Students will understand the scale of Solar System in terms of relatively well-known sizes and distances on Earth.
Solar System
city map
scale model
Students will understand the scale of Solar System in terms of relatively well-known sizes and distances on Earth.
The Solar System is home to a star located at its center and to eight planets including Earth. These planets orbit around the Sun and present variations in size and composition. The Solar System is located in the Milky Way galaxy along with a vast number of stars. The great distances between the stars are almost unimaginable along with the location of the Solar System in the Universe. Compared to these distances, the planets of the Solar System are close, but compared to distances on Earth, it becomes difficult to visualize them. The distance between Pluto and the Sun is about 5.9 billion kilometers!
Sun and planets in the solar system: (teachers are encouraged to share these information while conducting the activity)
The Sun is the closest star to Earth consisting of electrically charged particles and mostly composed of hydrogen and helium. More than one million Earths could fit into it. The Sun is a middle sized star powered by nuclear fusion. It takes about 8 minutes for the sunlight to reach Earth after being emitted from its surface.
Mercury is the nearest planet to the Sun and also the smallest in size. Since the planet lacks of an atmosphere, it experiences both hot and cold extreme temperatures. Out of all the terrestrial planets in the Solar System, Mercury is the densest planet.
Venus is the hottest planet of the Solar System and is very close in size to Earth. The planet possesses a very dense atmosphere of mainly carbon dioxide that causes it to reach the highest temperatures of all the planets (740 Kelvins at the surface while Earth is about 290 Kelvins!). Venus is nearly covered by a thick layer of sulphuric acid clouds that prevent the solar rays to penetrate in the atmosphere below.
Earth is the only planet known so far to support life. It has a magnetic field that extends thousands of kilometers into space and protects the planet from harmful incoming solar radiation. The planet is located at the center of what astronomers call the habitable zone, where temperatures are suitable enough for water to exist in its liquid state.
Mars presents frozen water in its polar caps. Several flybys, landers, orbiters, and rovers have been sent to Mars to study the planet. However, one of the biggest questions about the planet still remains open: did water ever exist on Mars?
Jupiter is the largest planet of the Solar System and is the first among the gaseous planets. It contains more than twice the mass of all the planets of the Solar System together. The planet is so large enough that 1400 Earths can fit into it.
Saturn is well known for its bright rings. Saturn needs about 30 Earth years to orbit the Sun but only about 11 hours to rotate around its axis. Its rings are composed of billions of icy and rocky materials.
Uranus is known as an ice giant planet since is composed of relatively great amounts icy methane and water. Uranus rotation axis is tilted almost parallel to its orbital plane while the rest of the planets spin more or less perpendicular to the plane of the Solar System.
Neptune is the most distant planet of the Solar System. It is roughly half as far from Uranus as Uranus is from the Sun. Like Uranus, Neptune has rings that are thin and which consequently appear very dim when observed.
Other bodies: * The Moon is Earth's only natural satellite and it was visited for the first time by the Apollo 11 landing mission in 1969. The dark and relatively featureless lunar areas that can be clearly seen with the naked eye are called maria, which are known to be the result of ancient balsatic lava.
The asteroid belt is a region of the Solar System found between the orbits of Mars and Jupiter and it is occupied by asteroids of different shapes and sizes. Asteroids are rocky-metallic objects which are also called planetoids or minor planets because they are too small (they can range from the size of pebbles to ~ 1000 km).
Comets are icy small bodies that have a wide range of orbital periods. When passing close to the Sun, comets heat up and outgas material giving it the shape of a snowball with a tail. They are known to have a wide range of orbital periods.
Pluto is a dwarf planet found in the Solar System. Since its discovery in 1930, Pluto remained classified as a planet until the detection of the more massive body Eris put it in question. In 2006, the definiton of a planet stated by the International Astronomical Union excluded Pluto since it failed to clear out the neighbourhood objects from its orbit.
Astronomical unit (au): Is a unit of length, approximately the distance between the Earth and the Sun, astronomers use to describe the great distances in the Solar System.
The scale factor:
In a scale model, all linear distances and sizes are enlarged or reduced by a scaling factor. The scale factor is given by; scale factor = true value/reference value
For example, when scaling the Solar System, the diameter of Earth and the reference size (in this case is a peppercorn of 2 mm) could be used as the true and reference values, respectively. In order to scale the rest of the planets, their true sizes and the scale factor calculated above are used:
scale model = true value/scale factor
Example of a scaled model of the Solar System on the city map of Munich showing the orbits of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune around the Sun (located at the city center in Marienplatz, Munich, Germany).
The activity consists of engaging students to build a reduced-scale model of the Solar System. It is very difficult to visualize the great empty space that exists between the planets and the Sun and to realize how big or small these are relative to each other. The following steps may help in the realization of the scale model:
Involve students in an introductory discussion about the Solar System:
Engage students in predicting the model:
By the end of this step, students should be able to understand that both distance and size are required to build a scale model.
Have students build a scale model based on calculations
Let students build a scale model on a city map and extend to other scenarios
Organize a walk with students to the different locations of the Solar System bodies on a city map * Motivate students to go on a journey through the Solar System. * Hand the Sun and the planets to students before starting the walk. * Make sure most students are more or less familiarized with the locations placed on the map. * Feel free to separate students into different groups to represent each body and stand on their location while the rest reach the next. This step depends on the city type you are located and it is more suitable on a long straight street. * When reaching to the different locations, ask students facts and characteristics about each of the bodies. Relate the planets' orbital periods to their distances to the Sun (the further away they are, the larger the orbital period).
Questions for the instructor to ask themselves to evaluate the student learning:
Country | Level | Subject | Exam Board | Section --- | --- | --- | --- UK | KS3 | Maths | - | Ratio, proportion and rates of change: scale factors UK | GCSE | Maths | AQA | 3.3 Ratio, proportion and rates of change: R2, R12 scale factors UK | GCSE | Maths | Edexcel | 3.3 Ratio, proportion and rates of change: R2 scale factors UK | GCSE | Maths | OCR | 10. Mensuration .01c) Maps and scale drawings UK | GCSE | Maths and Numeracy | WJEC | All tiers: Geometry and Measure: scale drawings UK | GCSE | Physics | Edexcel | 3. Waves and the Universe .4 Sizes and Distances UK | GCSE | Physics | OCR A | P1 The Earth in the Universe P1.1.6. UK | GCSE | Physics | OCR B | P2f) Exploring our solar system UK | GCSE | Physics | WJEC | Physics 1.7 The Solar System and its Place in an Evolving Universe a) UK | GCSE | Astronomy | Edexcel | 2.1 Our Solar System c
The activity should help students understanding the great distances between Solar System bodies and their relative size. It should provide a sense on how a scale model is built and its relevance to visualize the Solar System around their city. Students should reflect on how the model changes if only a single characteristic of the celestial body is taken into account in the calculations.