As the April 8th total solar eclipse approaches, millions are preparing to witness the event from different parts of the United States.

The American Astronomical Society (AAS) is warning about the risks of counterfeit solar glasses and the importance of using safe viewers to protect your eyes.

“Filters that provide safe, comfortable views of the sun generally transmit between 1 part in 100,000 (0.001%) and 1 part in 2,000,000 (0.00005%) of its visible light,” says Rick Fienberg, Project Manager of the AAS Solar Eclipse Task Force and a veteran of 14 total solar eclipses. “Solar filters are at least 1,000 times darker than even the darkest regular sunglasses.”

To test your solar eclipse glasses, try them on indoors; you shouldn’t be able to see anything. Then, try them outside on a sunny day. They should still block out everything except the sun’s weak reflection off a glossy surface.

What are your solar eclipse plans?