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Total solar eclipse 'once-in-a-lifetime' opportunity, says prof

Collingwood optometrist offers advice for protecting your eyes during the eclipse
03242024solareclipsepathmap
A map showing where to see solar eclipses until 2040. The total eclipses are in blue.

Even though the Collingwood and Barrie area won’t be entirely in the “path of totality” for next week's total eclipse, it will still be a “pretty cool” sight, according to one expert.

Wolfe Wall, an astronomy professor at Lakehead University for more than two decades, said Barrie, like Thunder Bay, where he teaches, won’t experience a total solar eclipse.

“It’s just going to be a partial eclipse. The moon is coming between the sun and the Earth and casting a shadow on the Earth. There are two parts of a shadow. One part is where all the light is blocked off. The other part is where the moon is just covering a little bit of the sun,” he explained.

In order to experience a total eclipse on April 8, Wall suggests travelling to Hamilton.

“If you do that, then you will get a minute-and-a-half of total eclipse. Considering what the future has in store, this will be a once-in-a-lifetime thing,” he said. “It’s also the most spectacular part. It’s the part where you can see clearly the corona, which is a glow around the sun. That is interesting. When the moon first fully covers the sun, you get something called a Baily’s bead — diamond ring or, more rarely, double diamond ring effects — which is a spectacular thing to see as well.”

Most of the province will not be in the path of totality, he noted. However, the cities of Hamilton, Niagara Falls, Kingston and Cornwall will see a total eclipse.

“You will have to travel thousands and thousands of miles and wait years to get an opportunity again ... It’s nice and fun to watch it with your own eyes, as it were, to see the little piece of the sun that gets taken out by the moon. That’s kind of a cool thing to see,” Wall said.

“If you look at the map, the sharp shadow cast by the moon is on a very small part of the Earth. This is super special because that part of the Earth is close to there. That won’t happen for another 50 years, at least.”

When the Earth goes around the sun, it does so in a flat plane, he explained, adding the moon rotates around the Earth in a similar plane, but it’s at a bit of an angle to the ecliptic, meaning it only crosses the ecliptic at two places.

Those are called nodes, he added.

“To get a solar eclipse, you have to have the sun being very close to one of those two nodes, and that happens, like, twice a year, and that has to be close to the moon at the time the moon is new. Every eclipse season, which happens twice a year, somewhere on Earth gets to see at least a partial eclipse,” he said.

It’s only during a total solar eclipse, Wall noted, that people can safely view it without special glasses, during that minute-and-a-half.

The best items for that, he said, are special eclipse glasses, which Wall said he purchased for $3 on Amazon.

“It’s not expensive. There’s an ISO rating that says you’re not going to go blind if you use them to stare at the sun. When I put them on, I can’t see anything unless I am looking directly at the sun. That’s how strong these are,” he said.

Collingwood optometrist, Andrew Comly said his office has been busy selling eclipse glasses this week, which are now sold out. 

While the solar eclipse is exciting, Comly said there are dangers to avoid. 

"When you're staring at the sun ... you can get something called solar retinopathy, which is essentially burns to your retina," said Comly. 

During the eclipse, the risk is higher for two reasons. 

"Because the sun is being blocked out, your pupils will dilate more and allow more light in, and you also don't have the same sensitivity as you normally would if you were, say, staring at the regular sun, which you also shouldn't do," said Comly. "It's more dangerous when you're looking at a solar eclipse because your reflexes aren't necessarily there to protect you." 

It's for these reasons he urges special caution for kids and pets who may not understand the dangers. 

"Keep your pets indoors ... be careful with children, you can't necessarily trust them even if they have the solar eclipse glasses, you just have to keep a very, very careful watch on them," said Comly. 

There is no procedure to repair solar retinopathy, so any damage is potentially permanent. 

"If it's mild, sometimes you can recover from it, but if it's a major burn, then it's irreversible because it's neural tissue, it won't grow back," said Comly. 

He said it's important to use solar eclipse glasses to protect your eyes if you're going to watch the eclipse outside, and warns that regular sunglasses are not nearly strong enough to protect your eyes in this situation. 

If you don't have access to eclipse glasses that meet the ISO 12312-2 international safety standard, Comly suggests watching a live stream of the eclipse from indoors. 

Wall has created a pinhole camera using a milk carton, which is another option, though would offer a pretty “small” view.

“It is disappointingly small, but the truth is the sun is disappointingly small. Although it’s important to us, the diameter takes up about a half a degree of angle … as is the moon … and that’s sort of why we get these spectacular solar eclipses, because the moon and the sun are almost at the same angle, so the moon nearly perfectly covers up the sun,” he said.

The light from the sun during an eclipse, Wall noted, isn’t any more dangerous to the eyes than it would be at any other time or day, but given the rarity of an eclipse, he acknowledged people would likely be more apt to “look up” and stare.

“If you stare at the sun right now, and do it for long enough, you will end up with permanent eye damage. Quite possibly, 20 seconds might be long enough. I know from my own experimental experience, I don’t want to look at the sun much more than half a second. The trouble is you might be tempted to stare at it for a long time,” he said.

The last partial eclipse, recalled Wall, occurred on Christmas Day in 2001, so the fact there are places in Ontario where a total eclipse will occur is “really special,” he said, adding he’s keeping his fingers crossed for a clear sky on April 8.

“Maybe it’s totally obvious, but I should mention, in the event of cloud cover, it’s really a non-event,” he said.

With files from Erika Engel