Craters: The Ins and Outs

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Materials

• chocolate pudding; as much as possible
• baking pan; as large as possible
• rubber spatula or table knife
• chocolate chips of different sizes, if possible
• Hershey's kisses

Procedure

1. Make the pudding.
2. Smooth the surface of the pudding in the pan.
3. From 1 meter (or yard) directly above the surface of the pudding, drop chocolate chips and kisses of different sizes into the pudding (one at a time). For each one dropped, measure the diameter of the crater and record it in the data table below.
4. Smooth the surface of the pudding, if necessary, and then repeat the previous step, but from as great a height as possible, perhaps off a staircase.
5. Throw a chip sideways to get it to skip along the surface of the pudding. Describe the appearances that result.

Trial	Impact Body size	Crater Diameter	Other observations?
1	1	mm
2	1	mm
3	1	mm
4	1	mm
5	1	mm
6	1	mm
7	1	mm
8	1	mm

Questions

1. The bigger the impact body, the | bigger | smaller | the crater that results.
2. The greater the impact velocity, the | bigger | smaller | the crater that results.
3. Can you identify crater "rims"?
   • Which is steeper, the inside or outside edge of the rim?
   • Which is higher, the rim of a larger or a smaller crater?
4. Do any craters have "peaks" in the center?
   • Are they larger or smaller craters?
5. Do you see any "ejecta," material ejected outside the crater from the impact?
   • If ejecta sprays in all directions it is called "rays."
6. Can you tell which craters formed before others?
7. True or False? The Moon is the only body in the solar system that has craters.
8. True or False? The Earth has experienced impacts about as often as the Moon.
   • If so, why isn't the surface of the Earth cratered like the Moon's?

Discussion

• The chocolate chips and kisses represent impact bodies, such as meteorites, asteroids, or comets.
• Find specific craters on a Moon map.
• If central peaks are not visible in the pudding, model them by dropping chips into a beaker of water. If an impact body is large or fast enough, it may melt lunar rocks on impact and behave much like the water.
• All rocky planets and satellites have craters (e.g., Mercury, or the two moons of Mars).
• The Earth has been hit just as often as the Moon, but the surface of the Earth changes through geological processes such as weathering and plate tectonics. Consequently, most impact sites are erased from view. Meteor crater in Arizona is a famous impact site.
• Rays will be more obvious from recent craters.
• Many craters on the Moon are very large. The largest is about 700 miles (1120 km) wide.

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