Update: NASA's website includes a fifth company under certain conditions. This article is updated to include that.
NASA is warning unsafe eclipse glasses are being sold to consumers.
A total solar eclipse crosses the United States on August 21. Far west Kentucky is in the path of totality - and most of the North American continent will experience at least a partial eclipse.
Special eye protection is required for safe viewing. More about eyeglass safety.
NASA is recommending using only glasses with ISO 12312-2 printed on them and that are produced by one of four companies: American Paper Optics, Rainbow Symphony, Thousand Oaks Optical and TSE 17.
Their safety website also includes Baader Planetarium, but only the AstroSolar Silver/Gold film glasses.
According to NASA, these are the five manufacturers that have certified their glasses meet that ISO numerical standard.
NASA also says not to use glasses older than three years.
This article has been updated - and may be updated in the future.
