We have two activities that teach students about the components of a comet. "How to Make a Comet Using Craft Materials," more often called the Comet-on-a-Stick activity, is a hands-on project appropriate for grades 2 through 6. "Create a Comet With Dry Ice" is a demonstration-only activity since it involves dry ice, which is very cold. It is great for grades 4 and up. Click on the images below or scroll down the page to find information about that activity.
For both activities, it is important that students know that any model they make is a good one. Comets come in all shapes and sizes and scientists learn more about them with every observation they make.
How to Make a Comet Using Craft Materials
This information is intended to supplement the video demonstration you can watch here: http://www.jpl.nasa.gov/education/videos/playVideo.cfm?videoID=16 .
Science as Inquiry
Earth and Space Science
-- Styrofoam balls (1 per student)
-- Popsicle sticks or plastic straws (1 per student)
-- Assortment of pompoms, cotton balls, packing "popcorn" or any other small material that can be glued to styrofoam balls
-- Pipe cleaners (at least 2 per student)
-- Tin foil
-- Pillow filling or big pieces of cotton that can be pulled apart
-- Clear plastic wrap or cellophane
-- Ribbon or any material that can be used as a tail
-- Craft glue
-- Clear tape
1. Insert straw or popsicle stick into Styrofoam ball. The ball is the comet nucleus, the stick is merely to hold the comet.
2. Nucleus: Comets have uneven shapes so glue pompons or other materials to the ball so it has an uneven look.
3. Comets are icy so glue or tape pieces of tin foil to the ball.
4. To make the coma, or comet cloud, glue or tape pillow filling, cellophane or plastic wrap around the decorated ball.
5. To create the dust tail and ion tail, push pipe cleaners into ball and/or tape ribbon onto outside of decorated ball.
For more details on the activity, go to http://deepimpact.umd.edu/educ/CometStick.html .
This information is intended to supplement the video demonstration you can watch here: http://www.jpl.nasa.gov/education/videos/playVideo.cfm?videoID=17 .
This activity is fairly straight forward once you get the hang of it. Try it at home a few times to feel comfortable doing it before going in front of a class.
Motions and Forces
Transfer of Energy
Earth in the Solar System
-- 5 pounds dry ice, finely crushed
-- Insulated container to hold dry ice
-- Thick gloves to handle dry ice (check at online chemistry stores or hardware stores)
-- Mallet to crush dry ice
-- Large plastic bowl
-- Towel or pillowcase (it will get very dirty)
-- Several large plastic garbage bags, 12 gallons or larger, heavy strength
-- Flat tray
-- 1 liter water
-- About 2 cups dirt (clean out twigs and little pebbles)
-- 1 tablespoon or less starch
-- 1 tablespoon or less dark corn syrup or soda
-- 1 tablespoon or less vinegar
-- 1 tablespoon or less rubbing alcohol
-- Hair dryer
1. Crushing the dry ice will take some time and can be done ahead of the demo. To prep the dry ice, put on thick gloves and place the dry ice in a towel or pillowcase. You can purchase dry ice in blocks or as inch-size granules. A 5-pound block will be almost intact after several hours. In either case, use the mallet to break the ice into small bits. You need to have at least 50 percent of your dry ice as a powder, which will make the water freeze and hold your comet together. Keep the dry ice in a cooler after you have crushed it. After crushing, store the dry ice back in your insulated container.
2. Once students arrive, explain that you will be making a model of a comet that will show jets coming from the comet model. Explain that they must stand a safe distance back since dry ice can cause injuries. Tiny pieces of dry ice will shoot out, especially when you crush it and while you add water. That is why you have goggles and gloves.
3. Line the bowl with a plastic bag.
4. Add to lined bowl 1 liter of water, dirt, starch, corn syrup or soda, vinegar and alcohol. As you do this, explain that comets have lots of ice and water. In our comet model, dirt represents the dust, minerals and water found in comets; starch helps hold the model together; the syrup or soda are organics and give the comet a dark appearance; vinegar represents amino acids in a comet and rubbing alcohol represents methanol found in comets. Do not add too much alcohol as it has an antifreeze effect.
4. Mix ingredients and stir in dry ice. Students will love this part since a murky white cloud puffs up as moisture in the air is being frozen out by the gas that is coming out of dry ice.
5. Once all the dry ice is in the bowl, pick up the sides of the bag and use them to form the mixture into a large clump. Add more water as needed. The mixture will start to thicken as the dry ice freezes the water. You can feel the clump forming through the plastic bag. If the mixture does not hold together, add more water. This part takes a bit of experience. However, you may get lucky on the first try. You will certainly have a good feel for the proportion of ice-to-water on the third try.
6. Once you see you have a clump, take it out of the bag and show it to students. You should see gas jets coming off the comet. If your model falls apart, it’s okay. Comets frequently disintegrate as they come closer to the sun!
7. For added effect, have students take turns holding the flashlight and hair dryer close together and pointing at the comet. The flashlight represents the sun and the dryer is the solar wind. You should see the jets moving away as the heat from the dryer pushes the gas away.
8. To clean up, place your comet in a sink and let it melt.