Solar Viewing Tube
by
Dr. James N. Pierce
Emeritus Professor of Astronomy at
Minnesota State University, Mankato
This is a good, safe way to view the Sun, during an eclipse, a transit, or anytime. And you can make it yourself!
Construction
- Get a long cardboard tube, such as a gift wrap tube. (A long box will do — it need not be round.)
- Cover one end with aluminum foil, dark tape, or some other opaque material, and make a pinhole in it.
- Near the other end, cut a viewing port in the side of the tube.
- Cover this end — but not the port — with white cardboard to make a screen at the end of the tube.
Observation
- Try it out! Stand with your back to the Sun. (Do not look at the Sun!)
- Hold the port end in one hand and rest the foil end on your shoulder (like a soldier on parade).
- Now for the tricky part: Move your hand until the sunlight shines directly down the tube such that the Sun’s image appears on the white cardboard screen as seen thru the viewing port.
- Note: When this occurs, the shadow cast by the tube will be minimized.
- You may find it more convenient to mount your solar tube to a tripod, as shown here.
Long Tom:
Construction Variables
- More holes yield more images.
- Bigger holes let in more light and produce brighter — but somewhat fuzzier — images.
- Longer tubes make bigger images; image diameter is about 1/10 inch per foot of tube length.
- Wider tubes are easier to point, due to the larger screen.
A Two-Holer:
