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.

Are there thunderstorms on Mars? – Cade, age 7, Houston, Texas

Mars is a very dry planet with very little water in its atmosphere and hardly any clouds, so you might not expect it to have storms. Yet, there is lightning and thunder on Mars – although not with rain, nor with the same gusto as weather on Earth.

More than 10 years ago, my planetary science colleagues and I found the first evidence for lightning strikes on Mars. In the following decade, other researchers have continued to study what lightning might be like on the red planet. In November 2025, a Mars rover first captured the spectacular sounds of lightning sparking on the Martian surface.

Lightning on Mars

On Earth, lightning is an electric discharge that begins inside big clouds.

But because Mars is so dry, it doesn’t have clouds of water – instead, it has clouds of dust. With little water to weigh down dirt on Mars, dust clouds can quickly grow into huge, windy dust storms a few times taller than Earth’s tallest thunderstorms.

When smaller dust particles and larger sand particles collide with each other while being whipped around by these storms, they pick up a static charge. Smaller dust particles take on a positive charge, while larger sand particles become negative. The smaller dust particles are lighter and will float higher, while the heavier sand tends to fall closer to the ground.

Because oppositely charged particles don’t like to be apart, eventually the energy building between the negative charges higher up in the dust storm and the positive charges closer to the ground becomes too great and is released as electricity – similar to lightning.

The air around the electricity rapidly warms up and expands – on Earth, this creates the shock waves that you hear as thunder.

Nobody has seen a flash of lightning on Mars, but we suspect it’s more like the glow from a neon light rather than a powerful lightning bolt. The atmosphere near the surface of Mars is about 100 times less dense than on Earth: It’s much more similar to the air inside neon lights.

Releasing radio waves

Besides shock waves and visible light, lightning also produces other types of waves that the human eye can’t see: X-ray and radio waves. The ground and the top of the atmosphere both conduct electricity well, so they guide these radio waves and cause them to produce signals with specific radio frequencies. It’s kind of like how you might tune into specific radio channels for news or music, but instead of different channels, scientists can identify the radio waves coming from lightning.

While nobody has ever seen visible light from Martian lightning, we have heard something similar to the radio waves created by lightning on Earth. That’s the noise that the Perseverance rover reported at the end of 2025. They sound like electric sparks do on Earth. The rover recorded these signals on a microphone as small, sandy tornadoes passed by.

Searching for Martian lightning

When my colleagues and I went hunting for lightning on Mars a decade ago, we knew the red planet emitted more radio waves during dust storm seasons. So, we searched for modest increases in radio signals from Mars using the large radio dishes that NASA uses to talk to its spacecraft. The dishes function like big ears that listen for faint radio signals from spacecraft far from Earth.

We spent from five to eight hours every day listening to Mars for three weeks. Eventually, we found the signals we were looking for: radio bursts with frequencies that matched up with the radio waves that lightning on Earth can create.

To find the particular source of these lightning-like signals, we searched for dust storms in pictures taken by spacecraft orbiting Mars. We matched a dust storm nearly 25 miles (40 kilometers) tall to the time when we’d heard the radio signals.

Learning about lightning on Mars helps scientists understand whether the planet could have once hosted extraterrestrial life. Lightning may have helped create life on Earth by converting molecules of nitrogen and carbon dioxide in the atmosphere into amino acids. Amino acids make up proteins, tens of thousands of which are found in a human body.

So, Mars does have storms, but they’re far drier and dustier than the thunderstorms on Earth. Scientists are continually studying lightning on Mars to better understand the geology of the red planet and its potential to host living organisms.

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.

Nilton O. Rennó, Professor of Climate and Space Sciences Engineering, University of Michigan

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.

Why does orange juice taste bad after you brush your teeth? – Seth G., age 10, Bloomington, Indiana

It’s a mistake you hopefully only make once. In your morning rush to get ready, you brush your teeth before you head to the kitchen and down a big glass of orange juice. Yuck!

What makes your clean, minty mouth taste so gross when it meets OJ?

The short answer is that toothpaste contains a detergent that dissolves fat. And since your taste buds are partly made of fat, they are disrupted whenever you brush your teeth.

Before you decide you need to stop brushing your teeth to save your taste buds, know that this disruption is temporary, lasting only a few minutes. Brushing with toothpaste is still important for your health.

But how does this change in taste happen? And how are the taste receptors that are all over the surface of your tongue supposed to work?

I’m a psychologist, and I’ve spent more than 40 years researching the science of how people experience taste and flavor.

Let’s look at the science behind this phenomenon:

A bittersweet symphony

Thanks to evolution, your brain is wired to make you love the sweet sugars your body and brain need for fuel and hate the bitter poisons than could kill you. So your receptors for these two particular tastes are vital to your survival.

