What's the simplest way to view sunspots at home?

[wimms]

Is it possible, and what would be simplest means to view sunspots at home? I figured some projection on the wall would be nice, but what you'd need to a get sharp image of say 2ft diameter?

 

[branebrain]

Hi Wimm,

A very simple solar viewer is simply a small hole poked in a piece of cardboard. If you move the cardboard away from the surface it is projecting onto, you will see a focused image of the surface of the sun. Stray light makes it difficult to see much detail though so a box with a pin hole and a viewing hole might do the trick (you'll still not approach anything close to 2 feet in diameter, however ~6"). Probably the next best way would be to use a small refractor or reflector telescope and use eyepiece projection (CAUTION: NEVER LOOK DIRECTLY THROUGH THE TELESCOPE AT THE SUN), because the sun's light is gathered by the optics and can be projected a greater distance and subsequent magnification reveals greater detail. Still 2 feet is probably pressing it as far as useful detail is concerned, I'd stay with about 6-10" even with a small scope.

bb

 

[Phobos]

any risk to the optics of the telescope?

 

[ray b]

I use to do that with a survey transit/theodilite
mostly during eclipes but some times just to look at sun spots to project a 5 to 8 inch image of the solar disk on paper
never noticed any bad effects and the insterments were used daily for years in a controlled checked condisions of land surveying

 

[Rog]

Being a beginner amateur astonomer I have read a lot of stuff on the net about this and no one has posted anything regarding damage. You can also by sun filters which will reveal more detail on your projection from a telescope. Before you attempt anything with a scope and the sun, I would do some serious reading and preparation. As has been said before you are dealing with quite a bit of concentrated energy by viewing the sun in this way and anywhere near your eye means goodbye sight!

 

[Labguy]

Originally posted by Phobos
any risk to the optics of the telescope?

Many good eyepieces have one or more cemented elements (usually two at a time) and I have seen four destroyed in just one day of showing the public some sunspots (not MY scope). In cheaper scopes, the eyepiece housings just simply melt.

 

[branebrain]

Labguy,

Good point. I should have recommended simple projection without the eyepiece. If you have a goto telescope you can center and follow the sun projected onto a white card and damage can be avoided.

bb