How Big Are the Planets?
In this activity, students will construct a scale model of the major components of the Solar System. By creating this model, students will avoid misconceptions concerning the relative sizes of the planets and Sun in the Solar System.
The student will gain an understanding of the relative size of the objects in the Solar System.
Model of the Sun (cloth model 11 ½ feet in diameter)
For each team of two or three students
1-4 sheets of construction paper
1 planet data sheet (copy)
1 roll masking tape
1. Begin by asking the following:
What is the Solar System? What kinds of objects make
up the Solar System? What are its largest and most important components?
The student should reach the conclusion that the Solar System consists of a star and the objects that travel around it. Students should be lead to realize that the largest and most important components of the Solar System are the Sun and planets.
2. Tell the students that they will create a scale model that represents the relative sizes of the planets.
3. Divide the class into teams of two or three. Distribute materials.
4. Assign each team a Solar System object (planet). Ask each team to keep the identity of their object a secret (Secrecy allows the students to discover the relationship of the sizes of the planets after they make their own predictions.
5. Ask students to draw and cut out a representation of their planet on the paper. They should use the data sheet to determine the correct diameter for the circle that they make (Pluto will be too small to cut out easily and should jut be drawn to the correct size.
6. On the board, list numbers 1-9. Have one student from each team tape their planet next to one of the numbers. No particular order for the planets is needed, in fact a random order often helps the discovery process.
7. Ask the students as a class to determine which object represents which planet. Write the answers under each planet. Allow a free discussion and debate (referring students to their data sheet and providing assistance when needed) so that students will eventually arrive at the correct labels.
8. Ask the students:
What major part of the Solar System is still Missing? How does this
last component compare to the planets in size?
Students should realize that the Sun is not yet a part of the model. Allow them to make predictions concerning the relative size of the Sun.
9. Take out the cloth model of the Sun. Open it up and have the students surround it. For effect, remove the planets from the board and tape them onto the Sun. Allow the students to discuss the enormous size of the Sun in comparison to the planets. Point out that the Sun makes up over 99% of the matter in the Solar System.
Planet Data Reference Sheet
(table available in print form)
These sizes are to a rough scale.
6500 miles = 1 inch
If you are teaching an upper grade and would like your students to do the math, the number of miles divided by 6500 will give diameter in inches.