A few years ago during my high school physics class, we learned about planetary orbits and how planets and stars are attracted to each other because of how gravity warps space. To illustrate this to the class, my teacher used a piece of stretched fabric to represent the "fabric of space" and used marbles of different sizes to represent planets and stars.
Though a simple concept, many different circumstances can be recreated with this simple device. It is a perfect idea for a classroom lecture, a father son project, or just as an afternoon time-waster.
Step 1: Materials
You will need:
Circular frame 2ft to 5ft diameter
Stretchy fabric (enought to cover the frame)
Rope (or other method of attaching fabric)
First, you must find something to mount your space fabric on. You want something that is circular and hollow in the center so there is enough room for the fabric to stretch underneath the frame. A hula hoop would make a perfect frame. In my case, I used a large drum approximately 2ft in diameter. You can have a frame of any size, but I recommend using a diameter of 2ft - 5ft.
You will also need some stretchy fabric. Spandex and Lycra are two fabrics that work well for this, but any fabric that stretches will work. You should have enough to completely cover your frame with some overhang.
To secure the fabric, you could use glue, string, staples, or any other method that accommodates your frame. In my case, a simple piece of paracord allows the fabric to be tightened over the top of the drum.
You will also need some marbles and weights to use as your mock planets and stars.
Step 2: Attaching the Fabric
Drape the fabric over your frame, making sure to center it. If you are using glue or staples, pull your fabric slightly taut before attacking it to the frame.
If you are attaching the fabric with rope or string, using a slip knot is an easy way to hold the fabric tight while still allowing it to be removed. This also allows you to adjust the tightness of the fabric.
You can trim the fabric after you attach it, but it is not necessary.
Step 3: Experiments
With your finished Space Fabric, there is a myriad of simulations you can run. This video shows some sample experiments. Keep in mind, with the Space Fabric, friction will cause the marbles to slow down and eventually stop. In space, there is no friction or air resistance so the planets keep on orbiting.
Have fun and happy orbiting!