The Earth is part of a system of planets orbiting around a star (the sun) (1) identifying the planets of the solar system and comparing how long they take to orbit the sun (2) modelling the relative size of and distance between Earth, other planets in the solar system and the sun (3) recognising the role of the sun as a provider of energy for the Earth. (ACSSU078)A previously released resource, Solar System Happy Families (see previous post), may also be of interest.
‘The Hitchhikers Guide to the Galaxy’ says it beautifully
“Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mind bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space, listen...”But to grasp ‘how big’ requires us to play around with the scale of the objects in a system. Because of the difference in magnitude of the planet’s size and the distances between them it is not possible to represent both in a diagram. At best we need to use two scales, one for the planetary size and another for the distances between the planets. Certainly any representation of the orbits of the planets that would fit in a book would have planets so infinitesimal as to be invisible if distance and size were the same scale.
To grasp both we can conceptualise the Solar System with scaled objects and then place them in the landscape, either in reality (using a walk or a drive) or imaginatively (using maps). Such representations are a common science outreach tool. For example, the Solar System Drive in NSW, is scaled so that the 37m dome of the Siding Springs observatory represents the sun.
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| The Neptune station on the Solar System Drive, NSW. A pull over point on the Newell Highway. |
Deeper learning can be achieved if students work on representations based on their own imagining. Solar System Rescaler (link here) provides an online rescaling tool to achieve this. Based on simple formulas, first written in Excel and now transferred to Google Sheets, the spreadsheet enables a user to enter the dimensions of an everyday object to represent one object in the solar system, for example, what if the Earth were the size of a marble? The spreadsheet then calculates a scaling factor and rescales both the orbits and the object sizes of a number of nominated objects in the solar system. Instructions and explanation of the formulas is provided in the supporting documentation linked to via the rescaler.
A couple of examples.
In my backyard I created a representation of the Solar System rescaled so that a 400mm bird bath could represent the sun. Only the four inner rocky planets would fit inside my yard and I represented these with holes drilled into aluminium plates that I attached to the fence, thus the Earth was 3.6 mm in diameter and 42.8 m away from the bird bath. The furthest planet, Neptune, was 1.29 km away. Amazingly at this scale, the nearest star, Alpha Proxima at 4 light years away would be represented as being 10,800 km distant from my bird bath. And what is between us and our nearest star? Well… billions of tiny objects which are so small that on average we could consider the space as ‘empty’. That is our nearest star! The furthest object visible to the unaided eye is 2.25 million light years away. Space is big!
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| Aluminium plate for Mars, planet size represented by the hole with orbit of the two moons, Phobos and Deimos, represented by scribed circles. |
Lego produced planets for some of their Star Wars models and I like to play around with these in the classroom. In part because Lego is a familiar object, and for many students is immediately associated with creativity, but also because it is big enough to allow for tactile engagement.
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| Lego planet element and Lego boulder, with an Australian fifty cent piece for scale. |
I start with these two objects a Lego planet, representing earth, and a Lego boulder, representing the moon (the scaling is about right). Invite students to hold the two objects, estimating what they consider to be the correct distance apart to represent the moon’s orbit. Most will nominate a distance under 600mm. The true distance is closer to 2.6m. Below is the output from the rescaler.
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| Screen grab from the Rescaler. Note the entry of the planet’s size, 86 mm, in the rescaler column. Also note that the object type filter is active and displays only planets, the sun and the moon. |
It is then possible to ask the question, what if we scaled the Solar System so that the sun was the size of the Lego planet? Segueing from this I produced a postcard resource (link here) which encourages students to decorate a postcard for a Lego representation of the Solar System, asking the question, how big would the Solar System be if any planet were scaled to the size of the Lego element?
Students then research various metrics for the planets, daylength, orbital period, max and min temperature, number of satellites etc, etc. This information could then be recorded on the card.
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| Postcard for Jupiter. On the left is a blank lego planet (full size) for students to decorate. On the right the planets name, planetary symbol and a 1:1,000,000,000 dot to represent the planet at that scale. |
Suggested extension activities for the postcards include.
a) Having conducted the research into another planet, students could write an imaginative piece pretending they were on that planet and writing a postcard to a friend either on Earth or on another planet in the Solar System.
b) When Lego released the planet element, it was Star Wars themed. Students could design a Lego build to go inside the planet element, together with an appropriate mini figure that could represent someone who may have been of influence in learning about the planet, or perhaps the god after whom the planet is named.
c) The postcards contain a scaled version of the Solar system (1 is to 1 billion) in the right panel of the card. Students could lay these out around the school grounds and perhaps share their learning with another class who is not working on the unit.
If you invent other things to do with this please share - use the comments section below.
