How to Observe the Sun Safely

7 min read

Key facts

Golden rule	Never look at the Sun without a proper solar filter
Naked-eye viewing	Eclipse glasses or handheld viewers meeting ISO 12312-2
Telescopes and binoculars	A dedicated solar filter covering the front opening
Safest indirect method	Pinhole projection
What you can see in white light	Sunspots, faculae and granulation
What H-alpha shows	Prominences, filaments and flares
Best time	Morning, when the air is often steadier and cooler
Solar activity	Cycle 25 is past its peak as of 2026, but sunspots are still common
Never use	Sunglasses, smoked glass, film, CDs or eyepiece sun filters

In short

Looking at the Sun, even briefly, can permanently damage your eyes, and the injury is painless, so you may not notice until later.
For looking with your eyes alone, use only eclipse glasses or handheld viewers that meet the ISO 12312-2 standard.
ISO 12312-2 covers naked-eye viewing only; never use eclipse glasses behind binoculars, a telescope or a camera.
Telescopes and binoculars need a dedicated solar filter that covers the front of the instrument before sunlight enters it.
Pinhole projection is a simple, free and safe way to watch the Sun, especially during an eclipse.

Why the Sun is dangerous

The Sun is so bright that staring at it focuses intense light onto the retina, the light-sensitive layer at the back of the eye. This can cause solar retinopathy, a burn that may leave a permanent blind spot. The retina has no pain sensors, so you will not feel it happen.

Binoculars and telescopes make the danger far worse. They gather much more light than your eye and focus it to a point, which can cause instant, permanent damage and even melt or crack parts of the instrument.

The good news is that safe solar viewing is easy with the right tools. The rule is simple: never point your eyes or any optics at the Sun without a proper solar filter.

Eclipse glasses and handheld viewers

For naked-eye viewing, use eclipse glasses or handheld solar viewers that meet the international standard ISO 12312-2. They block more than 99.99% of sunlight and nearly all harmful ultraviolet and infrared light. Through them, the Sun looks like a comfortable orange or white disk and everything else is dark.

Buy from a reputable supplier; the American Astronomical Society keeps a list of checked sources. Before each use, inspect the filters for scratches, holes or loose lenses, and throw away damaged ones. Put them on before looking up, and look away before taking them off. Supervise children closely.

Remember that ISO 12312-2 applies only to viewing with your eyes. It is not a rating for telescope or binocular filters, and eclipse glasses must never be used behind any optics. The concentrated light will burn through them in moments.

Pinhole projection

Projection lets you watch the Sun without looking at it. Make a small hole in a piece of card, stand with your back to the Sun and let sunlight pass through the hole onto a second card or the ground a few feet behind. You will see a small, round image of the Sun.

A kitchen colander, crossed fingers or the gaps between tree leaves work the same way, and during a partial eclipse they cast dozens of tiny crescents. Pinhole images are too small to show much detail, but they are completely safe as long as you never look at the Sun through the hole.

White-light filters for telescopes

To see sunspots up close, a telescope or binoculars need a solar filter made for that purpose. It must fit securely over the front opening, so it cuts the light down before it enters the optics. Filters are made of special coated glass or thin optical film and should come from a dedicated solar-filter maker for astronomy.

Never use the small screw-in sun filters once supplied with some cheap telescopes. They sit near the eyepiece where the light is focused, and they can crack without warning. Also cover or remove the finder scope, and never leave a telescope pointed at the Sun unattended.

Some refractor owners use a Herschel wedge, a special diagonal that dumps most of the light. It must be used only with refractors and with the extra filters it comes with. If you are unsure, use a front-mounted filter.

What you can see

In white light, the Sun shows sunspots, dark cooler regions where strong magnetic fields hold back heat. They change from day to day, and over a week or two you can watch them cross the disk as the Sun rotates. Near the edge you may see brighter patches called faculae, and steady skies can show a fine grainy texture called granulation.

A hydrogen-alpha (H-alpha) telescope passes only a very narrow band of red light from hydrogen. It shows prominences, glowing loops and arches at the Sun's edge, along with dark filaments and the occasional flare. These instruments are specialized and must be built for solar use from the start.

Solar Cycle 25 passed its peak around late 2024. As of 2026 activity is declining, but sunspots are still frequent, so it is a good time to start.

Never improvise

Sunglasses, even very dark ones, are not safe. Neither are smoked glass, stacked sunglasses, exposed photographic film, CDs, X-ray film or welding glass unless it is shade 14 or darker. Phone screens and cameras do not protect your eyes either, and pointing an unfiltered camera at the Sun can damage its sensor.

The only time it is safe to look at the Sun without a filter is during the brief totality of a total solar eclipse, when the Moon completely covers the Sun's bright face. Put your filter back on as soon as the first bright point reappears. See our eclipse guide for details.

If you ever have blurred vision or a blind spot after looking at the Sun, see an eye doctor promptly. With proper filters and a little care, the Sun becomes one of the most rewarding objects to observe.