All of the cells in your body are held together by an outer layer, known as the membrane, that is made up of fats called lipids. And in sweet or bitter taste receptor cells, the cell membranes also contain a special molecule called a G protein-coupled receptor, or GPCR.

Some GPCRs are designed to detect sweet tastes. They tune out all compounds that aren’t sweet and respond only to the sugars your body can use. Others detect bitter tastes, tuning in to the large number of compounds in nature that are poisonous. They act as a built-in alarm system.

Salty chips and sour candies

Your perception of saltiness and sourness happens a little differently. These tastes are detected when positively charged ions called cations pass through tiny openings in the cell membrane of your salty and sour receptors.

In the case of saltiness, the cation is the positively charged sodium found in sodium chloride – common table salt.

For acidic, or sour, tastes, the cation is a positively charged hydrogen ion. While different types of acids may contain different chemical compounds, they all contain the hydrogen cation.

When you eat potato chips, the positively charged sodium cations from the salt pass through special openings in a receptor’s membrane, producing the salty taste. Similarly, the hydrogen cations in your favorite sour candy slip through other special openings in your sour receptor’s membrane and send a “sour” signal to your brain.

Toothpaste and OJ

The orange juice that many people like to drink with breakfast is naturally high in sugar. But it also contains citric acid, with its hydrogen cations. As a result, it’s a delicious combination of both sweet and a little sour.

But if you brush your teeth before breakfast, your OJ tastes terrible. What’s changed?

It’s not just that minty tastes clash with sweet ones. Toothpaste contains the detergent sodium lauryl sulfate, which helps remove dental plaque from your teeth. Plaque is the sticky film of germs that can cause cavities and make your breath smell bad.

If you ever do the dishes, you’ve probably seen what happens when you squirt detergent into a sink full of greasy water: The detergent breaks up the greasy fat, making it easy to wipe it off the dishes and rinse them clean.

But there’s another type of fat in your mouth that the detergent in toothpaste disrupts – the lipids in the cell membranes of your taste receptors. Brushing your teeth breaks up that layer of lipids, temporarily changing how you perceive taste.

Testing it out

Back in 1980, I conducted a study with a couple of my colleagues who were studying chemistry. We wanted to know how the tongue responds to sweet, bitter, salty and sour after being exposed to sodium lauryl sulfate, the detergent in toothpaste.

We conducted an experiment with seven student volunteers at Yale. They tasted very high concentrations of sweet sucrose, sour citric acid, salt and bitter quinine, both before and after holding a solution (0.05%) of sodium lauryl sulfate in their mouths for one minute.

You could conduct your own version of this experiment with something sweet like sugar, a little table salt, orange juice and tonic water. Taste them before you brush your teeth and then after, and see what happens!

We found that the intensity of the tastes of sucrose, salt and quinine were reduced by a small amount, but the most important change was that a bitter taste was added to the sour taste of citric acid.

This is why, instead of tasting sweet with a bit of nice tanginess, your OJ tastes bitter after you brush your teeth.

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.

Linda Bartoshuk, Research Professor of Psychology, George Washington University

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.

What is below Earth, since space is present in every direction? – Purvi, age 17, India

If you’ve seen illustrations or models of the solar system, maybe you noticed that all the planets orbit the Sun in more or less the same plane, traveling in the same direction.

But what is above and below that plane? And why are the planets’ orbits aligned like this, in a flat pancake, rather than each one traveling in a completely different plane?

I’m a planetary scientist who works with robotic spacecraft, such as rovers and orbiters. When my colleagues and I send them out to explore our solar system, it’s important for us to understand the 3D map of our space neighborhood.

Which way is ‘down’?

Earth’s gravity has a lot to do with what people think is up and what is down. Things fall down toward the ground, but that direction depends on where you are.

Imagine you’re standing somewhere in North America and point downward. If you extend a line from your fingertip all the way through the Earth, that line would point in the direction of “up” to someone on a boat in the southern Indian Ocean.

In the bigger picture, “down” could be defined as being below the plane of the solar system, which is known as the ecliptic. By convention, we say that above the plane is where the planets are seen to orbit counterclockwise around the Sun, and from below they are seen to orbit clockwise.

Even more flavors of ‘down’

Is there anything special about the direction of down relative to the ecliptic? To answer that, we need to zoom out even farther. Our solar system is centered on the Sun, which is just one of about 100 billion stars in our galaxy, the Milky Way.

Each of these stars, and their associated planets, are all orbiting around the center of the Milky Way, just like the planets orbit their stars, but on a much longer time scale. And just as the planets in our solar system are not in random orbits, stars in the Milky Way orbit the center of the galaxy close to a plane, which is called the galactic plane.

