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 …
Potential biosignature detected on Mars – What are these traces of life?
As the Perseverance rover traversed an ancient river valley in Mars’ Jezero Crater back in July 2024, it drilled into the surface and extracted a sample from of a unique, striped rock called Chevaya Falls. The rover’s instruments then analyzed the sample, which is called Sapphire Canyon, and surveyed the surrounding rock. When scientists started …
Can humans colonize Mars in the foreseeable future?
“Can we colonize Mars?” — Clara, age 9, Brookline, Massachusetts In all likelihood, the first Martian will be a person, and the red planet will be humanity’s first extraterrestrial colony. For now, two robots called the Curiosity Rover and the Perservance Rover – sent to Mars to find out if the planet can sustain small …
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, …
Does outer space end – or go on forever?
“What is beyond outer space?” — Siah, age 11, Fremont, California Right above you is the sky – or as scientists would call it, the atmosphere. It extends about 20 miles (32 kilometers) above the Earth. Floating around the atmosphere is a mixture of molecules – tiny bits of air so small you take in …
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 …
Nuclear rockets are twice as fast – but designing them isn’t easy
NASA plans to send crewed missions to Mars over the next decade – but the 140 million-mile (225 million-kilometer) journey to the red planet could take several months to years round trip. This relatively long transit time is a result of the use of traditional chemical rocket fuel. An alternative technology to the chemically propelled …
Why does time change when traveling close to the speed of light?
“Why does time change when traveling close to the speed of light?” — Timothy, age 11, Shoreview, Minnesota Imagine you’re in a car driving across the country watching the landscape. A tree in the distance gets closer to your car, passes right by you, then moves off again in the distance behind you. Of course, …
Humanity needs nuclear-powered rockets to explore Mars and beyond
With dreams of Mars on the minds of both NASA and Elon Musk, long-distance crewed missions through space are coming. But you might be surprised to learn that modern rockets don’t go all that much faster than the rockets of the past. There are a lot of reasons that a faster spaceship is a better …
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, …