No doubt, this year’s solar eclipse has come and gone, and one made use of one’s sunglasses to have a look at it. But soon another one will follow a decade away in North America. In case you have purchased paper glasses to see the eclipse, you will certainly be wondering if you can reuse them again after a gap of seven years when next total solar eclipse occurs.
On April 8th, 2024, those interested in watching solar eclipses will be in a position to see the moon completely blocking the light of the sun along the path of complete blockage that will cut across northwards from Mazatian, Mexico onwards to Netherlands as well as Canada.
The question that arises is whether the solar eclipse glasses that have been purchased for the Aug 21 event will be useful for observing the 2024 solar eclipse. In case, the glasses are not ruptured or punctured or rather torn then one can definitely re-use them again. This has been stated by a NASA guideline which lays focus on viewing solar eclipse safely. There are newspaper glasses that have been produced which are globally recognized as being optically safe to use, keeping in line with International Organization for Standardization (ISO) 12312-2 which have been typically printed with a stern warning that they should be got rid of after 3 years.
How does improper viewing of eclipse affect eyes?
If one looks directly at the sun without the aid of proper optical protective glasses then one’s eyes can get permanently damaged. It is important that that the paper glasses display the ISO 12312-2 certification that is much safer to make use of during the eclipse. This is the view held by American Astronomical Society (AAS). If there are leaks and punctures as well as scratches then the eclipse rays can penetrate accidentally and affect one’s eyes. Over a period of time the normal wear and tear as well as environmental factors can affect the lenses and the paper eclipse glasses can tear or become loose. They may not be able to protect one’s eyes adequately.
It is indeed difficult to say whether a pair of individual glasses will hold on for seven years with wear and tear. People do store these glasses for future use but if one were to ask if after six years whether these eclipse glasses still hold good one has to observe then and cannot say yes for sure. It is advisable to buy new glasses each time an eclipse occurs to be safe about one’s eyes.
One has to comply with ISO certification and although APO has produced glasses for about 25 years it does display a printed recommendation that the glasses must not be used for more than three years.
It is but obvious that one has to be careful about the usage of eclipse glasses and it is advisable to use new ones as the older ones get obsolete. Do enjoy your solar eclipse watching, but with proper glasses so that you do not damage your eye permanently.