Name_______________________________ Date_______________ Period__________

Our Solar System to Scale

In this lab you will calculate the relative size of the planets and the average orbital distance they are from the sun. You will also construct a scale diagram of the Solar System using the size of the planets their distance from the sun. Since the distances between planets are so much greater than their diameters we will have to use two different scales.

Hypotheses:

·         How do the sizes of the terrestrial planets compare to the gas giants? How do the sizes of all the planets compare to the Sun?

·         How do the distances between the terrestrial planets compare to the gas giants?

Materials:

• Meter stick/metric ruler
• Colored/White Paper
• Compass
• Markers/Colored Pencils
• Chart Paper
• Completed Planet Guide Sheets

Procedure A:  Size of the Planets

1. Complete  Data Table A
   1. Research and fill in the equatorial diameter (km) for each planet.
   2. Use the scale 7000 km = 1 cm to calculate the scale size of planets.
   3. Round your answers to the nearest tenths place.
   4. Complete calculations on scrap paper.

2. Using the scale diameters in Data Table A, construct circles representing the planets on white or colored paper. 
   1. If the diameter is large enough, use a drawing compass.  (But remember to use the radius which is one half of the diameter.)
   2. If the diameter is too small for the drawing compass, draw a line that is equal to the diameter.  Approximate the circle by drawing it “free-hand”.
   3. Label each circle with the name of the planet it represents.

3. Complete discussion questions #1-8.

                                           Data Table A- Size of the Planets

Procedure B:  Relative Distances from the Sun

1.     Complete Data Table B

a.    Research and fill in the mean distance from the sun (km) for each of the planets.

b.    Use the scale 25,000,000 km = 1cm to calculate the scale distance from the sun (cm).

c.    For answers less than 100 cm, round to the tenths place.

d.    For answers greater than 100 cm round to the nearest meter.

2.    Obtain a piece of chart paper that is about 10 cm longer than the distance from the Sun to Neptune.

3.    Measure a distance of about 2 cm from the end of the chart paper and mark it with an X.  Label this X- SUN.  This will represent the sun and you will measure all distances from this point.

4.    Using a meter stick/metric ruler, measure, mark and label the distance of each planet from the Sun’s reference point.

5.    Glue your planet circles from Procedure A onto the appropriate distance from the sun.

6.    Complete the discussion questions and conclusions.

Data Table B- Relative Distances from the Sun

Discussion Questions: Use your lab and your Planet Guides to answer the following questions in complete sentences or show your calculations. 

1. Which are the two largest planets?

2. Which planet is closest in size to Earth?

3. How do you the sizes of the inner planets compare to the sizes of the gas giants?

4. Jupiter’s diameter is how many times greater than Earth’s diameter?

5. The sun has a diameter of 1,394,000 km.  Using the scale from Procedure A, what would be the scale diameter for the circle representing the sun? Show your work!

6. Which planet has the shortest day?  Which planet has the longest day?  How do you know?

7. On which planet would you weigh the most?  The least?  Why?

8. Would your mass change if you traveled from planet to planet?  Why?

9. How do the distances between the inner planets compare with the distances between the outer planets?

10. Which two planets are closest to Earth?

11. Find the average distance of Pluto from the Sun.  Using the same scale as Procedure B, calculate the scaled distance that Pluto should be on your model. Show your work!

12. What happened to Pluto in 2006?  Why did this happen?

13. The next nearest star in our Milky Way Galaxy is Alpha Centauri.  It is about 41,000,000,000,000 km.  Using the scale from Procedure B, calculate how far Alpha Centauri would be on our scale. Show your work!

14. How do the densities of the planets change as you travel from Mercury to Neptune? What is special about Saturn’s density?

15. Calculate your age in Earth days/years on Mercury. Would you be older or younger on this planet?

16. Calculate your age in Earth days/years on Neptune. Would you be older or younger on this planet?

Conclusions:

Use your lab, research, and the article ‘Pity Poor Pluto’ as evidence in your conclusion. Analyze and summarize the following ideas on separate paper: 

• What did you learn about the size of the planets compared to each other and the sun?
• What did you learn about the distances the planets are from the sun?
• What did you realize about the distance to the next closest star?
• Describe the similarities and differences between the inner and outer planets.
• How do we now define a planet?  Why is Pluto now a dwarf planet?