How Do Scientists Know What Is Inside Earth When Nobody Has Ever Dug That Deep?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. How do scientists know what is inside Earth when nobody has ever dug that deep?

The Big Idea

Nobody has ever dug anywhere near the center of Earth! The deepest hole ever drilled is only about 12 kilometers deep. So how do scientists know what is inside? They use clever clues.

Quake Waves

Step one: quake waves. When an earthquake happens, waves travel through the whole planet. Instruments called seismometers record them on the other side.

Bends and Speeds

Step two: bends and speeds. Waves bend, speed up, or slow down as they pass through different layers. That tells scientists where the layers begin and end.

A Liquid Layer

Step three: a liquid layer. Some waves cannot pass through liquid, which showed the outer core is melted metal. Meteorites and lab experiments add even more clues.

A Closer Look

Let's take a closer look! On top is the thin, rocky crust. Below it is the thick, hot mantle. Under that, the outer core is melted metal. In the middle sits a solid inner core.

Quick Facts

Quick facts! Earthquake waves work like an X-ray of the planet. It is a long way to the center, about 6,400 kilometers. We have drilled less than one percent of the way down. The inner core is solid, even though it is incredibly hot.

Think Like a Scientist

Now, think like a scientist! Ask a grown-up to hard-boil an egg, and let it cool. Spin it and a raw egg on a table, then stop each with a finger and let go. The raw egg keeps moving, because the liquid inside is still swirling. You can tell what is inside without cracking it. Wash your hands afterward!

Outro

Waves and clues show us what is inside Earth. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!