Why the partial phases are the dangerous part

On 2 August 2027 the eclipse over Upper Egypt lasts roughly two hours and forty-five minutes from first contact to fourth contact. In Luxor that is 11:40 to 14:26 local time (EEST, UTC+3). Of that, about 6 minutes 20 seconds is totality. Every other second of the event — some 160 minutes of it — is a partial eclipse, and during a partial eclipse the Sun is exactly as dangerous as it is on any ordinary day.

It is more dangerous, in practice, because an eclipse makes people want to look. Normally nobody stares at the Sun; the glare and the blink reflex stop you within a fraction of a second. But when the Sun is 80% or 95% covered, the sky dims, the glare drops, the heat on your face eases, and staring upward suddenly feels comfortable. It is not. The remaining crescent is emitting the same intense visible, ultraviolet and infrared radiation per square millimetre as the uneclipsed Sun. Your pupil, responding to the dimmer overall scene, has opened wider and is letting more of it through.

The retina cannot feel pain

This is the single fact that makes solar viewing hazardous in a way people find counter-intuitive. The retina has no pain receptors whatsoever. You can burn it and feel absolutely nothing at the time. The injury — solar retinopathy, sometimes called eclipse blindness — is a photochemical and thermal burn to the light-sensitive cells at the macula, the tiny central patch of retina responsible for detailed vision. Symptoms typically appear hours later: a blurred or distorted patch in the centre of vision, a blind spot, altered colour perception, or a persistent after-image that never fades.

Some cases improve over weeks or months. Some do not. There is no treatment that reliably reverses it. People have lost the ability to read, to recognise faces, and to drive from a few tens of seconds of unprotected staring at a partly eclipsed Sun. The exposure needed is measured in seconds, not minutes, and children and young adults are more vulnerable because their lenses are clearer and pass more ultraviolet.

The one rule that covers almost everything

If any part of the Sun’s bright surface is visible — even a sliver, even 1% of it, even at 99.8% coverage in Aswan — you must be looking through a certified ISO 12312-2 solar filter, or not looking at all. The only exception in the entire two-and-three-quarter hours is the few minutes of totality itself, when the Moon covers the Sun completely and the corona is out. Everything else on this page is a footnote to that sentence.

Note what this means for the deep-partial towns. Aswan reaches 99.8% obscuration and Hurghada 98.5%, and at neither place is there any moment when it is safe to remove your glasses. A 99.8% eclipse is not “almost totality”; it is a partial eclipse with a very thin, very bright crescent. That remaining 0.2% is still thousands of times brighter than the corona.

ISO 12312-2: what to buy, and how to check it

Filters intended for direct viewing of the Sun are governed by the international standard ISO 12312-2, which sets limits on transmitted visible light, ultraviolet and infrared. A compliant filter transmits roughly one part in 100,000 of the visible light — about 0.001% — and blocks essentially all of the harmful UV and IR. Nothing you own that was not made for this purpose comes close.

What is not safe, no matter what anyone tells you

Sunglasses. Any number of pairs, stacked, polarised, mirrored, or “UV400”. They are designed to make a bright day comfortable, not to attenuate the Sun by five orders of magnitude.
Exposed or developed photographic film, including old black-and-white negatives and X-ray film. Modern colour film contains no silver in the developed image and blocks almost no infrared.
Smoked glass, candle-blackened glass, welding glass below shade 12. Home-made filters are unpredictable and can transmit dangerous infrared while looking reassuringly dark.
CDs, DVDs, foil, mylar food packaging, floppy-disc media, tinted car windows, water reflections, mobile-phone screens. None of these are filters.
Neutral-density photographic filters, variable NDs and polarisers. This one catches photographers out. A 10-stop ND reduces visible light by a factor of about 1,000 — impressive for long exposures, and roughly a hundred times too little for the Sun — and it does not block infrared at all. ND filters are for cameras on tripods, never for eyes, and see the optics section below for why they are also wrong for the camera.

Inspecting your glasses before you use them

Look for the wording “ISO 12312-2” printed on the glasses along with the manufacturer’s name and address. A bare CE mark on its own is not enough.
Hold them up to a bright household lamp. You should see the lamp filament faintly, or nothing at all. If you can make out the room, the furniture or your hand, they are not solar filters.
Check the film in strong indoor light for pinholes, scratches, creases or areas where the coating has lifted from the substrate. A single pinhole is enough to make a pair unusable. Discard rather than repair.
Check that the film is firmly attached to the card frame all the way round, and that the arms or frame have not been bent so that light leaks in at the sides.
Treat glasses that have been loose in a bag, in a hot car boot, or bought second-hand as suspect. They cost very little; your retina does not.

