Make a Comet
1. Provide the children with a variety of comet pictures and diagrams. After they have had a few minutes to examine the pictures, ask them to describe, as specifically as possible, what they observe in the pictures. Encourage creative answers, but guide the children toward specific observations about the general structure of comets and the shape of comet orbital paths, as well as the direction and length of comet tails relative to our Sun. Some starting points for comet images are:
Comet Observation Home Page of the Jet Propulsion Laboratory
Views of the Solar System Comet Introduction Page
The Nine Planets Comet Page
Gary Kronk's Comets and Meteor Showers Page
The major parts of comets include the nucleus, coma, hydrogen cloud, dust tail, and gas tail.
2. Ask each child to use the assembled art materials to construct his/her own model of a comet. Individual creativity should be encouraged by suggesting that the children use a variety of the available comet construction materials in their model. Emphasize that their model should include representations of the principle structures of comets (nucleus, coma, hydrogen cloud, dust tail, and gas tail). Encourage the children to name their comet.
Provide adequate time (20-30 minutes) for the children to build their models.
3. In small groups of 3 to 5, have the children explain to their group how the various parts illustrated in their model comet represent a real comet. If there is time, ask for a few volunteers to present their model to the entire group.
4. In a large open space, using the large ball to represent our Sun, ask the children to lay their comets on the floor or ground around the Sun. After all the comets are placed, ask the children to examine the comet placements to see if they accurately represent the elliptical orbital paths of comets and the effect of sunlight and the solar wind on comet tail length and direction. As needed, have them adjust their models to accurately represent tail length and direction relative to our Sun.
What do you notice about the shape of the comet's orbital path? What do you notice about the comets' tails? Do the tails always point in the same direction? Are comet tails always the same length? What do you think causes comet tails?
5. Hold up a ball (e.g., a Styrofoam ball) with no tail. Ask the children in what part of the orbit a comet would have no tail. Consider the following questions when discussing Steps 5 and 6.
Do comets always have tails? Are tails always visible? During which portions of the comet's orbit will the tails be longest? Shortest? Is it possible for a comet's tail to precede it? What do you think is the cause of changing tail length? What do you think is the cause of changing tail direction?
6. Have the children walk around (orbit) the Sun while constantly orienting their comet tails in the correct direction relative to our Sun.
7. Challenge the children to consider how variables such as comet size, orbital period, and composition might affect the appearance of comets from Earth.