This plane is not oriented the same way as our solar system’s ecliptic. In fact, the angle between the two planes is about 60 degrees.

Going another step back, the Milky Way is part of a cluster of galaxies known the the Local Group, and – you can see where this is going – these galaxies mostly fall within another plane, called the supergalactic plane. The supergalactic plane is almost perpendicular to the galactic plane, with an angle between the two planes of about 84.5 degrees.

How these bodies end up traveling paths that are close to the same plane has to do with how they formed in the first place.

Collapse of the solar nebula

The material that would ultimately compose the Sun and the planets of the solar system started out as a diffuse and very extensive cloud of gas and dust called the solar nebula. Every particle within the solar nebula had a tiny amount of mass. Because any mass exerts gravitational force, these particles were attracted to each other, though only very weakly.

The particles in the solar nebula started out moving very slowly. But over a long time, the mutual attraction these particles felt thanks to gravity caused the cloud to start to draw inward on itself, shrinking.

There would have also been some very slight overall rotation to the solar nebula, maybe thanks to the gravitational tug of a passing star. As the cloud collapsed, this rotation would have increased in speed, just like a spinning figure skater spins faster and faster as they draw their arms in toward their body.

As the cloud continued shrinking, the individual particles grew closer to each other and had more and more interactions affecting their motion, both because of gravity and collisions between them. These interactions caused individual particles in orbits that were tilted far from the direction of the overall rotation of the cloud to reorient their orbits.

For example, if a particle coming down through the orbital plane slammed into a particle coming up through that plane, the interaction would tend to cancel out that vertical motion and reorient their orbits into the plane.

Eventually, what was once an amorphous cloud of particles collapsed into a disc shape. Then particles in similar orbits started clumping together, eventually forming the Sun and all the planets that orbit it today.

On much bigger scales, similar sorts of interactions are probably what ended up confining most of the stars that make up the Milky Way into the galactic plane, and most of the galaxies that make up the Local Group into the supergalactic plane.

The orientations of the ecliptic, galactic and supergalactic planes all go back to the initial random rotation direction of the clouds they formed from.

So what’s below the Earth?

So there’s not really anything special about the direction we define as “down” relative to the Earth, other than the fact that there’s not much orbiting the Sun in that direction.

If you go far enough in that direction, you’ll eventually find other stars with their own planetary systems orbiting in completely different orientations. And if you go even farther, you might encounter other galaxies with their own planes of rotation.

This question highlights one of my favorite aspects of astronomy: It puts everything in perspective. If you asked a hundred people on your street, “Which way is down?” every one of them would point in the same direction. But imagine you asked that question of people all over the Earth, or of intelligent life forms in other planetary systems or even other galaxies. They’d all point in different directions.

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.

Jeff Moersch, Professor of Earth, Environmental, and Planetary Sciences, University of Tennessee

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

Who invented art? – Grace, aged nine, Belfast, UK

Before we can answer this question, we need to think about another one: “what is art?” Art is something people make to share ideas or feelings. It can make others think or feel something too. Art can be many things including music, stories, paintings or drawings.

Cave paintings are often called the first art ever made. However, it’s possible the people who created the paintings thought of them as mysterious and powerful, quite different from art as we think of it today.

So who made them, why did they make them, and where can we find them? In a cave called Chauvet in southern France, archaeologists found drawings of animals such as woolly rhinos and mammoths that died out over 10,000 years ago. The people who made the drawings used black charcoal and red ochre – a colour made from crushed-up rocks that were chewed and spat into the artist’s hand, then pressed against the cave walls. Similar cave paintings have been found in Australia, India and Somaliland.

Curious Kids is a series by The Conversation that gives children the chance to have their questions about the world answered by experts. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.com and make sure you include the asker’s first name, age and town or city. We won’t be able to answer every question, but we’ll do our very best.

Some people think the cave paintings weren’t just for fun or decoration. They believe the drawings were supposed to be a kind of “magic”. By drawing animals like deer or bison, they argue, the person who made the picture (maybe a hunter) thought it would give them magical power over the animal they were hoping to catch.

Early thinking about art

A long time ago, a Greek thinker named Aristotle said that the point of art was to imitate the world around us. For him, art wasn’t just painting or drawing – it also included acting and even giving speeches. Because artists used their hands to make things, people thought of them like workers or craftspeople – similar to cooks, hairdressers, or blacksmiths.

In 13th- and 14th-century Europe, art was mostly connected to the church, and was made to help people feel closer to God. Artists were part of groups called guilds, based on the kind of work they did, and people saw them more as skilled workers than as creative individuals.

