Solar System Distance Activity

 Introduction
Our solar system is immense in size by normal standards. We think of the planets as revolving around the Sun, but rarely consider how far each planet is from the Sun. Furthermore, we fail to appreciate the even greater distances to the other stars. Astronomers use the distance from the Sun to the Earth as one "astronomical unit." This unit provides an easy way to calculate the distances of the other planets from the Sun.

Vocabulary -- astronomical unit (1 AU = approximately 150 million kilometers)

Activity
We will construct a distance model of the solar system to scale, using beads as planets. The chart below shows the planets and asteroid belt in order along with their distance from the Sun in astronomical units. First, complete the chart by multiplying each AU distance by our scale factor of 10cm per astronomical unit. Then, use the new distance to construct a scale model of our solar system. Cut a 4.5m piece of string. Use the distances in cm that you have calculated in the chart below to measure the distance from the Sun on the string to the appropriate planet and tie the colored bead in place. When finished, wrap your string solar system around the cardboard holder.

Planet		AU   Scale value (cm)   color
		       (*10cm/AU)

Sun               0.0AU  ________cm   yellow
Mercury         0.4AU  ________cm   solid red
Venus            0.7AU  ________cm   cream
Earth            1.0AU  ________cm   clear blue
Mars             1.5AU  ________cm   clear red
Asteroid 
belt               2.8AU  ________cm   black
Jupiter          5.0AU  ________cm  orange
Saturn        10.0AU  ________cm   clear gold
Uranus       19.0AU  ________cm   dark blue
Neptune     30.0AU  ________cm   light blue
Pluto          39.0AU  ________cm   brown


Consider if you were traveling at the speed of light it would take 8 minutes to travel from the Sun to the Earth (1 AU). It would take 4.3 years (traveling at the speed of light - 300,000 kilometers per second) to reach the next nearest star, Alpha Centauri!

Show the model to your teacher for a grade. You may keep the model!