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ASTR 101- Solar System Astronomy- Lab 1 - Scale of the Solar System

Lab 1: Scale of the Solar System


Roll of toilet paper or printer tape

Colored markers or pencils (at least two colors)

Measuring tape, ruler, or meter stick


1. Unroll your paper until you have a length that is about equal to your “wingspan” (the length from fingertips to fingertips when you spread your arms apart).

2. On one end of the strip, draw and label the Sun. On the other end, draw and label Pluto. Remember that Pluto is no longer considered a major planet, but it is at the inner edge of the Kuiper Belt.

3. In between the Sun and Pluto, draw and label where you think the rest of the planet orbits are. Also place the asteroid belt. In order to do this, think about the relative distances, or spacing, between the planets.

4. Use the data table below to convert the actual distances between the planets to positions on your strip of paper.

For example, the distance between Pluto and the Sun is 5.91 X 109 kilometers.

Measure the length of your strip in centimeters (between the Sun and Pluto). For your

conversions, you will use the scale factor:

Here is an example of the calculations you will need to do:

If your measured distance between the Sun and Pluto on your strip is 100 cm (it will actually be much longer than this), and wanted to see what the scaled distance between the Sun and Mercury is, then you would calculate

5. Record the length of your strip of paper here: 132.08

6. Show your scale factor fraction here: 132.08/(5.91*10^9)

7. As you calculate the scaled distances for the planets on your strip, enter that value in the table.


Semi-major axis (km)

Scaled Distance Calculated (cm)





5.83 x 107



1.08 x 108



1.50 x 108



2.27 x 108


Asteroid Belt

3.28 X 108 to 4.77 X 108

7.33 to



7.78 x 108



1.43 x 109



2.87 x 109



4.50 x 109



5.91 x 109


8. Once your table is complete, use a different color to mark the actual positions of the planets and asteroid belt on your strip. Include a key to indicate which color are your predictions and which are the actual locations. The distances you calculated are how far the planet is from the Sun in centimeters.

9. Write your name on your finished Solar System.

10. Take a photo of your Solar System. (Preferably, take a photo of the inner half and then the outer half so it’s easier for me to see.)

11. Important! If you do not include the photos with your lab, or your name is not on the paper, you will lose points.

12. Answer the Questions below.

13. Submit this lab sheet (with steps 6, 7, the table, and answered Questions), as well as the photos, in the Submission Area for Lab 1 in Module 2. You can either insert the photos into this document or upload them as separate files.


1. Compare your estimated positions to the actual positions. Are there differences? What surprises you most about the differences you see?

Yes there are differences in the distances.

I was surprised to see how close the first planets are close to earth than what people think. It was predictable that they might be close but that was not how close I expected comparing the wingspan size I had used.

2. We often refer to the “inner planets” and “outer planets”. Describe the actual positions of the planets on your strip which illustrate this distinction. Where is the “split” between inner and outer planets?

The inner plants are very close to the sun than the outer planets that are further from the sun and more spread out than the inner planets. The asteroid belt shows the distinction with a split between the planets Mars and Jupiter.

3. Some of the planets much further out than Earth are brighter in Earth’s night sky than planets closer to Earth. What could that tell us about those brighter outer planets?

The size of the planet might be having an effect. In the case of some large planets like Jupiter, we can assume that it reflects more light from the sun due to the size hence can be seen brightly visible in the sky at night when the earth is dark.

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