Solar System Scale: Miniature Model
Our solar system consists basically of the Sun, the eight planets (celestial bodies that orbit a sun), and their moons, asteroids, comets, and space debris. The boundary of the solar system is called the heliopause, which is the limit the solar winds reach. Solar winds are streams of charges escaping from the Sun's atmosphere and flowing into the solar system. From the heliopause, the solar system is about 18.6 billion miles (29.8 billion km) across. The Sun is the largest celestial body in the solar system, having a diameter of about 870,000 miles (1,392,000 km). Pluto is the smallest planet at about 1,434 miles (2,294 km) across. All of the millions of asteroids and comets are much smaller than Pluto.
In this project, you will make a 3-D model to represent the sizes of celestial bodies in the solar system. You will also learn how to represent the distances between planets and between planets and their moons.
Purpose: To build a 3-D scale model of Earth.
- drawing compass
- metric ruler
- sheet of colored poster board
- index card
- The diameter of Earth is about 7,973 miles (12,757 km). Using the metric scale of 1 cm = 3,000 km, calculate the diameter of the model Earth as follows:
- Earth's actual diameter ÷ 3,000 km/cm = model Earth's diameter
- 12,757 km ÷ 3,000 km/cm = 4.252 cm
- Use the compass to draw two circles with diameters of 4 cm (radius 2 cm) on the poster board.
- Cut out the circles, then cut along a straight line (radius) from the circumference to the center of each circle.
- Fit the two circles together at a 90° angle to each other (see Figure 10.1)
- Prepare a legend showing the scale of the model by folding the index card in half. Write the scale, "1 cm = 3,000 km," on one side of the card. Stand the card alongside the model.
Rounding the number to the closest centimeter, the model Earth's diameter would be 4 cm.
You have made a scale model of Earth.
A scale model is a replica made in proportion to the object it represents. A solar system is a group of celestial bodies that orbits a star called a sun. Planets are large celestial bodies that orbit a sun. Models of bodies in our solar system, such as Earth, are valuable because they allow an observer to compare the relative sizes and distances of large things more easily.
Try New Approaches
How does the size of Earth compare with the other planets in the solar system? Make more scale models, using the diameters of the planets given in Appendix 3. Science Fair Hint: Attach threads to the models and suspend them from a 4-foot (1.2-m) or longer dowel. Support the ends of the dowel, then take a picture of the models. Use the photo and models in your science fair display.