In our February 22 blog, we reviewed various methods of safely viewing the Sun during its partial phases of eclipse. One of these is by use of solar glasses (also called solar viewing glasses) that are simple to use, safe, and inexpensive.
Solar glasses usually consist of cardboard frames (more expensive ones are made of sturdier plastic) that hold a Mylar or, more typically, black polymer material that filters out harmful solar rays.
The International Organization of Standardization (ISO)—a worldwide body that sets standards for commercial and industrial products and processes—addresses safe viewing of the Sun in the
ISO 12312-2 standard (this is often listed more specifically as ISO 12312-2:2015). For solar eclipse glasses to be certified under this benchmark, they must block ultraviolet and infrared light as well as reduce visible light to safe and comfortable levels.
“If solar eclipse glasses are not marked as meeting the ISO standard, you’re better off not using them.”
Glasses that meet this standard should be marked as such (something like “Meets the requirement for ISO 12312-2:2015”). Safety is paramount with solar viewing, so if solar glasses are not marked as such, you’re better off not using them.
Rainbow Symphony is one company that has certified its solar glasses meet the ISO standard. This California-based manufacturer of 3D, eclipse, diffraction, and other varieties of glasses has produced the solar eclipse glasses that all participants at the Lowell Observatory Solar Experience will receive.
By Kevin Schindler, Lowell Observatory Historian