Earth is like a giant bowl of piping hot soup. Sure, it's round instead of bowl-shaped. And if you tried to eat it, you would almost certainly break a tooth on the outside or burn your tongue on the inside. Not to mention the fact that I don't think there's a stomach or a spoon big enough to eat the earth. But still, the stuff earth is made of acts a lot like a cooled bowl of soup. So let's take our imaginary, galactic-sized soup spoon and break the soup skin. Let's dig into the earth, shall we? And see what's happening down there.
If you leave a bowl of soup to cool, after a while you will find a layer of soup skin. This is the gross stuff that most people spoon off of their soup before they start eating. But we should be happy about our earth's cold skin. Earth's crust
is the cool outer layer that we all stand on. Just like in a bowl of soup, it has cooled down and grown harder. It's thinner than the other layers beneath, but thick enough to hold us up and to keep our shoes from catching on fire. Oh, and just in case this gives you any ideas . . . don't try to stand on your soup skin. You will break through and get soupy shoes.
Earth crust, pie crust. I think pie crust tastes better.
Let's peel back the soup skin . . . I mean crust. Steam rises into the air! The layer right under the soup skin is very hot. The same goes for the earth's next layer. The mantle
is the layer beneath the earth's crust that's part liquid, part solid, very hot and always moving. Heat rises, so the lava beneath the crust moves toward the earth like a soup bubble trying to rise up through the soup skin. The earth's crust is too thick though, so the lava cools near the skin and then falls back down again. It does this over and over in a circle. This is what moves our land around. Unlike the mantle, your soup doesn't get hot enough to move the soup skin around. But soup has something magma does not: it's yummy.
Sometimes lava pops out through the earth's crust. It's what's not for dinner.
If we go a bit deeper, we are going to get really hot. No amount of blowing or tossing in ice cubes will cool it down. The outer core
is made of metals that are so hot that they have melted and are moving around. Think of that! It would melt your bike, a car, the change in your pocket, even a building. The outer core warms the mantle, which then moves the crust around. The next time you burn your tongue on soup that's too hot, just be happy that it was not heated in the outer core.
Liquid gold metal. Here's something that will melt your socks off.
And now we come to the middle of the earth and the bottom of our soup bowl. This layer is made of the same stuff the outer core is, but with one big difference. The inner core
is made of melted metals that have so much stuff pushing down on them that they are solid. That's right, sitting in the middle of our earth is a ball of solid metal. Like the bottom of the soup bowl, this is the hottest layer of the earth. Unlike the soup at the bottom of the bowl though, this layer is as hot as the sun.
Just like a bowl of soup, the earth has different layers. You have the crust on top and then the hotter layers below. Each one is hotter than the last. Because hot things are always trying to move up, this heat keeps our land moving. Now dig in to this soup before it cools too much and all you have is gross soup skin. Slurp. Ahh. Just like Earth. Not too hot on top. Not too cold below.References:
"Science for Kids: Composition of
the Earth." Ducksters. Technological Solutions, Inc.
Today. "How Was the Earth Formed?" Universe
"Japanese Restaurant Serves Meal of Dirt--for $110" Time,