Just a warning to anyone interested in the coming eclipse. Avoid the glasses sold at Canadian Tire. I just bought two pairs of eclipse glasses at Canadian Tire. I decided to test them right after I got outside and immediately noticed an issue. Both glasses have a hazy appearance around the sun.
With proper eclipse glasses the sun should appear crisp and not too bright. You should be able to distinctly see the edge of the sun and even see detail on the surface. There should be no haze of any kind. If you see any kind of haze, immediately take off the glasses and throw them out.
I knew the glasses from Canadian Tire were suspect because they had "NASA APPROVED" on the sides, which is why I bought them. I wanted to test them.
There is no such thing as "NASA APPROVED". NASA doesn't approve or certify anything. If you see that, it's a massive red flag.
One very good trusted source for where to buy eclipse glasses is the American Astronomical Society which has a list of trusted vendors. I myself bought a bulk quantity from solareyewear.ca and have tested the glasses to be working properly.
https://eclipse.aas.org/eye-safety/viewers-filters
Unfortunately, there will be a massive amount of scams going around with eclipse glasses and shady people trying to make a quick buck. Don't risk it and make sure your glasses will protect your eyes.
If someone tries to convince you that their glasses are genuine because they have ISO-12312-2 printed on them, it doesn't matter. I could print that on a pair of toilet paper rolls taped together, but that doesn't mean it'll protect your eyes.
Here are some resources to check out:
https://aas.org/press/american-astronomical-society-warns-counterfeit-fake-eclipse-glasses
During an annular eclipse this is true. But during the totality phase of a total solar eclipse, the entire sun is being blocked (UV doesn't magically travel through the moon).
An annular eclipse is when the moon is the furthest away from Earth. A total eclipse is when the moon is close enough that the angular size of the moon is larger than the sun. So all light is blocked for a couple minutes. The few moments right before and right after totality are the most dangerous because most of the sun is covered and it doesn't hurt the eyes, but can still be damaging.