Back when my oldest wanted to learn about the solar system for the first time, I obviously thought we should make a little model. Once I actually got a closer look at all those kits they sell in craft stores and elsewhere, I was disappointed. There was never any sort of consistent scale. For example, in most kits Jupiter is bigger than Earth, but sometimes, not by much. In some kits the sun was even smaller than Jupiter.
Now, I know making a scale model solar system is hard, but I felt so many of these kits would be misleading to young kids who don't realize how different these packaged solar system kits are from reality. They just don't do justice to the vastness and the amazing sizes they way they should. They certainly don't do much to inspire awe and wonder of the natural universe.
Thanks to Google, I was able to find this wonderful website for making your own scale model solar system:
You can plug in a size (the diameter) for the Sun you want to make, then it will tell you what the diameter each of the planets should be, and their orbital distance from the Sun. Your sun will need to be big if you don't want tiny dots for planets. We were going to use a hula hoop, but ended up just making a big circle with a piece of cord so we could have bigger planets. That way, our Jupiter came out to be about the size of a Frisbee, and we then measured and cut the other planets out of paper. Then we taped the planets to sticks so they would stick up out of the ground as we placed them in their orbits.
This is one caveat of the scale model solar system - Keeping the size of the planets in scale isn't too hard, nor is keeping the orbital distance, but doing both at the same time can be very tough. For example - in our model where the Sun had a diameter of 46 inches, and our Earth's diameter came out just under a half inch, if we kept the orbital distances consistent with that scale, Pluto would have to be over 16,000 feet away from our Sun. So we ended up with two scales, one for planet size, and another for orbits. The kids looked at the numbers with me, so they sort of knew that we were changing things from what they really should be.
Still, we found the biggest park we could, and laid out our circle for the Sun, then measured off the distances to stick our planets in the right places. Even though we had to plug in different numbers until we had Pluto no more than 50 or so feet away, the final model was very impressive, and illustrated much better the amount of 'space' in the Solar System.
It was a very fun and educational afternoon for us all. I am actually looking forward to doing it all over again in a year or so for the younger kiddo. She helped the first time, but she was so little, I don't think she could appreciate it yet. It really isn't as much work as it sounds like, with the help of the calculator at the Exploratorium website linked above. It is a very worthwhile activity.