How to make your own sunspotter

The general idea of the design is that you want to have a surface that is parallel to the plane of the equator, and the scope rotates in this plane to 'undo' the rotation of the earth. This way you only have one knob to deal with as you are trying to keep the sun exactly on target. Since the earth's axis is tilted 23° relative to the normal of the orbital plane, you need to be able to adjust the elevation of the scope relative to this equatorial plane by only + or - 23°. This is why this mount is simpler than a mount for a regular telescope, where you'd want to be able to adjust this angle all the way to +-180°.

With this thing you can make daily sunspot observations, and record them on standard index cards. After a few days, you have a flip-book where you can see the sunspots running around the sun's surface. It is easy enough to do for 4th graders. Everyone gets to keep their observations. For full details, see this page.

In the picture above, the big disk rides on a tilted surface, and you follow the sun by slowly turning the handwheel on the right. The wheel turns the threaded rod, which moves to the left or right the little clamping piece that grabs the bottom of the disk, and thus rotates the disk. There is a counterpart clamping piece on the top of the disk, where a knob allows you to loosen the clamp, turn the disk for gross adjustment, and then reclamp it.

The elevation gross adjustment sits on top of the disk, and the elevation fine adjustment is a knob underneath the front of the scope. An image of the sun is projected onto a standard 3.5×5 index card, held by the cardholder.

Since the instructions have lots of pictures, I broke them up into a few separate pages. All measurements are in inches (with apologies to people who live in the real world).
Here goes:  
  1. Base assembly
  2. Main disk and clamp
  3. Scope support
  4. Elevation fine adjust
  5. Shopping list

      Last update 9 Jan 2002