You've likely never seen a total solar eclipse. Here's where and how to watch April's upcoming show

On April 8, the moon's shadow will glide across Mexico, into the United States and finally into Canada, producing one of nature's greatest spectacles: A total solar eclipse.

But if you want to see it, you'll likely have to travel to eastern Canada — and into a very narrow path that stretches from southern Ontario, through Quebec into New Brunswick, P.E.I. and Newfoundland. (In Nova Scotia, only the Meat Cove area will experience totality.) 

Total solar eclipses occur when the moon passes in front of the sun, blocking out its light. The path of that shadow is extremely narrow, which is why most people have likely never seen one.

"People … think that solar eclipses are extremely, extremely rare," said Fred Espenak, a retired NASA astronomer and the agency's lead eclipse expert. "The rare part of total solar eclipses is that they're only visible from a very small fraction of the Earth's surface, typically less than about one-half per cent of the Earth's surface for a given total solar eclipse."

Given that, the average for any one spot on Earth to see a total eclipse is about once every 375 years, he explained. And that's why most people haven't experienced a total solar eclipse.

However, many people have likely experienced a partial solar eclipse, where it looks like something has taken a bite out of the sun. That's because the visibility of those is far wider. For next month's eclipse, outside of that narrow path of totality, the rest of the country will experience a partial eclipse in some form. 

But seasoned eclipse chasers say there's a very big difference between a partial and a total solar eclipse.

Espenak, who has seen 24 total solar eclipses, said a partial eclipse is lovely, but there's nothing like a total.

"People have to understand that even if someone may have seen a partial eclipse, they think that's the whole thing. It's just a degree of a percentage," he said. "They saw a 50 per cent partial or an 80 per cent partial — that 80 per cent is as good as a total. Well, it's not. 

"Seeing a partial eclipse is like getting five out of the six numbers in the Powerball. To win the jackpot, you've got to get all six numbers. And to win the jackpot with eclipses, you've got to be 100 per cent."

Jay Anderson, a former meteorologist with Environment and Climate Change Canada and an avid eclipse chaser, said the experience of standing in the moon's shadow is unforgettable. 

"The eclipse itself is the marvel: the prominences, chromosphere, the corona, all of which are parts of the solar atmosphere that suddenly pop into view that average person wouldn't see.

"And the temperature drops and the shadow comes in," he said, "and you're looking up at the sun and you're watching that last little bead [of light] squeeze off, and you get the diamond ring, and — whomp — you're into that darkness. But you're seeing the corona appearing before the sun is completely covered.

"Then when it's over, there's a lot of hugging and shouting, and a few tears and marriage proposals sometimes."