This poster is designed to be used as an educational tool in your classroom to show your students what lies in the Universe beyond the surface of our Earth. It has been drawn in such a way that the sizes of the object shown are not to scale (or, that the sizes of the objects are not correctly sized relative to one another). Instead, we have given a scale that shows where objects in our Universe are based on distance.
This distance scale is called a logarithmic scale. This means that with each step on our scale (seen at the side of the poster) everything is 10 times larger than it was at the previous step. Think of it like a zoom button, where with each step, we’re zooming out. To give an example, if we start by looking at a person, the next step on the log scale would be something about the size of a building, and then of a street block, and then of a whole city... This is exactly what we’re doing in looking at our universe. We start with the earth, which is much much smaller than anything else on the poster, even though it looks the biggest. Then, by zooming out, we can see our solar system, then our galaxy, and so on.
It is important that you get this point across to your students. It may be very hard for them to understand. However, remember that the poster is for understanding what is in the universe, and how far away things are. Use the scaling to explain the vastness of our universe by explaining the concept of a light-year. Reinforce that objects are not sized proportionally, and give them examples of how things are really sized. (For example, if the sun was a basketball, the Earth would be an apple seed.)
To accompany the poster, consider incorporating a “known log scaling”:
This gives the teacher and students an idea of what a log scale is, and they can visualize how it works with things they know...Also to accompany poster, show SIZE SCALING of solar system.
Based on: http://www.astro.princeton.edu/universe/