Sizing Up the Solar System

To investigate and design various models of size and distance related to the solar system.

This investigation focuses on the part of the universe that is most familiar to students: the solar system. Students' grasps of the ideas of composition and magnitude of the universe have to develop over time. In middle school, students can begin to add more detail to their picture of the solar system and the universe, paying increasing attention to matters of scale and distance.

Ideas in this lesson are also related to the concepts found in the following benchmarks:

• 4A The Physical Setting: The Universe, (6-8) #1
• 4A The Physical Setting: The Universe, (6-8) #3

Materials:

• materials listed on the Make Models of the Planets website
• materials to build a physical model of the solar system
• materials for The Sun and Earth Size Comparison activity on the Athena Project website

Begin by asking the class to brainstorm about all that they already know about the solar system.

List all of the student ideas that are mentioned, but focus their thinking on scale and distance by asking questions such as:

• What is the closest planet to the sun?
• Which is the smallest planet?

Figuring out and constructing models of size and distance—for example, of the planets within the solar system—is a worthwhile activity for middle school students. Models with three dimensions are preferable to pictures and diagrams, although you can begin with scale drawings. You can use the activity Make Models of the Planets on the Athena Project site as a class project to introduce students to the ideas of size and distance in the solar system. In this activity, students draw “scale” pictures of the planets.

Each student should also experience trying to fashion a physical model of the solar system in which the same scale is used for the sizes of the objects and the distances between them (as distinct from most illustrations, in which distances are underrepresented by a factor of 10 or more).

The Internet provides teachers with a number of different strategies and ideas for building a Solar System model, such as:

The Exploratorium Webmaster’s page contains a JavaScript calculator Build a Solar System that students can use to build a model of the solar system.

Divide the class into groups of two or three and let students type in the diameter of the sun they wish to use. The program calculates the diameter of the other bodies in the solar system, based on the diameter they have selected. By trying different numbers, students can get an idea of the relationship of the sizes of the various planets. They can also get an idea of a practical scale to use that will enable them to work with a model that is neither too large nor too small to be easily constructed.

Next, each group should work together to build a solar system model. The models should focus on distance and scale. Students need not include moons or satellites in their models. However, if they do, they must maintain the proportions of distance and scale. Have the groups work in phases. The first phase is the design phase. The group should develop written plans which describe the materials they will use, the scale of their solar system, the sources they used, and so on. In addition to The Athena Project, The Nine Planets website is an excellent source of information that students might find useful in constructing their model.

Work with each group to approve the final plan. Make sure to provide time for students to reflect upon the feedback they receive both from you and from members of the larger group. The second phase is the construction phase. Allow the group several weeks to construct their models and instruct them to keep notes on which aspects of their plans worked best and which didn’t. Advise students to use simple materials. Remind them that the important part of their model is that it shows the sun and the planets in appropriate scale relative to size and distance from the sun and each other. A written report should accompany each model.

How to Collect Solar System Trading Cards is an online activity from the Amazing Space website. The accompanying Teacher Page provides teaching suggestions that can be used to assess student knowledge of the planets and the solar system.

Do The Sun and Earth Size Comparison on the Athena Project website to assess student understanding. In this activity, students explore the size comparison of Earth and Sun using measured values and by making a scale model using pennies. Students are asked to assess the results of both comparisons in writing.

Students should back up their understanding of the solar system and the universe with activities using a variety of astronomical tools. Student access to star finders, telescopes, computer simulations of planetary orbits, or a planetarium can be useful at this level.

There are many excellent lessons on the Athena Project website that can extend student understanding of the ideas in the benchmarks related to the sun and the Solar System. Some of these are highlighted below.

Some experiences with how apparent positions of objects differ from different points of observation help to make plausible the estimation of distances to the moon and the sun. Sunspot Perspective Experiment, in which students investigate perspectives of spheres and disks, can be useful in this regard.

Dance of the Planets has students collect and graph data they have gathered about the position of a planet as it moves around the Sun.

Take a Spin Through the Solar System, a teacher developed Internet-based investigation of how different planets, and even the Sun, rotate around their axes from the Center for Science Education at the U.C. Berkeley Space Sciences Laboratory.

The activity Exploring the Planets: Our Solar System, from the Smithsonian, provides physical data, relative sizes of the planets, and the relative distances of the planets from the sun.

The constellations, sun, moon, and planets have always figured in the efforts of people to explain themselves and their world through stories, myths, religions, and philosophies. You can follow the links in The Nine Planets to learn more about heavenly bodies and human culture.

The Hawaii Space Grant Consortium website includes a section called Exploring Planets in the Classroom: Hands-on Activities. The activities in this resource explore physical properties of planets such as the density of planetary matter, gravitational attraction, and orbital forces.

Created :12/06/2000