With solar eclipse glasses selling out across the country, Brits have been advised to get creative in how they watch the display safely. Looking at an eclipse with the naked eye can cause damage, as bright rays from the Sun can burn the cells in the retina at the back of the eye. As the retina doesn't have pain receptors, the damage isn't felt as it happens, but it can result in vision loss or blurry spots that may become permanent.
Check Your Glasses for Safety Certification
If you're lucky enough to get your hands on the special eclipse glasses, make sure they have the safety certification "ISO 12312-2" or "ISO 12312-2:2015" printed somewhere on them. This means they are legitimate and will only allow a small amount of light to pass through. Regular sunglasses are not good enough, as they don't block enough light and therefore can still cause permanent eye damage.
Make a Pinhole Projector
Otherwise, pinhole projectors can be made by making a hole in a piece of card with a pen, then holding the card in one hand and a blank piece of paper in the other. Facing away from the Sun, line up the card and paper so an image of it becomes visible.
A pinhole viewer can also be made with an empty cereal box, which blocks out the surrounding sunlight and allows light in only from the direction of the eclipse. Cut out a piece of paper and stick it to the bottom of the box, then tape the box shut. At the top, cut out a small square so you can see the paper at the bottom, then cut out a matching small square at the top.
Cover this square with foil and tape it down before poking a hole in it using a pin. Stand with your back to the Sun and use one eye to look through the open square.
Use a Colander
Another affordable and accessible way to safely enjoy the eclipse is with colanders, which work similarly: by holding them up and looking at the shadow they cast, multiple projected images of the eclipse become visible.
Imo Bell, a planetarium astronomer at the Royal Greenwich Observatory, told the Press Association: "It’s not a total eclipse, but over 90% is really exciting. We’re not going to get one this good for a really long time. So it’s important not to miss it, and to be prepared. You can’t just go out and expect to have a look because it’s really dangerous for your eyes."
"So you can use solar eclipse glasses, which are very, very different from sunglasses – they block out so much light that you can’t see anything through them except the Sun, because that’s how much light they need to block for the damaging light of the Sun to be safe to view."
"Ideally a solar telescope is an amazing way to witness it, and if you don’t have one of them then you can look into whether your local astronomy society is doing any events."
"And if all else fails, you can project the image of the eclipse using a household item like a colander which has lots of holes in – point the colander towards the Sun with your back facing it, and in the shadow of the colander you’ll be able to see the eclipse in the holes, which is really cool."
