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. Soluna’s 2-pack is made in the USA by American Paper Optics, the NASA-approved manufacturer on the AAS supplier list; for a family or group, the certified 6/12/24-packs below beat buying two-packs. Only buy from makers you can verify on the AAS supplier list — counterfeits are common, and a printed ISO number on its own proves nothing. Made-in-USA 2-pack ▸

A closer look, no gear to set up: 2× power viewers

If flat eclipse glasses feel like too little but binoculars are more than you want to fuss with, 2× power viewers are the easy middle. They’re folding handheld viewers — the same certified ISO 12312-2 solar film as good glasses, but with a small 2× lens behind it, so the growing bite out of the Sun and the bigger sunspot groups show sharper and larger. Nothing to mount, nothing to align, and safe to hand a kid. The honest catch this season: Celestron’s EclipSmart 2× pair — the one we’d point you to — has been out of stock since mid-July, and certified viewers are made in seasonal batches that rarely restock in eclipse week, so there’s no listing here we can stand behind right now. If you find a pair in a shop, check the film for pinholes and scratches like any pair of glasses. For a magnified look you can actually buy today, the sealed-filter EclipSmart solar binoculars below are the pick. Same rule as ever: a power viewer is for your naked eye only — never hold one in front of binoculars or a telescope.

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 the northeastern U.S. and eastern Canada around midday to mid-afternoon — up to about a fifth of the Sun covered from New England, glasses on the whole time. If you’re chasing totality, Iceland and northern Spain are the destinations, and stargazing- or eclipse-viewing tours in those regions book up early.

Here’s the reason to circle the date even if you can’t chase totality: August 12 is a rare triple-header. The very new moon that blacks out the Sun also leaves the sky as dark as it gets for the Perseid meteor shower, which peaks that same night — the best Perseid conditions in years, and visible from any dark backyard with no filter and no plane ticket. Step outside before dawn and you can catch the other half: a six-planet parade strung low across the morning sky. For most of us the eclipse itself is a partial or a flight abroad — but the meteors and the planets are a free show over the same 24 hours.

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.