It’s well known that you can’t look directly into the sun — especially if there’s a solar eclipse. But what happens if you look into a solar eclipse? And how do solar eclipse sunglasses work?

Here’s everything you need to know about solar eclipse sunglasses — and why you need them.

The sun is very powerful ... and our eyes are not

For a long time, we believed that if you looked at the sun, you would literally burn your retinas, similar to how a magnifying glass can burn a dry leaf, according to The Washington Post. But new research shows that does not happen; in fact, the retina’s temperature increases by only two degrees Celsius.

Yet it’s still enough to damage your eyes. The Cleveland Clinic explains that a specific medical condition occurs if you look at the sun (or any bright light) for too long, called solar retinopathy. Retinas help process sunlight to let us see, but are easily damaged and can cause a variety of symptoms such as headaches, watery eyes, blurred vision and, in severe cases, blindness.

Why do I need solar eclipse glasses?

If looking at the sun straight on isn’t dangerous enough, looking at it during a solar eclipse is worse. National Geographic explains that although the sun is being blocked by the moon, it’s not safer to look at.

Our pupils grow in size during the dimming of the sun, and once the sun starts to reappear, it will severely damage our eyes more, since our dilated pupils are allowing more light in.

You also shouldn’t look at the solar eclipse through your electronic devices, Healthline reports. Looking through your phone’s camera can damage your device and you can accidentally look at the sun while lining up your camera. Experts also urge people not to look at the solar eclipse through a telescope or binoculars, since these are known to cause worse damage to your eyes by magnifying the sun’s rays.

Scientists urge people to use approved solar eclipse glasses or alternative methods, such as the pinhole method, to view the solar eclipse, per National Geographic.

Solar eclipse glasses are specialized to be thousands of times darker than normal sunglasses, according to NASA, but if your pair is scratched or damaged, they suggest finding a new pair.

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How do solar eclipse glasses work?

The American Astronomical Society explains that official solar eclipse glasses reduce the sunlight levels so that your eyes don’t get damaged as you watch the solar eclipse. Official solar eclipse glasses undergo lab testing to determine how much UV, visible and IR light passes through them until they meet the international ISO standard.

There is a way you can test the solar eclipse glasses at home to make sure if they’ll actually protect your eyes, according to the American Astronomical Society. Real solar eclipse glasses, when worn, only allow you to see the sun and maybe the sun’s reflection or a super bright light bulb. You should not be able to see anything else.

If the sun is uncomfortable to look at while using your solar eclipse glasses, don’t use them and find a different pair.

What glasses are best for solar eclipse 2024?

Places you can buy ISO-approved solar eclipse glasses include science museums, planetariums, astronomy trade shows and some college astronomy departments, per the American Astronomical Society. They also provide a list of approved sellers that you can buy solar eclipse glasses from.

Avoid using solar eclipse glasses that appear damaged in any way.