Recommended by Stacy DeVeau, Arizona NASA Educator Resource Center, Embry-Riddle Aeronautical University
This activity will help us to better understand the distances between the planets and their distances from the sun in our solar system. As students build their models, show planetary images from solar system lithographs in binder and read solar system trading card facts, or ask them what they recall about each body. Students may color their planets as they label them.
1. Start with a length of register tape the span of the letter "V" made with your arms (~1m).
2. Sun & Pluto (on the edges):
3. Uranus (1/2):
4. Saturn (1/4) and Neptune (3/4):
5. Jupiter (1/8):
6. Asteroid Belt (1/16):
7. Earth (inside 1/32), Mars (outside 1/32):
8. Mercury & Venus (between Earth & Sun):
Be sure to have everyone put their names on their tapes and fold them up to put it in their pockets. But before you put them away, here are some questions you might ask to get them thinking about what they can get from building this model.
1. Are there any surprises? Look how empty the outer solar system is: there is a reason they call it space! And how crowded the inner solar system is (relatively speaking). Even though it looks crowded in this model, are our closest planets very close? What's the farthest distance humans have ever travelled away from Earth? The moon!
2. Do you know anything about the physical properties of the ones that are spread out versus the ones that are crowded in close to the Sun? All the inner ones are small and rocky and the outer ones are gassy giants (except small, icy Pluto).
3. Given this spacing, why do you think little, rocky Venus can outshine giant Jupiter in the night sky? Both are covered with highly reflective clouds, and although it is much smaller, Venus is also much, much closer.
4. Does anyone know where the Eris, the largest dwarf planet would go on this model? At 97 A.U., it would more than double the size of the model. Pluto is on average 40 A.U. [A.U. stands for Astronomical Unit, roughly the mean distance from the Earth to the Sun. 1 AU = 149,597,870.691 kilometers, or about 93 million miles.]
5. On this scale (1 m = 40 A.U.) where would the nearest star* be? After some guesses you could bring out your pocket calculator to use in getting how far away the star would be. This allows you to talk about how far is a light year and do the calculations to find that the next nearest star on this scale is about 7 km (4.2 miles) away. They could then take out a local map to see what is that far away from the class. You'd need a lot more register tape!
6. [Calculations: A light year, the distance light travels in one year, is about 63,240 A.U. (about 9,460,000,000,000 km). The nearest star is *Proxima Centauri (visible from the Southern Hemisphere), at 4.2 light years. So, 4.2 l.y. x 63,240 A.U./l.y. x 1 m/ 40 A.U. = 6640.2 m = about 7 km.]
7. You can keep this model to explain the vast distances in the solar system to your friends and family.