Partial solar eclipse to be visible across Canada on Saturday

On Saturday, the moon is going to take a bite out of the sun. Just how much, depends on where you are in the country.

The celestial event is part of an annular eclipse, an event where the moon doesn't entirely cover the face of the sun, but instead leaves something viewers like to call a "ring of fire."

Though Canada isn't in a position to view the annular eclipse, it will experience a partial eclipse.

Total solar eclipses occur when the moon covers the entirety of the sun. That's thanks to the fact that the sun's diameter is 400 times bigger than the moon's.

However, the sun also happens to be 400 times farther away. But we don't get a total eclipse every month because the orbits of both the sun and the moon aren't perfect circles, but rather elliptical.

Annular eclipses occur when the moon happens to be closer to Earth in its orbit and doesn't cover the sun entirely.

We get partial eclipses — where only a fraction of the sun is covered by the moon — when an observer is out of the path of totality or annularity, or when the moon just passes above or below Earth.

"While solar eclipses of any pedigree occur on average twice a year somewhere on Earth, annular eclipses are rarer," said Paul Delaney, professor emeritus at York University's department of physics and astronomy in Toronto.

"The moon needs to be further from the Earth than usual and be in the correct alignment with the sun for the annular eclipse to arise. This combination occurs on average once every two to three years."

How to watch it — safely

How much of the partial eclipse you can see depends on where you are. But the farther west you are, the better. For example, southern B.C. will experience the greatest eclipse, with roughly 75 per cent of the sun blotted out in Victoria and Vancouver.

The University of British Columbia is having a viewing party from 8 a.m. to 10:40 a.m.local time on Saturday.

There's an app for iPhones called Totality from Big Kid Science that offers a drop-down list to show you the path of the eclipse. It also allows users to tap on their location to see what the eclipse will look like from there. (It will also come in handy for next year's total solar eclipse on April 8, which will be visible across parts of eastern Canada.)

Even though most of the sun will be covered this weekend, don't expect to notice any real dimming of daylight. That also means, don't look directly at the sun without proper protection.

"You must always observe the sun with caution and be sure the method you use is safe," Delaney said. "Projected image is arguably the best way — projecting an image of the sun from a telescope onto a piece of paper or such."

He said the Royal Astronomical Society of Canada offers eclipse glasses that are safe for viewing the sun, or you could use Number 14 welder's glasses.

There are also online viewing opportunities should you not have any eye protection or if you're clouded out.

NASA will be broadcasting the eclipse from 11:30 a.m. to 1:15 p.m. ET on its YouTube channel. The Virtual Telescope Project will also be hosting live coverage of it beginning at 12:30 p.m. ET from three different locations: Panama, Arizona and Florida.

"However you choose to observe the event, it is worth spending the time around maximum obscuration to witness one of nature's very special displays," Delaney said.

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