How to actually use them

Put the glasses on before you look up, look, then look away and remove them. Never walk around wearing them — a compliant filter is so dark you are effectively blind. And never look through a camera viewfinder, binoculars, a telescope or a telephoto lens while wearing eclipse glasses. The optics concentrate sunlight enough to melt the filter film in an instant, and the injury happens faster than you can react.

Bring your own, and bring spares

Do not plan on buying eclipse glasses in Egypt on the day. Bring them from home, in your hand luggage so they cannot be crushed, and bring two or three pairs per person. Glasses get sat on, dropped in sand, lent to a curious neighbour and not returned. Spares are the cheapest insurance in the whole trip.

Counterfeits: the real modern risk

The problem today is rarely someone deliberately using a CD. It is someone using a pair of glasses printed with “ISO 12312-2” that were never tested against anything. Before recent large eclipses, marketplaces were flooded with cheap imports carrying copied certification text, copied logos and copied test-report numbers. Printing a standard number on a card frame costs nothing.

You cannot reliably detect a counterfeit by eye. The lamp test above will catch the crudest fakes, but a filter that is dark enough in visible light can still pass too much infrared, and you have no way of measuring that at home. The defence is therefore not inspection but provenance.

Buy from an established astronomy retailer, telescope dealer, science museum, planetarium or optics manufacturer with a name and a trading history, ideally in your own country.
Prefer suppliers who name the manufacturer of the filter material, not just the printer of the cardboard. A small number of firms make the polymer and coated-glass filter stock used worldwide; reputable sellers say whose material they use.
Be very wary of general online marketplaces and third-party resellers, where the seller is anonymous, the listing is one of two hundred identical ones, and the reviews are for a different product entirely. This is where fakes circulate.
Treat glasses given away free at an unrelated promotion, or included as a bonus with an unrelated purchase, with the scepticism they deserve unless you can trace the source.
If a national astronomical society or your local science museum publishes a list of vetted suppliers before the eclipse, use it. Such lists have been maintained for previous eclipses and are the single best shortcut.

Handheld solar viewers and welder’s glass of shade 14 (some experienced observers accept shade 13 for brief use, and nothing below that) are alternatives to cardboard glasses, and a mounted, purpose-made white-light solar filter from a telescope manufacturer is the most robust option of all.

Cameras, binoculars and telescopes: the filter goes on the front

This is the mistake that causes the most severe injuries, so it gets its own section.

Any optical instrument gathers light over the whole area of its front lens or mirror and concentrates it into a beam a few millimetres across. A modest 80 mm telescope collects roughly 130 times as much energy as your dilated pupil. That beam will set paper alight. Directed into an eye, it destroys retina instantly and irreversibly.

Never use an eyepiece-end solar filter

Small screw-in “sun filters” that fit the eyepiece of cheap telescopes sit at the focus of all that concentrated heat. They crack without warning, sometimes after only a minute or two, and when they do there is nothing between the beam and your eye. If one came with your telescope, throw it away. The solar filter must always cover the full aperture at the front, so that the dangerous light never enters the instrument in the first place.

Doing it properly

Fit a full-aperture white-light solar filter — coated polymer film or coated glass sold for the purpose — over the objective end of every telescope, spotting scope, camera lens and each barrel of your binoculars.
Make sure it cannot fall or be blown off. Tape it, or use a filter cell with a positive lock. Desert wind and a filter held on by friction alone is a bad combination.
Cap or remove the finder scope. Finders are miniature telescopes and cause their own burns; people forget them because they are not looking through them.
Filters go on before the instrument is pointed anywhere near the Sun, and come off only after it has been pointed away — or, during totality, in the controlled way described below.
For camera work specifically, see our eclipse photography guide: the filter also protects the shutter and sensor, and a bare telephoto lens aimed at the Sun can damage the camera as well as the photographer.

Watching without looking: projection methods

Indirect viewing is completely safe, needs no certified equipment, works brilliantly for groups, and is by far the best way to keep a large number of children occupied during the long partial phases. In every case you stand with your back to the Sun and watch an image on a surface.

