It’s perfectly safe to look at the total phase of the eclipse with the eye alone. In fact, experts say it’s the best way to enjoy the spectacle. But the entire eclipse actually lasts more than two hours, from the moment the Moon first appears to touch the solar disk to the moment of last contact, and, of course, most of the country won’t see totality. During those partial phases of the eclipse, your eyes need protection from the Sun’s blinding light; even a tiny sliver of direct sunlight can be dangerous. Here are a few tips for watching the partial eclipse safely.

• Use commercially available eclipse viewers. These can look like eyeglasses, or they can be embedded in a flat sheet that you hold in front of your face. Their dark coating allows you to watch the Moon as it encroaches on the solar disk throughout the eclipse. Inspect your viewer before you use it, however, to make sure there are no scratches to let in unfiltered sunlight. And keep them on until the Sun is fully eclipsed!

[Mark Margolis/Rainbow Symphony]

• Use a piece of welder’s glass (No. 14 or darker).
• Use a pinhole camera. You can make one by poking a small hole in an index card, file folder, or piece of stiff cardboard. Let the Sun shine through the hole onto the ground or a piece of paper (don’t look at the Sun through the hole!). The hole projects an image of the eclipsed Sun.
• Stand under a leafy tree and look at the ground. The gaps between leaves act as lenses, projecting a view of the eclipse on the ground. With an especially leafy tree you can see hundreds of images of the eclipse at once.