It wasn’t until the 15th and 16th centuries, known as the Renaissance in Europe, that artists began to see themselves as creators, not just craftsmen. A big change happened in 1436 when a man named Leon Battista Alberti wrote a famous book called On Painting, which claimed that art was just as important as poetry and science. His ideas had a huge effect in the city of Florence in Italy, where three very famous artists worked: Leonardo da Vinci, Michelangelo and Raphael.

People started to think more about artists as special individuals, which was shown in another important book, Lives of the Artists, written by Giorgio Vasari in 1550.

Art began to be divided into two groups. The first was called the “fine arts”, which included painting, sculpture and drawing. These were seen as more important because they expressed big ideas and emotions. The second group was called the “decorative arts”, like glass-making, wood-carving and book decorations. These were thought to be less important because they were more about looking nice or being useful.

Changing how people think about art

In the late 19th century, people started to like the decorative arts more, because artists wanted to focus on handmade things instead of factory-made items. But painting was still seen as the most important kind of art. Then, in 1914, a French artist named Marcel Duchamp changed how people thought about art.

He started using everyday objects and turning them into art just by choosing them and signing them. He called these “readymades”. His most famous one was called Fountain – it was actually a type of toilet (a urinal) that he signed with a fake name, “R. Mutt”, and tried to put in an art show in New York in 1917. Duchamp said that picking an ordinary object and calling it art was enough to make it art, because the artist made the choice.

Duchamp helped change art by showing that it isn’t just about painting or making statues – it’s also about ideas.

Today, many artists use their work to talk about important issues and to make people think. In this way, they are no different from the artists of the past – such as the first cave dwellers who exerted power over their prey, or Duchamp, who challenged the very meaning of art.

And so the answer to the question “who invented art?” is quite simple. Humankind invented art – from the moment we were able to trace a pattern in the sand, or transfer a simple idea to the wall of a cave.

Frances Fowle, Personal Chair of Nineteenth-Century Art, History of Art, University of Edinburgh

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.

Are people on the South Pole walking upside down from the rest of the world? – Ralph P., U.S.

When I was standing at the South Pole, I felt the same way I feel anywhere on Earth because my feet were still on the ground and the sky was still overhead.

I’m an astrophysicist from Wisconsin who lived at the South Pole for seven weeks from December 2024 to January 2025 to work on an array of detectors looking for extremely high energy particles from outer space.

I didn’t feel upside down, but there were some differences that still made the South Pole feel flipped over from what I was used to.

As someone who loves looking for the Moon, I noticed that the face of the man on the Moon was flipped over, like he went from 🙂 to 🙃. All the craters that I was used to seeing on the top of the Moon from Wisconsin were now on the bottom – because I was looking at the Moon from the Southern Hemisphere instead of the Northern Hemisphere.

After noticing this difference, I remembered something similar in the night skies of New Zealand, a country near Antarctica where my fellow travelers and I got our big red coats that kept us warm at the South Pole. I had looked for Orion, a constellation that in the Northern Hemisphere is viewed as a hunter holding a bow and drawing an arrow from his quiver. In the night sky of New Zealand, Orion looked like he was doing a handstand.

Everything in the sky felt upside down and opposite, compared with what I was used to. A person who lives in the Southern Hemisphere might feel the same about visiting the Arctic or the North Pole.

An out-of-this-world perspective

To understand what’s happening, and why things are really different but also feel very much the same, it might be useful to back up a bit from Earth’s surface. Like into outer space. On space missions to the Moon, astronauts could see one side of the Earth’s sphere at once.

If they had superhero vision, an astronaut would see the people at the South Pole and North Pole standing upside down from each other. And a person at the equator would look like they were sticking straight out the side of the planet. In fact, even though they might be standing on the equator, people in Colombia and Indonesia would also look like they were upside down from each other, because they would be sticking out from opposite sides of the Earth.

Of course, if you asked each person, they would say, “My feet are on the ground, and the sky is up.”

That’s because Earth is essentially a really big ball whose gravitational pull on every one of us points to the center of the planet. The direction that Earth pulls us in is what people call “down” all over the planet. Think about holding a baseball between your pointer fingers. From the perspective of your fingertips on the ball’s surface, both are pointing “down.” But from the perspective of a friend nearby, your fingers are pointing in different directions – though always toward the center of the ball.

These relationships between people on the Earth’s surface are good for a little bit of fun, though. While I was at the South Pole, I pointed my body in the same direction as my friends in Wisconsin – by doing a handstand. But if you look at the picture the other way around, it looks like I’m holding up the entire planet, like Superman.

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.

Abigail Bishop, Ph.D. Student in Physics, University of Wisconsin-Madison

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