Students use adding machine tape to make a scale model of the solar system.
Students have various misconceptions about the solar system. Some individuals believe that the Earth is the center of the solar system and that it is also the largest object in the solar system. Students may believe that the solar system is very full of objects, or they may believe that other objects seen in the solar system come from outside and are not a part of the solar system.
Without going into much detail, current theories suggest that the solar system was formed just under five billion years ago when a cloud of interstellar gas and dust (a nebula) with a very slight rotation began to collapse and condense. As it condensed, the nebula also contracted. As the condensation and contraction continued, the rotation caused the nebula to flatten until it became a disc with a concentration in the center, the primordial sun. Meanwhile, solid particles condensed toward the inner concentration and accumulated to form planets. The denser material formed the rocky inner planets and the lighter matter formed the outer gaseous planets. The pressure of the solar radiation and the solar wind blew the solar system clean of most of the remaining matter that did not go into the planets.
As it stands now, 99.85% of the mass of the solar system is in the sun, and the planets take up another 0.135% of the mass. Thus, 99.985% of the mass of the solar system is to be found in the sun and its planets. The remaining 0.015% is distributed among the natural satellites, comets, meteoroids, asteroids (minor planets), and the interstellar medium itself. Therefore, given the volume of the solar system and the obvious concentrations of mass, the overall solar system is very empty. Even though objects are drawn into the center of the solar system by the gravitational pull of the sun, it is highly unlikely that anything large will hit our planet (once in 100 plus years has recently been given as the time between occurrences of a noticeable collision; once in 100,000 plus years between very large collisions). As an example of the vast emptiness of the solar system, picture the Rose Bowl as the inner solar system and an orange on the fifty-yard line as the sun. The planets would be like sand grains on the playing field. The chance of something from outside the stadium hitting one of those sand grains is very slim.
Create a scale model of the planets using the Planet Conversion Chart attached below.
Use the Solar System Model Rubric below to assess student work.
This lesson plan was adapted from Operational Physical Science, NSF grant #8751216 by Dr. Donald Kirwan.