With Christmas coming I wanted to build an homemade gift for my parents, and because they love watching stars and planets, I decided to build a solar system they could control switching ON and OFF each planet of the solar system.

For an overview of the project, watch the video below:

And if you liked it, you can read the details of this article to see how I made it!

Step 1: The Fluffy Planets

At first I have made the planets and the sun.

Why fluffy planets? I did not wanted too smooth planets, plus I wanted something that could hide the LEDs in it but that could make the light pass through too. So I made them as follow:

Materials:

-transparent christmas balls of different sizes:

The biggest for the sun
2 big balls for Jupiter & Saturn
2 medium balls for Uranus & Neptune
2 small balls for Venus & the Earth
2 very small balls for Mercury & Mars
And a tiny one for the Moon!

-transparent double sided tape

It needs to be transparents to let the light pass through

-cotton

Method:

Then it is quite easy to do the rest, just stick the double sided tape on the christmas balls and add the cotton on it, and remove the excess (a thin layer of cotton is enough).

Note:

At first I wanted to paint the cotton of each planet... But once the system was finished and before to paint them, I found out that it was more beautiful and kind of magic to have all the white planets getting coloured when the light is switched on. So I did not paint them!

Step 2: The Structure

An easy way to make the structure of the solar system was to use PVC pipes. It is cheap, easy to cut, light, and nowadays there are PVC glues that works great.

Materials:

-16mm Ø PVC pipes

They have to be pipes because some wires are going pass in these pipes

-100mm Ø PVC piece

I do not know how it is called, but when I saw it in the shop I decided it would fit to this project

-8 16mm Ø PVC fittings

-PVC glue

Method:

The first step was to drill the 100mm Ø piece (make 8 hole for the fittings; 1 fitting for 1 planet), then glue the fittings in each hole. The result is something that looks like a spider, so I will call it "the plastic spider" for the next steps.

Then I have cut 8 PVC pipes of the same size (something like 80 cm long) & drilled small holes for the wires connected to the planets (something like 2mm Ø holes) at different distances according to the planets they are connected to.

For example:

Mercury is the first planet, I made a hole on a first PVC pipe at 10cm from an edge of the pipe (and 70cm from the other...)
Venus is the second, made a hole at 20 cm
The Earth is the third, 30 cm
...
Neptune is the 8th, 80 cm

I also made some holes in the plastic spider:

One below for the wire connected to the sun
One above for the power supply
Another one above for the controller

I have fixed a hook on the top of the spider so it is easier to hang.

To finish I have painted it in black using a coating first to make the paint stick properly to the PVC.

Step 3: The Light and the Power Supply

Materials:

-a power supply

As a power supply I have used an old printer adaptor with 32V and 1560mA. That is enough for several LEDs in series and in parallel.

-LEDs

-resistors

Method:

I bought white LEDs, and I have soldered 5 LEDs in series with an adapted resitor (remember U=RI). As each LED has a forward voltage of 3V, I could add at least 10 LEDs in series (32/3=10,6). I made this 8 times (5 LEDs for each planet) + 2 more for the sun because I wanted it to be brighter than the planets, and everything goes now in parallel. As each LED has a forward current of 20mA, I could add at least 78 LEDs in parallel (1560/20=78).
I have also cut the top of the LEDs to make the light diverge
Then to color the planets I have used coloured transparent papers. It has the advantage to be really cheap (for less than 3 euros), and using differently coloured sheets I could have a wide variety of colors.
- For Mercury I have used a yellow and a brown sheet
- For Venus yellow and red
- For the Earth just blue
- For Mars just red
- For Jupiter two brown sheets
- For Saturn just one brown sheet
- For Uranus blue and green
- For Neptune blue and red

At first I wanted to paint the christmas balls, but the paint was much more expensive... Also a more elegant way to color the planet would be to use colored LEDs but it was easier for me to order white LEDs.

Step 4: The Wires and Connections

I have used USB cables for the wires. First because they are thin enough, but also because they are easy to buy and cheap, and they have 4 different wires (+, - and 2 data wires). But I have removed the USB plugs...

I have connected each 5-LEDs to a wire and added these wires in the PVC tubes to reach the plastic spider.

As I wanted something that was easy to carry, I have added connectors at the end of each cable. And in the plastic spider, I have made what I call an "electric spider", with the connectors (8 for the planets, and 2 for the sun). The - of each connector is connected to the - of the power supply cable that comes in the plastic spider, and the + of the connectors are connected to the + of the power supply.

Step 5: The Controller

To make it funnier, I decided to add a controller to switch ON and OFF the planets!

Materials:

-3 meters long USB cables

-a plastic box

I have used one that is commonly used to stock screws and nuts

-8 toggle switches (1 for 1 planet)

-photos of the planets

Method:

I have first made a 3 meters long cable (made of 2 USB cables=> so 8 wires for the input signal coming from each planet; and a simple wire to connect each planet to the - of the power supply)
Then I have soldered each input wire to a switch and all the output of the switches together
I have glued the photos on the plastic box
I have drilled it, and added the switches, making sure the switch below each planet control the right planet