Protect your eyes while enjoying the spectacle of a total solar eclipse - CNN

The scintillating cosmic phenomenon of a total solar eclipse will be visible to millions of people across parts of Greenland, Iceland, northern Russia, Spain and Portugal on August 12.

It’s the first of three eclipses anticipated over Spain in the next two years. The best way to prepare for safe viewing of the stellar lineup is to locate a pair of eclipse glasses. Sunglasses won’t be enough to protect your eyes for direct viewing of the spectacle.

A total solar eclipse occurs when the moon passes between Earth and the sun, completely blocking the sun’s face. Since the total solar eclipse will occur over Spain in the evening, sky-gazers are in for a rare treat: a sunset eclipse in which they will see a crescent sun setting after the total solar eclipse.

Those in the path of totality, or locations where the moon’s shadow will completely cover the sun, will see a total solar eclipse. People outside the path of totality will be able to see a partial solar eclipse, where the moon only blocks part of the sun’s face. A partial eclipse will pass across the northern United States, Canada, much of Europe and northwestern Africa. Check Time and Date to see when it will occur in your area.

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If your location only affords a view of the partial solar eclipse, some of the sun’s powerful light will be visible throughout the event. And any glimpse of the sun’s brightness with the naked eye is not only uncomfortable but also dangerous.

Why you shouldn’t look directly at the eclipse

The only time it’s safe to view the sun without eye protection is during the totality of a total solar eclipse, or the brief moments when the moon completely blocks the light of the sun, according to NASA. Any hint that light is reappearing means it’s time for eye safety measures.

“Even the 1% of the Sun’s surface that remains visible emits enough radiation to permanently damage the eye’s light-sensitive cells,” according to the Institute of Astrophysics of the Canary Islands, which is located along the 2026 eclipse path.

Directly staring at the sun can result in blindness or disrupted vision. During the 2017 total solar eclipse, a young woman was diagnosed with solar retinopathy, retinal damage from exposure to solar radiation, in both eyes after viewing the eclipse with what doctors believe were eclipse glasses not held to proper safety standards.

There is no treatment for solar retinopathy. It can improve or worsen, but it is a permanent condition.

Using eclipse glasses and solar viewers

To view the eclipse, wear certified ISO 12312-2 compliant eclipse glasses or use a handheld solar viewer. Separately, you can observe the sun with a telescope, binoculars or camera that has a special solar filter on the front, which acts the same way eclipse glasses would.

Sunglasses won’t work in place of eclipse glasses or solar viewers, which are 100,000 times darker and held to an international safety standard. While sunglasses can protect our eyes from harmful UV rays during everyday activities, they are not intended for use when looking directly at the sun.

The lenses of solar eclipse glasses are made of black polymer, or resin infused with carbon particles, that blocks nearly all visible, infrared and ultraviolet light, according to The Planetary Society. Sunglasses don’t block infrared radiation.

To find safe manufacturers and resellers of eclipse glasses and filters for optical devices, including cameras and smartphones, check out the list curated by the American Astronomical Society.

Put on your eclipse glasses before looking up and remember to turn away from the sun before you remove them again. Always keep an eye on any children wearing eclipse glasses to make sure they don’t remove them while looking at the sun.

If you normally wear eyeglasses, keep them on and put eclipse glasses over them or hold a handheld viewer in front of them, the American Astronomical Society advises.

Don’t look at the sun through any unfiltered optical device — camera lens, telescope, binoculars — while wearing eclipse glasses or using a handheld solar viewer, according to NASA. Solar rays can burn through the filter on the glasses or viewer and can cause severe eye damage, given how concentrated the rays can be through an optical device.

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