Today my kids and I put together a safe solar observatory!
1 longish lens, like a telephoto camera lens, a binocular lens, telescope, or spotting scope.
1 carboard box the size of an orange box
1 9X12 sheet of white paper
1 tripod (optional)
It ended up looking SOMETHING like this:
At least you get the idea. We kind of combined the cardboard collar and the projector screen into one contraption by cutting a hole large enough for the lens to rest in at one end of the box, then taping the paper onto the opposite end of the inside of the box. This allows for a much more easily observed image, because the projected image is always in the shade and always directly opposite the lens, avoiding any problems with image distortion.
We were so excited at the prospect of seeing sunspots.
Unfortunately, there has been NO sunspot activity since December and a minimum of sunspot activity for the past year. In fact, 2008 has been called the 'blankest' sunspot year since the dawn of the space age. Any 'sunspots' we saw turned out to be dust on the lens--you can test whether the spots are dust by twisting the lens in the hole. If they move, they're dust.
Remember: NEVER LOOK DIRECTLY AT THE SUN--ESPECIALLY THROUGH A LENS!
Anyway, by the time my youngest is in high school, we should be able to observe sunspots with our observatory. For now, it's just COOL!!!