I made a poor man's (or a poor woman's) real-life version of the inner solar system, using cotton balls, peas and a "home-made" table cloth.
I started off by using my very poor math and some googling to figure out the relative sizes and distances between the Sun, Mercury, Venus, the Earth and Mars. I decided that I could approximate the relative sizes of the Earth and the Sun as 2 centimeters (0.02 meters) and 2 meters, and I could also approximate the distance between them as 200 meters. Nice!
I also decided that I could approximate the distance between Mars and the Sun as 300 meters.
Finding a 2 centimeter diameter blue ball for Earth wasn't hard. I just went to the the supply room of my school and helped myself to some cotton balls (the school keeps them for the students whose future job will be to take care of and play with children). I took a blue one for the Earth, a white one for Venus (yes, the school has white ones, too) and a red one for Mars. I cheated and decided I would pretend that Mars is comparable to Earth and Venus in size. (Actually I sort of started from the cotton balls, and because they were 2 centimeters in diameter, not 1.5 centimeters, I had to scale everything up from about 1.5 (like the ~150 million kilometer distance between the Earth and the Sun, the ~13 thousand kilometer diameter Earth and the ~14 million kilometer diameter Sun) to 2.)
What about the Moon and Mercury? I couldn't pretend that they
were the same size as the Earth and Venus, so I bought myself some yellow peas. They had to stand in for the Moon and Mercury.
But getting myself a huge two-meter-in-diameter beach ball for the Sun proved too hard. If by any chance I had found one, I wouldn't have been able to handle it. And it would have been brightly colored
in a way that would just confuse people.
So I ended up buying some yellow fabric for the Sun. (Of course it shouldn't have been yellow, but white, but the white color would also have confused people. I cheated, took the easy way out, and settled for yellow.) I then asked a teacher at my school who teaches textile design to sew a round yellow table cloth, two meters in diameter, of the fabric. She did it for me. The 2 meter yellow table cloth would serve just fine as the Sun, if two people held it up for me.
I had calculated the distances to Mercury, Venus, the Earth and Mars, as well as the distance between the Earth and the Moon. (The latter was about 60 centimeters, 0.6 meters, if I remember correctly.) The distance from the Sun to Mercury was about 80 meters, while the distance to Venus was about 140 meters, the Earth was 200 meters away and Mars 300. I just stepped the distances to get the "planets" in the correct position from the "Sun". I think I did fairly well, because the "Sun" looked really quite right in size from a distance of 200 meters!
The guys in today's APOD did a truly great job with their real-life model, and the video is a very fine and instructive APOD!