Updated 8/21/2017 9:06 a.m.

NEW YORK (CBSNewYork) — As we all know, the Earth revolves around the Sun, and the Moon revolves around the Earth.

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But at least twice a year, they fall into alignment, creating an eclipse – be it a lunar eclipse, a solar eclipse, or a total solar eclipse.

That’s the big show, where the Moon completely blocks out the Sun.

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It’s only possible because – even though the Sun is 400 times larger than the Moon, the Moon is 400 times closer to the Earth.

When the Sun hits the Moon and casts its shadow on the Earth, you get a couple different types of shadows.

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Most people will see a penumbra, or partial shadow, where you still see a portion of the Sun. But a select few, will see an umbra, where the Moon completely blocks out the Sun.

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It’s called totality and the area where it hits on the Earth is known as the path of totality.

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On Monday, it goes from Oregon to South Carolina.

So in Charleston, South Carolina people are going to a get a bonafide 100 percent solar eclipse. Places like Portland, Oregon are going to get about 99.5 percent.

If you move to the north or south of the path of totality, that percentage will drop. 

In the Tri-State area, we’re expected to see about 71 percent of the Sun obscured by the Moon.

“We’re only going to see about a 70 percent eclipse, which means there will still be a third of the sun coming through, which can instantaneously cause one to be blind,” eye surgeon Dr. Stewart Levine told WCBS 880’s Sophia Hall.

He warned some of the solar viewing glasses may be fake.

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“If you have eclipse sunglasses, you can hold them over the lenses of your phone and take a picture that way. Without looking at the sun yourself, you’re indirectly looking at the eclipse,” he said. “But I think the best way and the safest way is to watch it on a live streaming website, where you’ll see it in totality, from a good location, and a totally safe environment.”