Make a Comet in Your Classroom!
Meteor showers occur when the Earth passes through a comet's orbit, and leftover comet debris (rocks, etc.) bombards the Earth.
Materials
Self-seal Baggies, Dry Ice, Ammonia, Water, Dirt, Light Corn Syrup or Vegetable Oil, Cooler for dry ice, Tablespoons and Measuring Cups, Safety Goggles, Wet Wipes, Oven Mitts, Plastic Floor Covering
Instructions
1. Using oven mitts, put about 1/4 cup of dry ice in a resealable bag.
2. Add about 1/4 cup ammonia / water mixture (1 capful of ordinary household ammonia in one cup of water). This mixture will bubble and a "tail" will form as the dry ice warms.
3. Add about one tablespoon of light corn syrup, vegetable oil, or colored water and a spoonful of dirt. Seal bag and shake gently.
4. Place the bag on the plastic floor covering. Do not hold the bag after it has been shaken! The gases will expand until the bag pops.
5. The comet will sublimate, or turn directly from a solid to a gas, like comets do in space when heated by the sun. The "tail" is gaseous carbon dioxide escaping through small holes in the frozen water. After a while, the comet will become a crater-filled ice ball as the carbon dioxide sublimates.
What’s Going On?
Why does the bag pop? A build-up of carbon dioxide gas is caused as the dry ice mixture sublimates from solid to gas. The water represents the water present in a comet. The ammonia represents methane and other simple liquids and gases found in comets. The corn syrup, vegetable oil, or colored water represents the compounds that contain hydrogen and carbon found in comets. The dirt and sand represent the carbon, dirt, and dust also found in comets.
Safety
Dry ice is available from a dry ice or carbon dioxide sales company. Do not handle this with bare hands as it is extremely cold, approximately -76 ºF, and can cause frostbite! Do not directly inhale ammonia fumes.
Disposal
Let the "comet" sit at room temperature until the dry ice has sublimated, and the ammonia has evaporated. Throw remaining pieces in the trash.
Relevant Ohio Science Content Standards
Earth and Space Sciences: 8.1, 8.3, 9.3
Physical Sciences: 1.3, 1.4, 4.1, 4.4
Additional Resources Zoom Astronomy | Science@NASA
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