Lunar landscaping

How are craters formed?

Craters photographed by the Apollo 11 lunar lander.

Craters photographed by the Apollo 11 lunar lander. Credit: NASA

You will need:

  • 2 cups of flour
  • ½ cup of cocoa
  • A tray (baking tray or similar)
  • Small marbles or ball bearings, a mix of sizes is preferable
  • Newspaper or plastic sheet

What to do:

  1. Spread the newspaper out on the floor under where the tray will go. Use plenty.
  2. Place a thick layer of flour in the tray. Sprinkle a fine layer of cocoa on top of the flour.
  3. Drop small marbles from different heights into the tray of flour. What happens?
  4. Try dropping small pinches of flour to simulate slower, smaller impacts.
  5. See if you can determine if there is a relationship between the height from which the marbles drop to the size of the craters formed.
  6. Does the mass of the mass or size of the marble has an effect on crater size?

What is happening?

All craters on the Moon have been formed by the impact of meteorites that hit its surface. Most craters occurred over 3.8 billion years ago when the Moon was newly formed. The energy that was released from the meteorite explosions created craters that were up to 20 times the size of the meteorite. The Moon’s biggest craters measure hundreds of kilometres in diameter.

Craters differ from each other depending on how they were formed. Some craters have dark, flat floors because molten lava has flowed from inside the Moon to fill the deep holes left by meteorites. The lunar ‘seas’ were formed this way. Many craters have mountains in their centre, caused by the ground ‘bouncing’ back after impact.