How to check if eclipse glasses are safe?

Question

With the solar eclipse coming on August 1st, and eclipse glasses being sold from sources that may or may not be reputable (and no alternative available), how can I check that the glasses being sold are safe to use during the eclipse?

For example, if I look through at the sun now (no eclipse) how bright should it be? How do I know it's safe?

(Is there a website dealing with this?)

Answer 1

If you don't know exactly where they came from, the answer is No. Think of what you are risking.

There are always alternatives. Fully exposed black and white film was the standard for a long time. A pinhole camera is idiot-proof.

Just looking through a filter won't prove anything, because this won't tell if you what the filter is doing to infrared.

Answer 2

One way is by experiment.  It's easy.  When you get your new solar glasses, look at the Sun.  If you go blind, then you'll know they weren't any good.

Siriusly, they are a thin film.  Every time you use them, you should check for pin hole defects.

Some years ago, there was a partial solar eclipse on Christmas Eve.  Astronomy Magazine put solar glasses in the magazine.  I used them to see the Moon blot out part of the Sun.  The light was a little bright, and it made me uncomfortable.  So i didn't look for very long.  There was no permanent damage.  These days, i use a full aperture solar filter for my telescope.  At low power, the full disk of the Sun (or the Moon) fills the field of view.  This filter is designed for my scope.  I check it for damage before using it every time.  It has been great.

Answer 3

Unfortunately, no eclipse glasses have been effectively been proven safe! For brief viewing they can be acceptable (you are still taking a risk, albeit a small one), but for extended looks at a partial eclipse phase (and who can resist!), a pinhole projector is the only easy solution.

Punch a small hole in a piece of card, and then project the sun's image onto another card or the ground. You will see a wonderfully formed sharp image of the sun.

Answer 4

the eclipse will not be visible from the United States except for a very small area in northern Maine

http://www.exploratorium.edu/eclipse/200...