During a solar eclipse, the shadow of the moon moves across the surface of Earth as the moon travels between our planet and the sun. Thanks to a cosmic coincidence – the fact that the sun is both about 400 times larger than the moon and about 400 times as distant – when the two line up just right, they appear the same size and the moon completely covers the disc of the sun in a total eclipse.Â
Totality, the period in which the disc of the sun is completely hidden, is the only time when it is safe to look directly at the sun; otherwise, looking at the sun can burn your retinas and cause vision loss. But during a partial eclipse, or even when no eclipse is happening at all, you can still look at the sun – you just need proper eye protection or a clever trick to project its image so you don’t have to look directly at it. Here are four ways to look at the sun without burning your eyeballs.
- Wear eclipse glasses
This is the safest way to view a solar eclipse, and the only one that actually involves staring straight at the sun. Regular sunglasses won’t do the trick: eclipse glasses are about 100,000 times darker, letting through only a tiny fraction of sunlight to protect your eyes.
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Looking through a pair of eclipse glasses, or any other kind of proper solar filter, you shouldn’t be able to see anything but the sun – even the brightest indoor light should appear extremely dim. The American Astronomical Society has put together a list of trusted suppliers, which you can see .
If you aren’t sure about the safety of your eclipse glasses or if they don’t seem quite dark enough, stick with one of the other methods on this list. If you are looking through a telescope or binoculars, eclipse glasses won’t be enough to protect your eyes – make sure any magnifying device has a proper solar filter over its objective lens or lenses, which are the ones through which light enters the device.
- Use the shadows
The easiest way to view a partial eclipse doesn’t require any special equipment at all. When light passes through a small opening, it projects the shape of whatever emitted it onto the next surface that it hits.
During a partial eclipse, this means you can use shadows to see how much of the sun is hidden behind the moon. Anything can create the small openings necessary for this: a colander, cheese grater, straw hat or even your outstretched hands with fingers creating a sort of grid shape.
Even just standing under a tree and looking at the shadows cast by the leaves can reveal a smattering of crescent sun shapes on the ground.
- Pinhole projection
If you want to get a little bit more involved, you can use the same effect to create a pinhole projector, which is essentially just a surface with a tiny hole poked in it.
If you take a cardboard box and poke a small hole in one end with a pushpin or pen, the shape of the sun will be projected on the other end. All you have to do is face away from the sun with the hole pointing towards the sun and look down to the other end of the box (if you have a big enough box, you can even put your head inside – if not, you might have to cut a slot to look through in the same side as the hole) and the shape of the sun will be projected there.
Don’t look through the tiny hole, because your head will block the light that should be shining through it. Looking through the hole directly at the sun will still burn your eyes, so you should only look at the projection on the other end of the box.
- Mirror projection
This projection method is similar to the others – the theme being, don’t look right at the sun – but may be easier if you want a large projection of the sun that lots of people can look at.
All you need is a small, flat mirror and some way of angling it so that it reflects the sunlight onto a flat surface such as a wall or screen. If you cover the mirror almost entirely using a sheet of paper or cloth with a small hole cut in the middle, it will work just like the pinhole projector to shine an image of the sun on the wall.
The smaller the hole is, the sharper the image will be, although it will get dimmer as less light shines through. But if you can get your image big or sharp enough, you might even be able to see any sunspots that happen to be pocking the sun’s face during the eclipse.
Once again, don’t look at the sun via its reflection in the mirror, which is just as dangerous as looking directly at it if you don’t have eclipse glasses on. Only look at the projection of the sun, and you will be able to enjoy the eclipse without any unnecessary visits to an ophthalmologist.
Total solar eclipse tours and cruises
Explore our tours and cruises designed to help you make the most of experiencing awe-inspiring solar eclipses in handpicked locations around the world.
