise to get some answers from anthropologist April Nowell on The Conversation’s Curious Kids podcast.

In each episode of The Conversation’s Curious Kids, a child joins host Eloise to ask a top researcher their burning question.

To listen to season two, follow us wherever you get your podcasts, or listen on the Yoto Player via the Discover section on the Yoto interactive audio platform for kids.

You can also listen back to season one and read lots of answers to questions sent in by children around the world in our Curious Kids series.

Got a question? Pop it in an email, or record it and send us the audio to curiouskids@theconversation.com.

This season of The Conversation’s Curious Kids is supported by the University of Southampton in the UK, a world-leading research-intensive university with a global network of international students and campuses in Malaysia and Delhi.

Disclosure statement

April Nowell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Credits

This episode of The Conversation’s Curious Kids was hosted and mixed by Eloise Stevens. The producer was Katie Flood and the executive producer was Gemma Ware. Credits in this episode to Horrible Histories, Pysched for Nature and Wild Ambience.

Eloise Stevens, Host, The Conversation's Curious Kids podcast, The Conversation and Gemma Ware, Head of Audio, The Conversation UK, The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.