Summary
Introduction
How did the Moon get its craters? What about the craters on Earth? Why do they look the way they do? Find out in this fun science activity, as you make your own craters by dropping balls into a tray of flour.
Materials
- Large baking pan or shallow cardboard box
- Flour (enough to fill the pan)
- Cocoa powder (enough to create a thin layer on top of the flour)
- Sieve or sifter
- Balls of various sizes
- Optional: ruler and meter stick
Prep Work
Instructions
- Fill the baking pan with flour.
- Use the sieve to put a thin layer of cocoa powder on top of the flour.
- Try dropping a ball into the pan from about half a meter above it (optionally, use the meter stick so you can drop from a consistent height).
- Look at the resulting impact crater. What color is the surface immediately around the crater? How does that compare to the surface of the rest of the pan? How far did the flour and cocoa powder spread? Optionally, use the ruler to measure these distances.
- Try dropping the same ball from a different height. What does the resulting crater look like?
- Try dropping balls of different sizes from the same height, and examine the resulting craters.
- You can even try throwing a ball sideways so it hits the pan at an angle, instead of coming straight down. How is the resulting impact pattern different from when you dropped the balls straight down?
- If needed, smooth out the surface of the pan, and sift a fresh layer of cocoa powder on top.
Cleanup
What Happened?
You should have found that the bigger the ball, or the faster it was moving, the bigger the resulting crater would be. This is because larger, faster-moving balls have more kinetic energy than smaller, slower-moving balls. This energy is transferred to the flour and cocoa powder when the ball hits the ground, causing it to fly outward, creating the crater (and a mess!). You should also have seen that the impacts churned up the "soil," bringing some of the white flour to the surface near the impact site. While the pattern around the crater was probably symmetric if you dropped the ball straight down, sideways impacts would result in asymmetric patterns as more flour/cocoa powder were thrown in one direction than the other.
Digging Deeper
Craters are round, bowl-shaped depressions surrounded by a ring, like the one shown below. Impact craters are made when a meteorite crashes into a planet or moon (as opposed to volcanic craters, which are created when a volcano erupts). Just like in your science experiment, the size and shape of the crater depends on how big the meteorite was and how fast it was going when it hit the ground. A bigger, faster-moving meteorite will create a bigger crater, sometimes throwing material very far away from the impact site.
Some of the craters on the Moon are so big that you can see them with the naked eye! While Earth has over 100 known impact craters, not all of them are obvious. Unlike the Moon, Earth has an atmosphere with weather that causes erosion (wind and rain), along with animals and plants that can move soil and change landscapes over time. So, some craters on Earth's surface may be eroded or overgrown. Many meteoroids (they are called meteoroids while they are still in space, and meteorites once they hit the ground) also burn up in Earth's atmosphere, never reaching the ground at all.
Ask an Expert
For Further Exploration
- Scale this project up! Do you have access to a sandbox, a shovel, and some dirt? Try the project outside. Create a large pile of loose material: dirt covered with a layer of sand (similar to the flour covered with cocoa powder). Ask an adult for help dropping a larger ball, like a basketball, from a higher location (like standing on a ladder).
- For a more colorful project, use colored sand or sprinkles instead of cocoa powder. Create a rainbow of different layers, or different patterns on the surface, as shown in this video. What do your resulting craters look like?
- Do you have a smartphone with a slow-motion camera setting? Try filming your meteorite impacts in slow motion! What do you see when you watch the videos?
