Solar System Lab

Background Information: If you look at the full moon and a golf ball they seem to be about the same size. They look about the same because they are at much different distances from you. For example, from Earth, the sun and moon appear to be about the same size because the moon is much closer to Earth than the sun is. A scale model may help you visualize the relative size of the planets and their relative distance from the sun.

8th grade Science Standards: c. Students know how to use astronomical units and light years as measures of distance between Sun, stars, and Earth. e. Students know the appearance, general composition, relative position and size, and motion of objects in the solar system, including planets, planetary satellites, comets, and asteroids.

Problem: How can you show the relative diameters and distances from the sun to the planets?

Materials: meter stick, paper, calculator, tape, scissors, compass, textbook

Procedure: 1. Calculate the scale diameter of the sun. The diameter of the sun is 110 times that of Earth. Tape, measure, and cut paper to create half of the scale sun and label it. Calculate the scale diameters of all the planets. Make the Earth's diameter about the same as your pencil's eraser or ½ cm. Hint: Multiply the scale diameter of the Earth times the diameter of the sun in relation to the Earth, do this for all the other planets. Calculate the actual diameters of each celestial body. Hint: Multiply Earth’s diameter by the diameter in relation to the earth.

2. Using the chart below, calculate the average distances, in Kilometers, each of the planets are from the sun. Hint: Multiply the Earth’s average distance from the sun times the Astronomical Unit. Calculate the scale distance from the sun. Hint: Multiply Earth’s scale distance times the A.U. Use a meter stick to mark the distances from the edge of the sun, in centimeters, on your paper to the location of the center of each planet. On the scale model, the Earth would actually be 5000 cm away from the sun but for the purpose of this lab we will make it only 5 cm away. Remember that every value you calculate for the scale model should actually be times 1000! Write the A.U unit on the paper in between planets and the number of KM.

3. Sketch the planets in the correct positions on your paper, taking into consideration their relative diameter and color. Label them. Label all the actual distances and diameters on your model from the textbook (p.553 & 563). You do not have to put Alpha Centauri (Nearest Star) on the model. Represent the asteroid belt with lots of little dots. Extra Credit: Write how many moons each planet has next to the planet and how many rings each planet has. Use the internet for the most accurate, up to date number of moons and rings).

Data Table:

Sun
and
Planets / Diameter in relation
to the Earth / Diameter
(Km) / Scale
Diameter
(cm) / Actual
Distance
(A.U.) / Average
Distance from the sun
(Km) / Scale
Distance
(cm)
Sun / 110 / -- / -- / --
Mercury / 0.4 / 0.4
Venus / ~1.0 / 0.7
Earth / 1.0 / 12,756 / 0.5 / 1.0 / 150,000,000 / 5

Moon

/ 0.25 / 1.002
Mars / 0.5 / 1.5
Asteroids / <0.07 / 2.8
Jupiter / 11.2 / 5.2
Saturn / 9.5 / 9.5
Uranus / 4.0 / 19.2
Neptune / 3.9 / 30.1
Pluto / 0.2 / 39.5
Nearest Star / 100 / 270,000

Consider that if you were traveling at the speed of light, it would take about 8 minutes to

travel from the Sun to the Earth (1 AU). It would take 4.3 years (traveling at the speed of

light - 300,000 kilometers per second) to reach the next nearest star, Alpha Centauri!

Questions:

1. What is an astronomical unit, (A.U.)? What is a light year?

2. Excluding Pluto, compare and contrast the four closest planets from the sun to the four farthest planets from the sun. Why were you asked to exclude Pluto?

3. Why do the planets orbit the sun?

4. Look at your values for the diameters and the distance and compare them to the textbook’s values. Why do you think they are not the same?

5. If you did the length to actual scale, how long would your model have been? In centimeters? In kilometers?

6. Why is Pluto no longer considered a planet? Which planet has an unusual rotation?

Conclusion: Write about what you learned from doing this activity.