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Eclipse Q&A with Bill Nye - What is a solar eclipse?

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Solar eclipses are one of the best cosmic spectacles that you can see from Earth. Learn how total solar eclipses happen and why they're rare. More eclipse info:


"Hey Bill, what is a solar eclipse?"

I'm glad you asked. Let's take a look. An eclipse occurs when the Sun and a moon and a planet line up. You may not have thought about this, but the Sun is always casting light out in every direction, all throughout the Solar System. And when that light strikes something like a moon, then the moon blocks some of the light and it casts a shadow like the shadow here on the table.

If a planet, let's say the Earth, for example, happens to be lined up just right with the Moon and the Sun, then a shadow will streak across the Earth's surface. That right there, that's a solar eclipse happening. And if you're in the very middle of the shadow, then you experience what we call totality. That means the entire Sun is completely, totally covered.

It's going to be a totally awesome total eclipse. We'll see you out there.