How to Watch an Eclipse Without Damaging Your Eyes

There is exactly one moment during an eclipse when it is safe to look at the sun with your naked eyes, and it lasts a couple of minutes at most. Every other second (before it, after it, and during every partial eclipse there has ever been) you need a proper filter or you are burning your retina.

That sounds dramatic. It isn't. The damage is called solar retinopathy, and the cruel part is that it doesn't hurt. Your retina has no pain receptors. You look, it feels fine, you look again, and the symptoms turn up hours later as a blurred or blank patch in the centre of your vision. Sometimes it fades over months. Sometimes it doesn't.

The good news is that this is an entirely solved problem. A pair of certified eclipse glasses costs a few pounds, a piece of card costs nothing, and either one makes an eclipse one of the best things you will ever stand outside and watch.

Know which kind of eclipse you're getting

The safety rules are completely different depending on the type, and people get hurt by applying the rules from one to another.

A total solar eclipse is the only one with a safe naked-eye moment. When the moon covers the sun's disc completely (totality), the blinding photosphere is gone and you can, and absolutely should, look directly at it. That window is typically two to four minutes, occasionally up to seven. The instant the first sliver of sun reappears, the filters go back on.

A partial solar eclipse never has a safe moment. The moon takes a bite out of the sun and the remaining crescent is exactly as damaging as the full disc. It is dimmer, which is worse, not better: dimness is what tempts people to stare.

An annular eclipse, the "ring of fire", is the one that catches people out. The moon is too far from Earth to cover the sun completely, so a bright ring remains at maximum. It looks like totality in photographs. It is not. There is no safe naked-eye moment in an annular eclipse, at any point, ever.

A lunar eclipse is completely safe. You're looking at the moon sliding into the Earth's shadow, turning a deep copper red. No filters, no equipment, no risk. You can watch it for hours with a cup of tea.

What protects your eyes

The standard to look for is ISO 12312-2. That's the international specification for filters designed to be looked through directly at the sun, and it should be printed on the glasses or handheld viewer themselves. Buy from a reputable astronomy retailer or a national astronomical society rather than a marketplace listing, because counterfeits with the marking printed on them are a known problem.

Certified eclipse glasses are so dark that in normal use you should see nothing through them: not lights, not furniture, not the sky. If you can make out anything at all indoors apart from a bare bulb filament, don't use them. Check them before the day: hold them up to the light and look for scratches, pinholes or separation around the frame, and bin them if you find any.

What does not work, no matter what anyone tells you:

• Sunglasses. Any sunglasses. Polarised, "UV400", several pairs stacked. They are thousands of times too bright.
• Smoked glass, exposed photographic film, CDs, mylar crisp packets, space blankets. All old folklore, all inadequate.
• Looking through cloud, mist or haze. It cuts visible brightness while doing far less about the infrared and ultraviolet doing the damage.
• Looking briefly. There is no safe short glance. The injury is cumulative and painless.

Welder's glass of shade 14 or darker is the one traditional alternative that works, but shade 12 and below, which is what most people have in the shed, does not. Unless you know the shade number for certain, use eclipse glasses.

The mistake that blinds people

This is the part worth reading twice, because it is not obvious and it is the one that causes the most serious injuries.

Never look through binoculars, a telescope, or a camera viewfinder while wearing eclipse glasses.

The glasses are designed to sit between your eye and an unmagnified sun. Any optic in front of them gathers light across its whole aperture and concentrates it into a beam that will melt through the filter in a fraction of a second and then continue into your eye. People have been permanently blinded doing exactly this, believing they were being careful.

If you want magnification, the filter goes on the front of the instrument, over the objective lens or the open end of the tube, never at the eyepiece. It must be a purpose-made solar filter, sized to fit and fastened so a gust of wind cannot lift it off. Anything that slots into the eyepiece, including filters sold with cheap telescopes decades ago, is dangerous, because it sits at the focus of all that concentrated heat and can crack while you are looking through it.

