Creating Moon craters
Credit: NASA
If you've ever seen a photo of Earth's Moon, you may have noticed that there are numerous craters on its surface. Some of them are bigger than cities on Earth! About 80% of the Moon's surface is covered in craters. These are impact marks left on the Moon's surface by ancient meteorites or other celestial bodies. Meteorite impacts have been shaping Earth and the Moon for over 4 billion years. Craters on the Moon are virtually permanent, as opposed to those on Earth. Earth has processes such as erosion, which constantly changes Earth's landscape. As a result, traces of craters are harder to find.
In this activity, you will be recreating the Moon's craters and exploring how a crater's size, ejecta, and characteristics depend on the incoming meteorite's mass, velocity, angle and height. The Moon's Tycho crater (bottom left), which looks like the navel on an orange, is 86 km in diameter, almost 5 km deep and approximately 108 million years old.
Did you know?
- The Moon does not shine with its own light. It simply reflects the light coming from the Sun.
- There is no wind or air on the Moon to move the soil, so its surface is covered with old and new impact craters.
- Only 12 astronauts have walked on the Moon. They were all Americans who flew on six different missions between and .
- The United States, the Soviet Union (now Russia) and China have landed unmanned spacecraft on the Moon.
You will need:
- A large baking tray or plastic container that is about 6 cm deep
- Flour (to a depth of about 5 cm in the tray or container)
- Cinnamon or cocoa (to a depth of about 1 cm in the tray or container)
- Newspapers
- A sifter
- 4 or 5 rocks of different shapes and sizes
- Safety glasses
- Ruler (optional)
How to make your craters:
- Lay down several sheets of newspaper for easy cleanup.
- Pour and evenly spread 5 cm of flour in your baking tray or plastic container.
- Using the sifter, evenly sift 1 cm of cinnamon or cocoa on top of the flour. This will be the Moon's surface.
- Hold your first rock 40 cm to 50 cm above the tray or container.
- Drop it into the tray or container to simulate a meteorite impact.
- Carefully remove the rock and observe the crater created. The material that was ejected is called the ejecta.
- Experiment by dropping differently sized rocks at various angles and heights, and see how one ejecta pattern differs from the next.
Earthrise as captured by the crew of Apollo 8 on . It was the first manned mission to enter lunar orbit. (Credit: NASA)
How it works:
When you throw a rock, it gains kinetic energy (which means the energy that an object has because it is in motion). When the rock hits the flat, powdery surface, its kinetic energy is transferred to the powder and creates an impact crater. Try different heights (e.g. 1 metre, 2 metres) and different angles. The craters should change their shape depending on the speed, size and angle of the incoming meteorite. Higher-energy impacts make bigger craters, with debris shooting out from their centres as "rays." Throwing a rock at an angle makes an oblong crater.
Calculate the effects of a meteorite impact on the Moon, Earth and Mars using the Impact Calculator.
Terminology:
- Crater: a large, bowl-shaped cavity on the surface of a planet or the Moon, typically one caused by an explosion or the impact of a meteorite or other celestial body
- Meteorite: a fragment of matter from outer space that strikes the surface of a planet or the Moon
- Erosion: the process of being gradually worn away by wind, water or other natural agents
- Ejecta: material that is forced or thrown out, especially as a result of volcanic eruption, meteoritic impact or stellar explosion