How to Watch a Solar Eclipse Safely

There is nothing else in the sky quite like it. For a few minutes the Moon slides fully across the Sun, day drops to a deep blue dusk, the temperature falls, and the Sun’s ghostly corona blazes out around a black disk. People plan trips years ahead and cry when it happens. It is worth every mile.

It is also the one target in all of astronomy that can permanently blind you, silently, in the time it takes to say so. The Sun is safe to look at with the naked eye for exactly one window — the brief totality of a total eclipse — and dangerous every other second, including every moment of a partial or “ring of fire” eclipse. Get the gear right and you’re free to just watch. This guide is how you get it right.

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The one rule: whatever you look through, the solar filter goes over the front and must meet ISO 12312-2. Certified eclipse glasses for your eyes; a front-mounted filter for any binoculars or telescope. Sunglasses, phone cameras, smoked glass and old screw-in “sun” eyepiece filters are not safe and never will be.

The only safety standard that matters: ISO 12312-2

Any filter you point at the Sun — glasses, a binocular filter, a telescope filter — should state that it meets ISO 12312-2, the international standard for direct solar viewing. It guarantees the filter blocks essentially all of the visible light plus the invisible ultraviolet and infrared that also cook your retina. A proper white-light solar filter transmits about 1 part in 100,000, so the Sun shows up as a comfortable, sharp disk. If a product doesn’t actually name the standard, don’t trust your eyes to it, no matter how dark it looks.

For your eyes: certified eclipse glasses

For most people, watching an eclipse means standing in a field with a paper pair of eclipse glasses and looking up. That’s the whole kit, and it’s enough — the partial phases, when the Moon slowly covers the Sun, are the part everyone remembers, and glasses show them perfectly. Buy a pair for everyone in your group, and buy them early: certified glasses are made in seasonal batches around eclipses and reliably sell out in the weeks beforehand. Check each pair before use for scratches or pinholes, and toss any that are damaged. Check price on a certified pair ▸

If you own binoculars

A magnified view turns dark sunspots and the crisp edge of the Moon’s bite into something you can really study. The safest way to get it is a dedicated solar binocular like the Celestron EclipSmart, which has ISO 12312-2 filters built into the objectives and permanently sealed — nothing to attach, align, or knock loose at the worst possible moment. You can also fit certified front filters over binoculars you already own, but that puts the whole safety burden on you. Our solar binoculars guide covers both routes in depth, including how to filter a pair you own safely.

Never hold eclipse glasses in front of or behind binoculars or a telescope. The glasses are rated for your naked eye, not for the concentrated light coming out of a 42mm lens — that combination can let intense light through and injure you. Filter the front of the optics, or use the glasses alone with no magnification.

If you own a telescope

A telescope shows the Sun’s disk larger and sharper than anything else, with sunspot groups resolved in detail — but it also gathers the most light, so the filter has to be right. Use a front-mounted, ISO 12312-2 white-light solar filter sized to your telescope’s aperture; it caps the big end of the tube so the sunlight is blocked before the optics ever concentrate it. Two rules that are not optional: the filter goes on the front, never at the eyepiece, and it must be sized to your scope, so match the model to your aperture before you buy. Old screw-in eyepiece “sun” filters sit where the light is focused and hottest, can crack without warning, and belong in the bin. Check price on a front solar filter ▸

What never to use

None of these block the infrared that silently burns your retina, and none belong anywhere near your eyes or your optics: sunglasses (even several stacked), smoked or tinted glass, exposed camera film or X-ray film, CDs or DVDs, Mylar balloon material, a phone or camera pointed at the Sun without a proper filter, or welding glass below shade 14. When in doubt, if the product doesn’t print “ISO 12312-2” on it, it isn’t solar-viewing gear.

The one moment the filter comes off: totality

During a total solar eclipse, and only in the brief minutes when the Moon completely covers the Sun, it is safe to lower the glasses and look with the naked eye — and the corona hanging in a dusk-dark sky is the sight people travel the world for. The instant the first blinding sliver of the Sun’s surface reappears, the glasses go straight back on. If any part of the bright disk is showing, you need the filter. A partial eclipse and an annular (“ring of fire”) eclipse never have a safe unfiltered moment — the Sun’s surface is exposed the entire time, so the filter stays on from first contact to last.

The next solar eclipse: August 12, 2026

The next total solar eclipse is August 12, 2026. The path of totality crosses Greenland, western Iceland, and a sliver of northern Spain — the first total solar eclipse over mainland Europe since 2006, which makes it a travel eclipse for most of us rather than a backyard one. A partial eclipse is visible across much of Europe, and a modest partial reaches parts of the far northeastern U.S. and Canada low in the evening sky. If you’re chasing totality, Iceland and northern Spain are the destinations — and stargazing- or eclipse-viewing tours in those regions book up early.

After that, mark August 2, 2027: a total eclipse over southern Spain, North Africa (including Egypt) and the Arabian Peninsula, with up to 6 minutes 23 seconds of totality — the longest over land until 2114. For viewers in the contiguous United States, the next total solar eclipse after April 2024 doesn’t come until 2044, which is exactly why a set of certified glasses and a filter for your optics is worth owning now: there are partial eclipses, sunspots, and planetary transits to watch in the meantime. Our eclipse guide has the full calendar of solar and lunar eclipses through 2030, with a live countdown and where each one is visible.

The bottom line

Watching a solar eclipse safely comes down to three pieces of gear and one rule. Certified ISO 12312-2 eclipse glasses for your eyes cover almost everyone — buy a few pairs and buy them early. Add solar binoculars or a front-mounted solar filter for your telescope if you want a magnified, detailed view. And whatever you do, keep the filter over the front and on the Sun at all times, except during the brief totality of a total eclipse. Do that, and you’re free to stop worrying and just watch one of the great sights of your life. New to observing the Sun in general? Start with our guide to viewing the Sun safely.