Pinhole projection. Punch a small, clean hole in a piece of card with a pin. With the Sun behind you, hold the card up and let the light fall on a second white card a metre or so away. The little disc of light is an image of the Sun, and during the partial phases it is a crescent. Larger separation gives a bigger, fainter image. Never look at the Sun through the hole.
A kitchen colander held up in the sunlight throws dozens of crescents at once onto the ground or a sheet. So does a cheese grater, a straw hat, a cracker, or your own fingers held in a loose lattice.
Tree shadows. The gaps between overlapping leaves act as thousands of pinholes. Under an acacia or a palm on 2 August, the ground will be carpeted with crescents. In Upper Egypt look for this on pale stone and paving, where the contrast is highest — the temple courts and hotel terraces will be covered in them.
Binocular or telescope projection. Mount the instrument, cap one barrel of the binoculars, aim it using its own shadow rather than by sighting, and let the image fall on a white card held 30–50 cm behind the eyepiece. This gives a large, bright, sharply focused Sun that a whole group can watch at once. Two cautions: never put your eye to the eyepiece while it is projecting, and do not leave a cheap instrument projecting continuously for more than a minute or two, as heat can damage cemented eyepiece elements.

Supervising children

Children are the group most at risk, and the fix is supervision rather than instruction.

Assume glasses will be pushed up, pulled off, worn upside-down or peered around. One adult should be responsible for one or two children throughout the partial phases, with no other job.
Check the fit. Adult-sized card frames slip on small faces; look for child-sized viewers, or add a strap, or have the adult hold the filter in front of the child’s eyes.
Give younger children an indirect method as their primary activity and treat the glasses as an occasional, supervised extra. Crescents on the ground hold attention for far longer.
Explain the plan for totality in advance, and give a clear verbal command — “glasses OFF now” and later “glasses ON now” — rather than expecting a child to judge the moment.
If you are travelling with a group, agree who calls those two commands before you leave the hotel. It should be one person, watching the Sun, with a watch.

The exception: during totality, take the glasses off

Everything above is about protection. This section is about the opposite, and it matters just as much, because a great many people travel across the world to a total eclipse and then watch the most beautiful sight in nature through a filter that renders it completely invisible.

During totality — and only during totality — it is safe to look at the eclipsed Sun with the unaided eye. It is also necessary. Through eclipse glasses you will see nothing at all, because the corona is roughly as bright as a full Moon and the filter is designed to block a hundred thousand times more light than that. The corona, the pink chromosphere, the prominences, the planets, the 360° sunset around the horizon: all of it is invisible through a solar filter and all of it is safe to view directly. Binoculars, too, are safe and spectacular during totality — provided their filters are removed and then replaced at the right moments.

How to time it

Keep the glasses on through the whole approach. In the last minute the light goes strange, shadows sharpen, and the temperature drops noticeably.
The final sliver of Sun breaks into Baily’s beads — points of light shining through valleys on the Moon’s limb — then merges into a single brilliant point: the diamond ring. Glasses stay on for this.
When the diamond ring goes out, take the glasses off. That is second contact. The sky is dark, the corona is out, and there is no bright photosphere left to hurt you. Cameras and binoculars come off filter now too.
Watch. This is what you came for.
At the first flash of the second diamond ring, on the opposite edge of the Moon, the glasses go straight back on — and filters go back on every instrument. Do not wait to see how it develops. That flash is the returning photosphere, and it goes from harmless to hazardous within a second or two.

A useful discipline: know your third-contact time to the second, and set a phone or watch alarm for about 20 seconds before it. Then you are never caught watching a rising brightness and wondering whether it has started. The times below are computed for the town centres; a few kilometres of movement shifts them slightly, so use the interactive map to check your exact site.

Local times (EEST, UTC+3) on Monday 2 August 2027. Glasses come off at the start of totality and go back on at the end — not a second later.
Where	Glasses off	Glasses on	Naked-eye window
Luxor	13:02:03	13:08:24	6m 20s
Sohag	12:58:44	13:05:06	6m 22s
Qena	13:01:32	13:07:43	6m 11s
Bahariya Oasis	12:50:16	12:56:33	6m 17s
Marsa Alam	13:08:02	13:13:31	5m 29s
Aswan (99.8% partial)	—	—	None — filters on throughout

Why Egypt makes this easier, not harder

Short totalities are stressful. When you have 90 seconds, every action competes with every other one, and the temptation is to rush the transitions at either end. The 2027 eclipse gives Upper Egypt up to 6 minutes 23 seconds on the central line near Sohag — the longest totality visible from land between 1991 and 2114, and around 50% longer than the 4m 28s maximum of the 2024 North American eclipse. Compared with the 1m 48s available in Spain in 2026, it is a different kind of event entirely.

