Solar System Lab
Purpose: To
demonstrate the size of our Solar System via scale models. This handout presents this as a participatory
demonstration, although it can be modified to be a kind of formal lab exercise
with calculations.
Equipment: Orange beach ball with smiley face (40 cm diameter), containers of Play Dough, meter stick graduated in millimeters, human legs with ability to approximate one-meter per pace.
Procedure: Scaling the Sun to a diameter of 40cm, how do the diameters and semi-major axes of the planets scale? Calculate these scaled dimensions, then create Play Dough models of the planets and pace off scaled relative distances either outdoors or in the hallway. (Caveat: Earth is about far as you’ll get indoors!)
Calculations: Since the smiley face beach ball is 40 cm in diameter and the Sun is 1,391,000 km in diameter, the scaling factor is 40cm/1,391,000km = 0.0000288cm/km. For the purposes of our calculations, the factors 0.288mm/1000 km and 0.000288m/Gm for planetary diameters and orbital semi-major axes, respectively, are most apropos.
Results of the
Calculations: (Note 1: You may want
to have your students do these as a calculator exercise. Note 2:
Here Pluto is still given the titular honor as a planet, but you will
find that this is irrelevant for this exercise since at the scale we’re using
this putative planet is over a mile away from our beach ball! Note 3: Our nearest stellar neighbor, the Alpha
Centauri triple-star system is thrown in for comparison. This system would be in
|
Body |
Diameter (km) |
Planet/Sun diameter ratio |
Scaled Diameter (mm) |
Orbital Radius (billions of meters) |
Scaled Orbital Radius (m) |
Incremental Distance (m) – Equate to long paces |
|
Sun |
1,391,900 |
1 |
400 |
--------- |
--------- |
0 |
|
Mercury |
4,866 |
0.0035 |
1.4 |
57,950 |
17 |
17 |
|
Venus |
12,106 |
0.0087 |
3.5 |
108,110 |
31 |
14 |
|
Earth |
12,742 |
0.0092 |
3.7 |
149,570 |
43 |
12 |
|
Mars |
6,760 |
0.0048 |
1.9 |
227,840 |
66 |
23 |
|
Jupiter |
139,516 |
0.1002 |
40.0 |
778,140 |
224 |
158 |
|
Saturn |
116,438 |
0.0837 |
33.4 |
1,427,000 |
411 |
187 |
|
Uranus |
46,940 |
0.0337 |
13.5 |
2,870,300 |
827 |
416 |
|
|
45,432 |
0.0326 |
13.0 |
4,499,900 |
1,296 |
469 |
|
Pluto |
2,274 |
0.0016 |
0.6 |
5,913,000 |
1,703 |
407 |
|
α-Centauri system |
-------- |
--------- |
--------- |
---------- |
-------- |
11,600km* |
*More than the distance from Rensselaer to Iraq
The data for this exercise come from
http://www.exploratorium.edu/ronh/solar_system/