Thursday, January 14, 2010

Solar Viewing Safety

I have had a few inquiries asking for details about safely viewing the sun, so I will summarize below.

For the full details see NASA's Fred Espenak Mr. Eclipse page.

There are 2 basic safe ways to view the sun (it does not matter if it is partially eclipsed or not).

1) Projection method.
    This involves using some kind of lens to project an image of the sun onto another surface.The simplest "lens" is just a pinhole. You can easilly make a pinhole in a piece of cardboard,
    Photo: Use Your Handsor even just use your fingers!

    2) Filter method
      You will need filter especially made for viewing the sun.

      You can get these in Israel or online. E.g.
      You can also use a number 14 (or better)  welders glass. These are available locally in many hardware stores.

      Here is a quick and easy projection method from the Exploratorium.

      How-To Images
      (Click on the image for expanded instructions)
      If you want, you can use only two pieces of cardboard--one piece colored white to project on to, and the other with a pinhole. Hold up the pinhole as far from the screen as you can. Remember, the farther you are from the screen, the bigger your image.
      Photo:Tree ShadowsPhoto: Use Your HandsGetting even more basic, you can use your own hands. Just hold up both hands with your fingers overlapping at right angles. The holes between your fingers make pinholes.
      If you have some shade trees in your location, try looking at the images of the sun coming through the holes formed by the leaves. A piece of white posterboard is all you may need to have a great viewing session!

      Or if you have a simple pair of binoculars you can these instructions from NASA:

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