People who plan to view the solar eclipse should check the safety authenticity of viewing glasses to ensure they meet basic safety standards, NASA has recommended.
A total solar eclipse, which is when the Moon completely covers the Sun, will occur across 14 states in the continental US on August 21, along with a 112 km-wide swath of the country.
More than 300 million people in the US potentially could directly view the solar eclipse, and NASA wants everyone who will witness this celestial phenomenon to do so safely.
This image of the moon crossing in front of the sun was captured on Jan. 30, 2014, by NASA's Solar Dynamics Observatory observing an eclipse from its vantage point in space. Credits: NASA
"It's common sense not to stare directly at the Sun with your naked eyes or risk damaging your vision, and that advice holds true for a partially eclipsed Sun," NASA said in a statement on Friday.
"But, only with special-purpose solar filters, such as eclipse glasses or a handheld solar viewer, you can safely look directly at the Sun," the statement added.
Eclipse viewing glasses and handheld solar viewers should meet all the criteria such as they should have certification information with a designated ISO 12312-2 international standard, have the manufacturer's name and address printed on the product, not be used if they are older than three years, or have scratched or wrinkled lenses, not use homemade filters
Ordinary sunglasses -- even very dark ones -- should not be used as a replacement for eclipse viewing glasses or handheld solar viewers
"While NASA isn't trying to be the eclipse safety glasses 'police,' it's our duty to inform the public about safe ways to view what should be a spectacular sky show for the entire continental US," said Alex Young, Associate Director at NASA's Goddard Space Flight Centre in Greenbelt, Maryland.
"It's important that individuals take the responsibility to check they have the proper solar eclipse viewing glasses. With the eclipse a month away today, it's prudent to practice ahead of time," Young added.
An alternative method for safe viewing of the partially-eclipsed Sun is with a pinhole projector.
In addition, the space agency has coordinated with medical and science professionals to provide additional safety information to the public.