Scale Model of the Solar System

Summary

Astronomy is one of the oldest science in the world. Stars and other heavenly objects have been studied for thousands of years by Humans. In the modern world, the fascination with space and astronomy has increased.

These activities will stimulate curiosity of students towards sciences by teaching them about astronomy and space in an interactive way so they understand that the universe is a large place with many wonders.

Materials:

- Meter stick
- Big outdoor space, at least 33 meters long.
- Paper
- Pencil
- Large glass or small bowl
- Scissors
- Black marker
- Different sizes spherical balloons (at least one should inflate to 22 cm diameter)
- Optional: Camera to make a permanent record of model.

** **

**Project Assumes students are familiar with:**

- The 8 planets and their shapes
- Length units, cm, m, km and numbers, like 1 million (1000000).
- Diameter of sphere or circle (if they don’t know, activity will help them understand)
- Ratios, comparisons of quantities

**Students will learn at the end of activity:**

- Planet: definition, number of planets and planet distances from the sun.
- Comparative distances of planets from the sun and their comparative sizes.
- Meaning lengths using meter rod or ruler.
- Definition of Astronomical unit.
- What is space?
- What makes planets held together? Gravity!
- Ratios
- Difference between circle and sphere

** **

**Introduction:**

A solar system is a group of planets and other space material orbiting (going around) a star. In our solar system, that star is better known as the Sun and the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

The solar system models we’ve seen before probably don’t show how much bigger some planets are than others, or, more importantly for space travel, how far away the planets are from the Sun and each other. The Earth is about 150 million kilometers (93 million miles) from the Sun. Because this distance is so important to us Earthlings, it has been given a special name, called the Astronomical Unit (A.U.) for short. The Earth is one astronomical unit from the sun. Planets that are closer to the Sun than the Earth have a measured distance of less than one A.U. while objects farther from the Sun than Earth have a measured distance of greater than one A.U.

The size of a planet can be determined from its diameter. Diameter, we remember from math class, is the distance from one end of circle or sphere to another side, going through the middle.

In this activity, we will make two scale models of the solar system. A scale model uses the same measurement ratios as the real object does.

- The first model will compare the distance the planets are from the sun in astronomical units,
- The other model will compare the size of the planets using diameters in kilometers. We probably won’t be able to display either of these models, but we will learn a lot about the real dimensions of space.

Problem

**How can we make a solar system scale model?**

**We want a model to reflect the relative distances and sizes of the planets.**

Materials:

- Meter stick
- Big outdoor space, at least 33 meters long.
- Hard paper (the one we use to make charts)
- Pencil and markets
- Large glass or small bowl
- Scissors
- Black marker
- Compasses
- Optional: Camera to make record of model.

Procedure: Scale Model of Distances from Sun

- Trace 9 circles using the bowl or compass as a guide or inflate balloons corresponding to the sizes of planets. Because the distance scale model only is concerned about distances between the planets, we can make all the planets the same size.
- Label the circles Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
- Cut the circles out.
- Give each of students a cut-out planet to hold.
- Have students position themselves the following distances from each other. (Note that some of the measurements are in centimeters rather than meters. A centimeter is 1/100 of a meter, just like a cent is 1/100 of a dollar).

Planet |
Distance AU |
Model Distance from “Sun” |

Mercury | .38 | 38 centimeters |

Venus | .72 | 72 centimeters |

Earth | 1.0 | 1.0 meter |

Mars | 1.5 | 1.5 meters |

Jupiter | 5.2 | 5.2 meters |

Saturn | 9.5 | 9.5 meters |

Uranus | 19.2 | 19.2 meters |

Neptune | 30.1 | 30.1 meters |

Materials:

- Metric ruler
- White poster board
- Pencil
- Drafting compass (the kind we draw circles with)
- Scissors
- Permanent Marker

Procedure: Scale Model of Relative Diameters of Planets

- First, we need to compare the diameter of the Earth to that of the other planets. Remember that diameter is the length of a straight line going through the middle of a circle. The Earth’s diameter is 12,760 km. We can divide the diameter of the Earth into the diameters of all the planets, to get a relative comparison.

Planet | Diameter in kilometers | Relative Diameter
Compared to Earth |
Size in cm/inches, so match up with apparatus we can multiply by a factor 2 or 3 |

Mercury | 4800 | .376 | .4 cm |

Venus | 12100 | .949 | .9 cm |

Earth | 12750 | 1.00 | 1 cm |

Mars | 6800 | .533 | .5 cm |

Jupiter | 142800 | 11.2 | 11 cm |

Saturn | 120660 | 9.46 | 9 cm |

Uranus | 51800 | 4.06 | 4 cm |

Neptune | 49500 | 3.88 | 3 cm |

- Use the ruler to draw a line for the diameter. Start with drawing the relative diameters of Jupiter, Saturn, Uranus and Neptune.
- Using the compass, draw circles around the diameters.
- Fit in the smaller planets (Earth, Mercury, Venus, and Mars) around where we drew the bigger planets.
- Label the planets, so we don’t forget which is which when we are cutting them out. For tiny planets, we might have to use an abbreviation.

Results

When we build the scale model of solar system distances, we notice following things:

- Some students will be much closer together than others. Some of their friends will have to stand quite close to each other, while others will be far enough away to have a hard time hearing us!
- When we compare the sizes of the planets, Jupiter and Saturn will seem gigantic compared to the others.
- We will see the solar system will be mostly empty, and even big planets make up a tiny part of our solar system.
- Sun and 8 planets line on same plane because of gravitational attraction.

Why?

The inner planets of the solar system; Mercury, Venus, Earth and Mars are relatively close to the Sun and each other, while the outer planets are relatively distant from each other and the Sun. The material that makes up the solar system is not distributed evenly. The Sun, Jupiter, Saturn, Uranus and Neptune make up the bulk of the material in the solar system. Our own planet is tiny in comparison!

Going Further

Do we want to make a scale model of the solar system where **both** the distances and diameters are proportional to reality? This table expresses the diameters in A.U, so the size of the planet is correct proportion to its distance from the sun. Remember we set 1 AU, the distance between the Earth and Sun, as equal to 1 meter.

Planet | Diameter in kilometers | Relative Diameter
In AU (meters) |

Mercury | 4800 | 3.2 x 10^{-5} |

Venus | 12100 | 8.1 x 10^{-5} |

Earth | 12750 | 8.5 x 10^{-5} |

Mars | 6800 | 4.5 x 10^{-5} |

Jupiter | 142800 | 9.5 x 10^{-4} |

Saturn | 120660 | 8.0 x 10^{-4} |

Uranus | 51800 | 3.5 x 10^{-4} |

Neptune | 49500 | 3.3 x 10^{-4} |

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