Earth
Why does the Earth spin?
“Why does the Earth spin?” —Sara H., age 5, New Paltz, New York A globe was the first thing I ever bought with my own money. I was maybe 5 years old, and I was really excited to take it home. As I quickly discovered, you can spin it in the direction that the earth …
What is below Earth, since space is present in every direction?
“What is below Earth, since space is present in ever 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 …
Water recycling is key for ISS and Mars missions
When you’re on a camping trip, you might have to pack your own food and maybe something to filter or treat water that you find. But imagine your campsite is in space, where there’s no water, and packing jugs of water would take up room when every inch of cargo space counts. That’s a key …
How does the International Space Station stay in low Earth orbit?
“How is the International Space Station able to orbit without burning up?” — Mateo, age 8, New York, New York Flying through Earth’s orbit are thousands of satellites and two operational space stations, including the International Space Station, which weighs as much as 77 elephants. The International Space Station, or ISS, hosts scientists and researchers …
Why does a rocket have to go 25,020 mph to escape Earth?
“Why does a rocket have to go 25,020 mph (about 40,000 kilometers per hour) to escape Earth?” — Bo H., age 10, Durham, New Hampshire There’s a reason why a rocket has to go so fast to escape Earth. It’s about gravity – something all of us experience every moment of every day. Gravity is …
How was the Earth built?
“How was the Earth built?” — Noah, age 5, Florida It isn’t easy to figure out how the Earth was built, because it happened 4½ billion years ago, and no one was there to watch. So scientists have had to look at what the Earth looks like now and at all of the other planets, …
Why does everything look flat even though the Earth is round?
“Why does everything look flat even though the Earth is round?” — Zayden, age 11, Corona, California Ever since the ancient Greeks first made observations of the circular Moon and the skies, scientists have known that the Earth is a sphere. We’ve all seen beautiful images of the Earth from space, some photographed by astronauts …
Why on Earth is the planet’s day getting shorter?
Earth completed a rotation 1.33 milliseconds earlier than usual on Tuesday, August 5. That makes it one of the shortest days of 2025 at 86,399.99867 seconds long. How that happens, and how we can even measure it with such precision, might make your head spin faster too. On average, Earth physically rotates in 23 hours, …
Will the Earth last forever?
“Will the Earth last forever?” — Solomon, age 5, California Everything that has a beginning has an end. But the Earth will last for a very long time, and its end will come billions of years after anyone who is alive here now is gone. Before we talk about the future of our planet, let’s …
How has the inside of the Earth stayed hot for billions of years?
“How does the inside of the Earth stay boiling hot for billions of years?” — Henry, age 11, Somerville, Massachusetts Our Earth is structured sort of like an onion – it’s one layer after another. Starting from the top down, there’s the crust, which includes the surface you walk on; then farther down, the mantle, …