That length is a safety asset. There is time to take the glasses off calmly after the diamond ring has clearly gone, time to look, time to raise binoculars, time to take a photograph, time to put the camera down — and, crucially, time to stop, re-fit filters and be ready well before third contact. Use the generosity. Give yourself the last thirty seconds with nothing in your hands, and put the glasses on the moment the light returns.

Wedjat — the Eye of Horus

The ancient Egyptians drew the wedjat, the restored eye of Horus, as a symbol of wholeness, protection and healing — and used its parts as fractions. It is a fitting emblem for a day when the Sun goes out over Thebes: look after your own eyes, and they will give you six minutes you remember for the rest of your life.

Eye safety questions

The questions that come up most often before a total eclipse.

Is it really safe to look at totality with no filter at all?

Yes. During totality the Moon covers the Sun’s bright photosphere completely, and what remains — the corona — is about as bright as a full Moon. It is astronomically safe to view with the naked eye, with binoculars or through a telescope. This is not a fringe opinion; it is the consensus of every professional astronomical and ophthalmological body. The care required is entirely in the timing: filters off only after the first diamond ring has gone out, and back on at the first flash of the second one.

How dark is dark enough? Can I test my glasses at home?

You can rule glasses out at home but you cannot confirm them. Held up to a bright domestic lamp, a compliant filter shows you the filament faintly and nothing else — no room, no furniture, no hands. If you can see anything of your surroundings, the glasses are not solar filters. Passing that test, however, says nothing about infrared transmission, which is why buying from a reputable astronomy supplier matters more than any test you can do yourself.

Are my old eclipse glasses from 2017 or 2024 still usable?

Filters made to ISO 12312-2 from good-quality coated polymer or glass do not have a fixed shelf life, and the once-common “discard after three years” advice has been withdrawn by the main manufacturers. What matters is physical condition. Inspect them in bright light for pinholes, scratches, creases and any lifting of the coating, check the film is still sealed to the frame, and discard them if there is any doubt at all. Given how little they cost relative to a trip to Egypt, taking new pairs as well is sensible.

Can I look through my camera, phone or binoculars during the partial phases?

Only with a proper solar filter fitted over the front of the optics. Never with eclipse glasses held against the eyepiece — the concentrated beam melts the film almost instantly. An optical viewfinder is as dangerous as looking directly. An electronic viewfinder or rear screen does not endanger your eyes, but an unfiltered telephoto lens pointed at the Sun can damage the camera’s shutter and sensor. See the photography guide.

Aswan is 99.8% covered. Surely that is close enough to take the glasses off?

No. The remaining 0.2% of the photosphere is still tens of thousands of times brighter than the corona and will damage your retina exactly as the full Sun would. Obscuration percentages are misleading in this respect: the safety question is binary, not gradual. Either the photosphere is completely hidden or it is not. If you are in Aswan, Hurghada, Cairo or anywhere else outside the path, filters stay on for the entire eclipse — or, better, drive into the path, which from Aswan means as little as 15 km.

What if I accidentally glance at the partly eclipsed Sun?

A brief, involuntary glance of a fraction of a second is what your blink reflex is for, and is unlikely to cause lasting harm. Deliberate staring is the danger. If afterwards you notice blurring, a central blind spot, distorted straight lines, altered colours or a persistent after-image, see an eye-care professional as soon as possible — symptoms often appear some hours later. Do not assume that feeling nothing at the time means nothing happened; the retina cannot register pain.

Do I need special sunscreen, hats or protection for my skin as well?

Yes, and people badly underestimate this. Totality falls near 13:00 with the Sun around 80° overhead in early August, when Nile-valley temperatures typically reach 40–43°C. You will be outdoors for two to three hours. High-factor sunscreen, a wide-brimmed hat, loose long sleeves, several litres of water per person and controlled shade matter as much as your eye protection. See plan your trip and our weather guide.

Someone is selling “eclipse glasses” cheaply online. How do I judge them?

Judge the seller, not the product. Buy from an astronomy retailer, telescope maker, planetarium or science museum with a real trading identity, ideally one that names the manufacturer of the filter material. Avoid anonymous marketplace listings, which is where counterfeits with copied ISO wording circulate before every major eclipse. If a national astronomical society publishes a list of vetted suppliers ahead of 2027, buy from that list.

Plan your eclipse trip Photographing totality Where to watch

Eclipse Eye Safety