Same principle for a phone. Pointing a phone at the sun risks the sensor, but the real danger is you squinting up to line up the shot. If you want a picture, tape a spare pair of eclipse glasses over the lens and frame it on the screen at arm's length.

The free method that's better than it sounds

You do not need to buy anything. Pinhole projection works well and is safe, because you never look at the sun at all: you look at a picture of it on the ground.

Take a piece of card and make one small, clean hole in it with a pin. Stand with your back to the sun, hold the card up, and let the sunlight fall through the hole onto a second piece of card, a wall, or the pavement below. You will see a small disc of light. That's an image of the sun, and during an eclipse you'll watch a bite disappear out of it. The further apart the two cards, the bigger and dimmer the image.

The rule is simple: the sun is always behind you and you are always looking away from it. Never look through the hole.

Once you know what you're looking for, you'll see it everywhere. A kitchen colander throws dozens of crescents at once. So does a cheese grater, or a straw hat. Best of all, so does any leafy tree: the gaps between overlapping leaves are thousands of natural pinholes, and during a deep partial the ground under a tree becomes carpeted in hundreds of overlapping crescent suns. It is the strangest and most beautiful part of the whole event, and most people miss it because they are looking up.

What to watch for

Eclipses reward people who know the sequence, because a lot of it is easy to miss.

In the hour before maximum, the light goes wrong before it goes dark. Colours flatten, shadows sharpen to an odd crispness, and the temperature drops noticeably. Several degrees is common. Birds go quiet and start roosting. If there's livestock nearby, watch them rather than the sky for a minute.

In the last moments before totality, look at the ground for shadow bands: faint rippling lines of light and dark, like the pattern on the bottom of a swimming pool, sliding across pale surfaces. They're elusive and a white sheet laid on the ground gives you the best chance.

Then, if you're in the path of totality: Baily's beads, the last points of sunlight shining through valleys on the moon's edge, collapsing to a single brilliant point, the diamond ring, and then out. That is your cue. Glasses off. The corona appears, a pearl-white halo streaming out around a black disc, and it looks nothing like any photograph of it. The horizon glows sunset-orange in every direction at once, because you are standing inside the moon's shadow and looking out at daylight in all directions.

Watch it. Don't fiddle with a camera. You have two minutes and there are better photographs of eclipses on the internet than you are going to take.

Then the first bead of light returns on the other side, and the glasses go straight back on.

Today, as it happens

There is a total solar eclipse today, 12 August 2026, with the path of totality crossing Greenland, Iceland and northern Spain.

From the UK it is a partial: a substantial one, more so the further west you are, but partial. Which means everything above applies for the entire duration: there is no safe naked-eye moment at any point, not even at maximum. Filters or pinhole projection, start to finish.

Check timeanddate.com or the Royal Astronomical Society for the times and the coverage where you live, because both vary a lot across the country. It falls in the evening with the sun low, so a clear western horizon matters more than usual. If you're anywhere with a view west, that low sun and a hedge full of pinhole crescents makes for a good hour.

If you have no filters and it's too late to buy any: the card-and-pinhole method takes two minutes and costs nothing. Don't improvise a filter instead.

If you're wondering when totality next crosses the UK mainland: the last was Cornwall in August 1999, and the next is not until 2090. Travelling to one is, by broad agreement among people who have done it, worth the trip.

The short version

• Certified ISO 12312-2 glasses, or pinhole projection. Nothing else.
• Sunglasses never work. Nor does anything in the folklore.
• Never put eclipse glasses behind binoculars, a telescope or a viewfinder. Filters go on the front, or not at all.
• Naked-eye viewing is safe only during totality, and only in a total eclipse. Never in a partial. Never in an annular.
• Lunar eclipses are safe with no equipment at all.
• Check your glasses for pinholes and scratches before the day, and supervise children throughout.
• Look at the ground as well as the sky. The crescents under a tree are half the show.