Activity at a Glance
Dry Ice Comet
Introduce children to the structure of comets and the interactions between comets and our Sun.
Dry ice and other items are used to construct a demonstration model of a comet that illustrates the comet nucleus, coma, and tails.
- Comets are composed of frozen water and gases, dust and rock, and a variety of organic materials.
- Heating from our Sun vaporizes frozen gases and water on the surface of comets.
- Sunlight and solar wind sweep the dust and gas of the coma into trailing tails. Because sunlight and solar wind always flow outward from our Sun's surface, the tails always point away from our Sun no matter what direction the comet is moving in its orbit. This means that the tails can be in front of the comet as the comet moves away from our Sun on its return to the outer part of its orbit.
- Comet tails increase in length as the comet-Sun distance decreases.
- A comet's gas tail points in the direction that the solar wind is streaming, in a straight line away from our Sun.
This activity is primarily intended for children ages 10–13, but is also appropriate for younger children ages 8–9.
- 5 pounds of dry ice
- Eye protection
- Thick work gloves or insulated rubber gloves
- Plastic bowl - large
- Paper grocery bag
- 13 gallon garbage bag
- Pie pan or flat tray
- 1 liter (34 ounces) of water
- 1 cup of soil
- Dash of ammonia
- Dash of alcohol
- Dash of cornstarch
- Dash of dark corn syrup
- Hairdryer with a low or cool setting
- Strong flashlight
Correlations to National Standards
Physical Science — Content Standard B
Motions and Forces
- The motion of an object can be described by its position, direction of motion, and speed. That motion can be measured and represented on a graph.
- An object that is not being subjected to a force will continue to move at a constant speed and in a straight line.
- If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on their direction and magnitude. Unbalanced forces will cause changes in the speed or direction of an object's motion.
Transfer of Energy
- Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways.
Earth and Space Science — Content Standard D
Earth in the Solar System
- The earth is the third planet from the sun in a system that includes the moon, the sun, eight other planets and their moons, and smaller objects, such as asteroids and comets.
- Most objects in the solar system are in regular and predictable motion.
- Gravity is the force that keeps planets in orbit around the sun and governs the rest of the motion in the solar system.