So. You want to watch the eclipse on Monday and you think that you don’t need any of those "safety" eclipse glasses. That's a fantastic way to cause permanent damage to your eyes.
Unless the Sun is completely covered by the Moon, you really shouldn't look at it directly. Even a tiny sliver of our star is bright enough to hurt you. Sunlight triggers chemical reactions in the back of your eyes, which is what allows you to see. But if you are exposed to too much light, those chemical reactions are pushed to the limit and the retina gets a chemical burn. This is called solar retinopathy.
Knowing that you’re literally burning your retinas might already be enough to discourage you looking directly at the Sun, but let’s make it perfectly clear what the consequences are: Your eyes may become extremely sore, you might be unable to see shapes and details of objects, and these may appear a funny color. Your vision may be distorted and you could develop blind spots.
If you have mild damage, these impairments to your vision might last for a month or up to slightly over a year. If the damage is more severe, those symptoms become permanent. So please be safe and follow the guidelines to enjoy the eclipse safely. Buy good solar glasses because they can filter all but 0.003 percent of visible light as well as ultraviolet and infrared light.
Another important warning is to use filters for cameras, binoculars, or telescopes to see the eclipse. These instruments can significantly magnify the light we get from the Sun and you need to stop a lot more solar radiation to be safe. And no, solar glasses cannot be used with those. They are not good enough to protect against magnified light, so use the appropriate equipment.
Last year, a British astronomer made a crude but effective demonstration of the danger of looking at the Sun through a telescope. He pointed a telescope with a 50x magnification towards the Sun and put a pig’s eye in front of the ocular. Twenty seconds later the eye started smoking. Don’t be that pig’s eye.
A solar eclipse is an incredible event and it's great that so many people want to experience it, but please don't harm yourself while doing so.
If you haven't managed to grab yourself a pair of safety glasses, don't worry. Here's our guide to viewing the eclipse without injuring yourself, using just regular household items.