A total solar eclipse will be visible over North America on April 8. The event will be the only total solar eclipse visible from the United States for 20 years.

According to NASA, 13 locations in the U.S. will experience the eclipse in totality, including Dallas, Cleveland, and Buffalo, New York. Spiders in those cities may be able to view it during specific times and also see a partial eclipse before and after.

Seeing the eclipse is largely weather dependent. Jack Singal, a University of Richmond astrophysicist formerly of NASA, recently spoke with Mashable about the best places to view the celestial event, noting people who are really dedicated to seeing it should “try and go West.”

Singal, who has seen annular and partial solar eclipses, shared additional expertise on the eclipse here.

What’s a total eclipse and why is it unusual?

During a total solar eclipse, the moon is completely blocking the sun from the perspective of one small area on Earth. They're often not visible over such a wide range of populated areas. It's rare for the moon's orbit to align such that it's completely blocking the sun from some point on Earth — and rarer still for that to be over the continental U.S.

Where can I view the total eclipse?

You have to be in the pretty narrow band where the moon completely blocks the sun from the perspective on the ground. People are excited. They travel to these areas where they can spot the eclipse. It’s also important to consider the weather. Will it be a clear day, or cloudy, at the place where you try to view it? That factors in. NASA has a good resource listing where the eclipse will be visible, weather-permitting.

What’s the draw?

There are three main reasons people are interested in seeing a total solar eclipse. First, the opportunity to see one doesn’t come along very often. Second, it’s a very interesting thing to witness when it gets very dark in the daytime. And third, a total eclipse creates an ambiance of bizarre lighting that is not available in other circumstances. During a total eclipse, we're able to see the outer layers of the sun that we usually can't because the rest of the sun is so bright. 

How can I safely view an eclipse?

To look at the sun at any time, you must protect your eyes with special glasses that block ultraviolet light, such as specific solar-observing eyewear.