A Scale Model of the Solar System

Name:____________________________________

Part I: Introduction to our Scale:

Let's have a volleyball (diameter 8.5 inches) represent the Sun in a scale model of our Solar System. The Sun is really 1,390,000 km in diameter! So the scale of our model is about 1 inch for every 160,000 km, or about 1 inch for every 100,000 miles!

  1. Write down how big you think the Earth will be in this scale model (pinhead, marble, golf ball, baseball, other?).





  2. Fill in these blanks as I give them to you. The Earth's diameter is about 12,756 km. In our scale, this is well represented by a peppercorn about 0.08 inches in diameter!

Part II: Sizes of the Objects

  1. Here is a table giving each object in our model of the Solar System. Fill in the table as we discuss it.

OBJECT   DIAMETER (km)   REPRESENTATIVE OBJECT   DISTANCE (AU)   SCALED DISTANCE (feet)
Sun   1,391,980 volleyball 0. 0.
Mercury   4,878   pinhead 0.3871   30
Venus   12,104   peppercorn 0.7233   54
Earth   12,756   peppercorn 1.0   75
Mars   6,796   pinhead 1.5237   117
Jupiter   142,988   steel ball bearing 5.2028   396
Saturn   120,660   hazelnut 9.5388   726
Uranus   51,118   coffee bean 19.18   1461
Neptune   49,500   coffee bean 30.0611   2286
Pluto   2,302   small pinhead 39.44   3000

Notice that even Jupiter (the largest planet) is much, much smaller than the Sun!

Part III: Distances Between the Objects

  1. Without doing any calculations, tell me how big you think our model of the entire solar system will be? Will it fit on a table? Inside this room? Inside this building? Inside Campus? Inside La Crosse?





    The distances given in the table above are the average distances between the Sun and the orbit of each planet. The unit of distance used is the Astronomical Unit (AU): 1 AU = the distance between the Earth and the Sun, which is 149,597,900 km (about 90 million miles).

  2. Using this scale, we can calculate that Mercury is (on average) 57,909,400 km from the Sun. In our scale model of the solar system, this is almost 10 yards!

  3. Clearly, we will have to leave this room to get a visual picture of the size of the solar system! As we go on a tour of our scale-model, fill in the remaining column of the Table above.

Part IV: Our Place in the Universe

  1. The nearest star (other than the Sun) is 4.28 light years away! It takes light 4.28 years to go from that star to us! This is 265,608 AU! Guess how far away (in our scale model) this star would lie?




  2. At a distance of 265,608 AU, or 40,000,000,000,000 (40 thousand million) km, the next volleyball-sized object in our scaled model is about 6,900,000 yards away, or 3900 miles! No wonder the other stars all look faint relative to the Sun!