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What causes the northern lights? Are there southern lights, too? – Sebastian, 10, Minnesota

Dear Sebastian,

For many people, seeing the northern lights is the ultimate bucket list item. Lately, experiencing them has gotten a whole lot easier.

I asked my friend Michael Allen about those dancing green and pink lights. He’s an astronomer at Washington State University.

He told me that, along with its light, the sun emits charged particles—mostly protons and electrons. Those particles freely stream into space. Then, some of them bump into Earth’s magnetic field.

Earth has a magnetic field because there’s molten iron in its core. As the liquid metal moves and flows, it makes a giant magnet. The magnet is strongest near Earth’s poles. It makes loops of magnetic energy around the planet that reach out into space.

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Does the sun orbit anything? – Kingston, 11, Illinois

Dear Kingston,

When we think about orbits, we usually picture the Earth zooming around the sun. But does the sun just sit there? Or is it on its own journey?

I asked my friend Guy Worthey. He’s a space scientist at Washington State University.

He told me that an orbit happens because the gravity from something big pulls on a moving object. The sun has lots of gravity because it’s ginormous compared to Earth. So, that gravity pulls on the Earth and holds us in orbit.

But our sun isn’t the only star. It’s one of many, many stars in the Milky … » More …

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How does sunscreen work? – Seth, 6, Virginia

Dear Seth,

Since I’m a fluffy cat, my fur protects me from the sun. But my hairless cat and human friends use sunscreen when they go outside.

I asked my friend Michael Smerdon how it works. He’s a biochemist at Washington State University.

He told me that the sun puts out different kinds of light. Some light is visible to humans. Some is invisible—like UV light.

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Why is the sun so hot? – Ziyonna, 11, Indiana

Dear Ziyonna,

What happens if you do a big jump? Your body goes up into the air. But then it comes back down again. The reason you don’t just keep going up, up, up is because the force of gravity pushes your body and the Earth together.

It turns out gravity is a big reason the sun is so hot. That’s what my friend Michael Allen told me. He’s an astronomer at Washington State University.

He said that, at first, the universe was like a thick soup of gas and dust. Then, gravity pushed some of the gas and dust together. That’s how stars … » More …

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Why do we need the sun? – Samai, 9, Ohio

Dear Samai ,

Right now, the sun is shining through my window. It feels warm on my muzzle.

I talked about the sun with Guy Worthey. He’s a professor of astronomy and physics at Washington State University.

He told me that our lives depend on the sun.

“The sun keeps you warm and powers everything,” Worthey said. “Without it, Earth would be a frozen nightmare.”

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Why do we have to go to sleep at night, but the other side of the world is having morning? – Braelyn, 12, Ohio

Dear Braelyn,

If I drew a straight line through the Earth to the opposite side of the planet from me, I’d hit a place called Port-aux-Français. That’s an island near Antarctica. Mostly scientists live there.

Right now, it’s 12 PM, or noon, on Friday for me. But those scientists are probably snoozing in their beds. For them, it’s after 12 AM, or midnight, on Saturday. They’re already living in my tomorrow. Weird!

I talked about why that is with my friend David Luftig. He’s a science librarian at Washington State University. Science librarians are experts in two things: science and helping people find information for research and learning.

He told me it’s all because of Earth’s rotation. As the Earth rotates, or spins, the sun shines on one part of the Earth at a time.

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Hello Dr. Universe: I was wondering, how does an eclipse happen? - Susan, 13, San Francisco, CA

Dear Susan,

It just so happens the Great American Eclipse is coming up on Aug. 21, 2017. This solar eclipse will be the only one visible from across the lower 48 states in nearly a hundred years. When it happens, parts of the country will experience darkness for a couple minutes during the day.

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