Here’s what you need to know about Monday’s total solar eclipse

August 22, 2017 GMT

Whether you’re one of the millions of Americans planning to watch Monday’s total solar eclipse as it moves across the country or you’re hearing about it for the first time, here’s what you need to know:

What is a solar eclipse?

A solar eclipse, according to NASA, is when the moon passes between the sun and earth, blocking all or part of the sun’s light. During the eclipse — the first one in the contiguous United States since 1979 — the afternoon sky will look more like twilight and the sun’s outer-atmosphere, the corona, will be visible.

Depending on how much of the sun is covered by the moon, bright stars and the planets can become visible and animals change their behavior, according to NASA: Birds nest, cows head back to the barn and crickets chirp.

Where can I see the solar eclipse?

Viewers in Madison will witness a partial eclipse. About 85 percent of the sun will be covered, with the peak at about 1:15 p.m, causing the sun to look like a thin crescent moon. From beginning to end, the event should last about three hours.

In portions of places like Oregon, Illinois and South Carolina, where the eclipse’s path of totality will pass through, the moon will briefly block the whole sun. The peak duration will be in Carbondale, Illinois, where the sun will be completely covered for about 2 minutes and 40 seconds.

If you can’t make it outside, NASA will live-stream the event starting at 10:45 a.m. To watch NASA’s broadcast, go to go.madison.com/watch

Of course, none of those details matter if your view is blocked by clouds. In Madison, Monday’s forecast calls for a 50 percent chance of showers and thunderstorms with mostly cloudy skies, according to the National Weather Service.

Can it hurt my eyes?

Yes, looking directly at the solar eclipse can result in impaired vision or blindness, according to the American Academy of Ophthalmology. The sun’s bright light overstimulates the retina and causes a condition called solar retinopathy.

To avoid eye damage, specialized glasses — not sunglasses — or other filtering devices must be used.

But those glasses have become nearly impossible to find and counterfeits have flooded the market.

For more information on legitimate manufacturers of the glasses and how to spot a fake, go to eclipse.aas.org/resources/solar-filters

What if I don’t have a pair of “eclipse glasses?”

Suppliers were rushing glasses to retailers late last week; it’s possible shipments will still arrive before the actual event.

If you’re with a lot of people, chances are someone will have a pair and will be happy to share.

But if all else fails, you can still watch the eclipse by creating your own pinhole projector. Pinhole projectors, which can be made from a cereal box and some paper, show the shadow of the moon blocking out the sun by filtering the light through a small hole.

To make your own, put a piece of paper on the bottom of a cereal box and cut two holes on the left and right side of the top of the box. Cover one with aluminum foil and poke a hole in it with a pin. With your back turned to the sun, let the light filter through the small hole and then look at the projection through the uncovered hole.

To learn more about pinhole projects, go to eclipse.aas.org/eye-safety/projection or watch a video at go.madison.com/pinhole

When will the next total solar eclipse be visible in the U.S.?

If you miss Monday’s eclipse, you have about seven years to plan for the next one. On April 8, 2024, another total eclipse will occur in the U.S., with the path of totality passing over states like Texas, Illinois, Ohio and New York.