Below is both the lab for the students and a Teacher's Guide.
Our project is to create a scale model of the Solar System as it is now (the model will change as the planets move around the Sun). We will make a 10,000,000,000:1 model of the Solar System. This means that the distances in the model will be 10,000,000,000 times smaller than they are in the real Solar System. This scale was chosen so that the model can be constructed on the Yerkes grounds.
There are three steps to follow for each planet (plus the Sun):
It is often convenient to convert measurements to different units. For example, suppose you found that the distance to a model planet was 0.005 kilometers. We have no convenient way to measure this distance, since none of our measuring devices are marked in kilometers. However, if we multiply by 1, the number should not change:
1000 meters (0.005 kilometer) X ------------- = 5 meters 1 kilometer
Planet Dist(kilometers) Dist(miles) Dist(minutes) Mercury 47,500,000 29,500,000 2.64 Venus 109,000,000 67,600,000 6.06 Earth 152,000,000 94,300,000 8.44 Mars 221,000,000 137,000,000 12.3 Jupiter 810,000,000 503,000,000 45.0 Saturn 1,450,000,000 904,000,000 80.6 Uranus 2,940,000,000 1,830,000,000 163 Neptune 4,510,000,000 2,810,000,000 251 Pluto 4,460,000,000 2,780,000,000 248
Planet Diam(kilometers) Diam(miles) Fraction of Earth Mercury 4,880 3,032 0.38 Venus 12,100 7,519 0.95 Earth 12,756 7,927 1.00 Mars 6,784 4,215 0.53 Jupiter 143,200 88,984 11.20 Saturn 120,000 74,568 9.41 Uranus 51,800 32,189 4.10 Neptune 49,500 30,759 3.90 Pluto 2,600 1,616 0.20
Planet Distance Diameter Angle Mercury 112 Venus 262 Earth 315 Mars 52 Jupiter 227 Saturn 338 Uranus 294 Neptune 292 Pluto 237
Even using this large tract of land, the largest planet (Jupiter) is 1.4 cm and the smallest planet (Pluto) is 0.26 mm. The students went out with their "planets" and a stake to put in the ground next to it so they could find them later (we put the planets in bottle tops next to the stakes). Here are some suggestions for planets:
Planet Size Object Mercury .49 mm pencil lead, sand Venus 1.2 mm poppy seed Earth 1.3 mm tip of a rice grain Mars .68 mm pin head Jupiter 14 mm acorn Saturn 12. mm marble Uranus 5.2 mm popcorn Neptune 5.0 mm popcorn Pluto .26 mm largish sugar grainThe Sun is about 14 centimeters, so it is a large softball. We used a one pint canning jar, even though it wasn't spherical.
After the students had individually put their planets out there, we walked as a group from planet to planet, starting with the inner planets. It is a good idea to stand at the Earth and look at the angular diameter of the Sun, and to look for the positions of the planets from our point of view. You will find that some of the planets are near the Sun, and cannot be observed this time of year. At each planet, the student with that planet told us the name of the planet, the distance, the size, and what object we were using for that planet in the model. They also told us what they had learned in other classes about that planet.
Important Disclaimers and Caveats: