Labs from YSI 94 :
Model of the Solar System.

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):

1. Calculate the size of the planet in our model by dividing the planet's diameter by 10,000,000,000. Then, find something about that size to use for the planet.
2. Calculate the distance the planet is away from the Sun by dividing the Sun-planet distance by 10,000,000,000.
3. Determine in what direction the planet is from the model Sun.

Information on units:

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 Statistics

Distances from the Sun to Planets

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

Sizes of Planets

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

Size of the Sun:

Our Model of the Universe

Planet  Distance   Diameter    Angle
Mercury                         112
Venus                           262
Earth                           315
Mars                             52
Jupiter                         227
Saturn                          338
Uranus                          294
Neptune                         292
Pluto                           237

Teachers' Guide

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 grain

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:

CARA's research and education programs are supported in part by the National Science Foundation under a cooperative agreement, grant number NSF OPP 89-20223. © Copyright 1998,1999,2000 by Center for Astrophysical Research in Antarctica. This copyright applies to all web pages and images created by CARA.