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What does a planet have inside?

Dear Dr. Universe: What do planets have inside? -Rhianna, 10, Calif.

Dear Rhianna,

Each planet is a little different on the inside. And what’s inside a planet can shape what’s on the outside, too. That’s what I found out from my friend Steve Reidel, a geologist at Washington State University.

“Well, there’s the rocky planets,” he said. “Then there are the big, gas giants.”

Rocky planets, like Earth, are wrapped in a thick crust. Beneath Earth’s crust is the mantle. The mantle is quite solid, but it actually behaves more like a fluid. It flows and deforms. It’s similar to Silly Putty, but a really strong version of Silly Putty. It’s about 1,800 miles thick. It is also the main source of Earth’s volcanoes.

Even deeper in our planet is the core. It’s made up of metals, like nickel and iron. In fact, at the center of Earth there may be a ball of solid nickel and iron. It’s a solid because of the intense pressure there. But the outer part of the core is under less pressure, so it’s likely more fluid.

You may have heard that Earth is like one big magnet. It’s the reason why our compasses point north. Scientists think that as Earth’s fluid interior swirls around with the spin of Earth, it helps generate the planet’s magnetic field.

Earth’s magnetism is also part of the reason we have the Northern Lights. When particles from the sun strike particles in our atmosphere near the Earth’s magnetic field, it can create colorful displays.

While we can see some of the ways deep earth shapes our planet, we can’t actually look inside it. The deepest scientists have ever explored is about 5 miles into the Earth. Since we can’t slice up a planet, scientists use different measurements to figure out what’s going on.

One way they do this is to look at waves that earthquakes produce. Scientists can use seismometers, machines to measure the shaking of the ground, to help measure the waves. Some of these waves only move through solids, like the inner core. Others move through solids and liquids, like the outer core and mantle. They can use this information from the wave measurements to put together a better picture of the planet’s composition.

Other rocky planets—Mercury, Mars, and Venus—likely have similar interiors to Earth’s. It appears Mercury has the biggest core, at least compared to its size.

Then there are the giant gas planets: Neptune, Saturn, Jupiter and Uranus.

Air is one gas we all know. We breathe it. Planes zip through it. Each of these planets in the outer solar system is surrounded by different gases. We couldn’t stand on them.

If we did travel through the center of a gas giant, we would probably find something pretty familiar to our own rocky planet on the inside.

Your friend,
Dr. Universe

 

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Correction: An earlier version of this article described the mantle as big slush ball of hot liquid magma and minerals. This has been updated to a more accurate description of the mantle.

How does climate change affect the way we live?

Dear Dr. Universe: What exactly is climate change? How does it affect the way we live? –Pranav, 10, Melbourne, Fla.

Dear Pranav,

If you’re anything like me, one of the first things you’ll do in the morning is check the weather. Sometimes it’s rainy and I’ll put on my rubber boots. Other days it’s really sunny and I’ll grab my sunglasses. When we look at the patterns of these weather conditions over a long time—sometimes over hundreds of years—we can learn about a place’s climate.

My friend Marc Kramer is really curious about how the land, ocean, air, and living things are connected—especially when it comes to climate. Kramer is an environmental scientist at Washington State University who researches climate change.

When gases in the air trap heat, air temperatures can rise. These changes can affect the way we live in different ways, Kramer said.

Imagine for a moment, you are a fisherman. You have to fish to make a living and make sure people have a source of food. But as warmer air warms up the ocean, it makes living conditions hard for the fish. Fisherman can’t catch and sell seafood like they used to, which means less food for people to buy, too.

Meanwhile, lots of animals who live in polar regions see changes in their habitats. As air temperatures get warmer, polar ice caps and ice sheets melt. This not only impacts animals in these polar regions, but also humans who live on coasts. As ice near the poles melts, we see more flooding and people having to flee their homes.

As the air temperature rises, scientists note that snow melts earlier and there are more really hot summer days. Rain, snow and other kinds of precipitation start to fall in unusual patterns. Heat and drought make it harder for plants to grow. This means if you are a farmer, your plants struggle. Farmers feed a lot of us, so these changes affect people who like to eat dinner, too.

Kramer said the warming of our planet will produce many surprises in the weather and the ways we live. It’s hard to know exactly how, because it will vary with where you live.

Some of my friends at Washington State University are finding ways to help with these challenges. Scientists are looking at ways to grow food in severe heat or drought. Engineers are coming up with ways to power our planet with new fuels. They are working on all kinds of big questions about how climate change affects us. Sometimes that means investigating questions about water, health, and all kinds of living things.

Kramer told me about a few things we can do to help, too. One thing we can do is ask great questions like yours. We can take actions like using solar panels to power buildings. We can use electric cars. We can buy food that is produced close to our homes and that was grown in earth-friendly ways. We can also help others look for new ways to make changes, big or small, that can help this planet we call home.

Sincerely,
Dr. Universe

Why do we need stars? Can we make them on Earth?

Hello! My name is Daiwik and my question is “Why are stars in space? Why are they needed? Can they be made on Earth?” No one I know knows the answer to this. Can you find out for me? Thanks, Daiwik P.S. You’re awesome!! 

 

Dear Daiwik,

If you are anything like me, you like watching the night sky. The stars we see are a lot like our nearest star, the sun. They are just much farther away. That makes stars look like small twinkly things instead of a big, furious thing like our sun. » More …

Stars: What color are they?

Dear Dr. Universe: What color are our stars? -Mira, 8, Ontario 

Dear Mira,

Just the other night, I grabbed my binoculars and looked up to the starry sky. At first the stars looked white, but when I looked closer I noticed some appeared more blue and red. » More …

Volcanoes on other planets?

Dear Dr. Universe: I was just wondering if there are any volcanoes on any other planets? -Danny, 10, Kenmore, WA

 

Dear Danny,

The answer to your question takes us out into our solar system and deep below the surfaces of other moons and planets. » More …

Why does the Earth spin?

Dear Dr. Universe: Why does the Earth spin? -Morven, 8, Dundee, Scotland; Judith, 9, Sabah Malaysia; Mara, 11, USA

Dear Morven, Judith, and Mara:

No matter how still we stand, or if we’re in Scotland, Malaysia, or the United States, we are always spinning. Our Earth spins at a constant, very fast speed as we make a trip around the sun. » More …