Solar eclipses happen every year. There are at least two, and sometimes as many as five, that carve their way somewhere around the Earth.
But whether or not you get to see them depends on where you live. The sun might slide behind the moon somewhere over the Pacific Ocean, for example, leaving few opportunities for viewers to take in the spectacle. Or it might occur on the other side of the earth while your home is shrouded in night, leaving no better option than staring up at the night sky.
Then there are the different degrees of eclipse. A partial solar eclipse, when the moon blocks part of the sun but not all of it, is more common than a total solar eclipse, when the entirety of the sun is obscured and day briefly turns to night.
So despite the relative frequency of eclipses, what is happening today is rare. In the United States the last total eclipse was 38 years ago, in March of 1979. And if you miss today’s event, the next opportunity to see one isn’t until 2024.
So get excited, and make sure you go see it. But whatever do, don’t look at it!
That’s right, don’t look at it. These beautiful, stunning rare events are extremely dangerous, at least for your eyes. It is never safe to look directly at the sun, and an eclipse is no different. Even wearing sunglasses is not enough to keep your eyes safe for watching. If you are going to take in this celestial spectacle, you need to be prepared.
There are a handful of easy safe ways recommended by NASA to view the sun today. The easiest is through a pair of special eclipse viewing glasses. They look like the old 3D glasses, but instead of one red lens and one blue they have special dark lenses rated to the ISO 12312-2 international safety standard. Anything less is not enough.
Another option is a welding mask, but be sure the filter’s shade number is adequate. NASA suggests a rating of 14. Few welding masks are rated this dark. If yours is not, don’t use it.
Another option that might require a bit of creativity but is a fun way to look at the sun is the projection method, where a pinhole allows the projection of the sun onto a surface. Instead of looking directly at the sun you watch the projection, which is safe on the eyes. There are a number of options for how to project the sun, from two sheets of paper held parallel to building a camera obscura from a cardboard box to transforming a pair of binoculars into a focusable projector. These keep your eyes looking away from the sun and its direct rays, which in turn keeps them safe.
According to the Solar Center at Stanford University, those in the exact path of the total eclipse can look up when the sun is fully covered by the moon, at the point when the sky goes dark, but for most of us viewing the eclipse requires protection. And even in the direct path there is ample opportunity to damage your eyes. Be safe, and if in doubt look away. The next U.S. eclipse is seven years from now — chances are you’ll want to use your eyes a lot between now and then.