Watching Eclipses Safely: When You Can Look at the Sun and When You Never Can

Few sights in the sky are as striking as a solar eclipse, and few are as easy to enjoy the wrong way. The Sun does not stop being dangerous to look at because the Moon covers part of it. NASA's rules for watching are short, and there is only one moment when you can look without protection.

This guide goes through those rules: the one moment that is safe, the tools NASA says work, what does not work, how to watch with no special gear and what the Bench task shows. It follows NASA's eclipse viewing safety page, last updated on March 20, 2026, and an older eye-safety paper on NASA's Goddard eclipse site. It does not recommend any brand, shop or product.

The one rule

NASA states the rule in one sentence. Except during the brief total phase of a total solar eclipse, when the Moon completely blocks the Sun's bright face, it is not safe to look directly at the Sun without specialized eye protection for solar viewing. NASA's Goddard glossary says the same thing from the other side: the only time the Sun can be viewed safely with the naked eye is during a total eclipse, when the Moon completely covers the disk of the Sun.

The rule depends on the type of eclipse, so the table below goes moment by moment.

How will you know totality has started? NASA says you will know it is safe when you can no longer see any part of the Sun through your eclipse glasses or solar viewer. As soon as even a little bit of the bright Sun reappears, put the glasses back on or use the viewer again.

Safe tools: eclipse glasses and handheld viewers

For a partial or annular eclipse, NASA says to look through safe solar viewing glasses, called eclipse glasses, or a safe handheld solar viewer at all times. Use this checklist before you look:

• They are not sunglasses. NASA says regular sunglasses, no matter how dark, are not safe for viewing the Sun.
• They meet the standard. Safe solar viewers are thousands of times darker and ought to comply with the ISO 12312-2 international standard.
• No brand is endorsed. NASA does not approve any particular brand of solar viewers.
• They are undamaged. Inspect the viewer before use and discard it if it is torn, scratched or otherwise damaged.
• Children are supervised. NASA says to always supervise children using solar viewers.

NASA's Goddard paper gives the benchmark for a safe solar filter. It should let through less than 0.003 percent of visible light and no more than 0.5 percent of near-infrared radiation.

Watching without special gear

If you do not have eclipse glasses or a handheld viewer, NASA says you can use an indirect method that does not involve looking at the Sun. One way is a pinhole projector. It has a small opening, for example a hole punched in an index card, and it projects an image of the Sun onto a nearby surface. With the Sun at your back, you look at the projected image. NASA's eclipse FAQ says indirect methods are always appropriate for observing the Sun.

NASA describes a box projector made from a cardboard box, a white sheet of paper, tape, scissors and aluminum foil. Sunlight streams through a pinhole in foil taped over a hole in one side of the box, and you look into the box through another hole to see a crescent Sun on the paper. NASA's eclipse guide adds that sunlight shining through the holes in a colander or a straw hat, or between the fingers of crossed hands, also makes crescent images, as do leaf shadows under trees.

The Goddard paper says the screen should be at least a meter behind the opening to get an image large enough to see easily. It also says care must be taken that no one looks through the device. NASA's own warning is plain: never look at the Sun through the pinhole.

Cameras, binoculars and telescopes

Optics concentrate sunlight, so they get their own rules. NASA says viewing any part of the bright Sun through a camera lens, binoculars or a telescope without a special-purpose solar filter secured over the front of the optics will instantly cause severe eye injury.

• Filters go on the front. NASA says solar filters must be attached to the front of any telescope, binoculars, camera lens or other optics.
• Eclipse glasses stay off the optics. NASA says not to use eclipse glasses or handheld viewers with cameras, binoculars or telescopes. The concentrated rays will burn through the filter and cause serious eye injury.
• Get advice. NASA says to seek expert advice from an astronomer before using a solar filter with any optical device.
• Avoid filters that screw into eyepieces. The Goddard paper calls the filters often supplied with inexpensive telescopes unsafe, because they can crack from overheating, and injury can occur faster than you can move your eye away.

The Goddard paper adds that a local planetarium, science center or amateur astronomy club can give more information on how to observe an eclipse safely.

What does not work, and why it hurts

The Goddard paper lists materials it calls unsafe: all color film, black-and-white film that contains no silver, photographic negatives with images on them, smoked glass, sunglasses worn singly or in several pairs, photographic neutral density filters and polarizing filters. It says most of them let through high levels of invisible infrared radiation that can burn the retina.

The injury is quiet. The paper explains that the retina has no pain receptors, so retinal injuries occur without any feeling of pain, and the visual effects do not appear for at least several hours after the damage is done. It says failure to use proper methods may cause permanent eye damage or severe loss of vision, and that most people with eclipse-related eye injuries are children and young adults.

Neither a dim Sun nor a lack of discomfort proves safety. The paper says the fact that the Sun looks dim, or that you feel no discomfort, is no guarantee that your eyes are safe. NASA's glossary adds that even when 99 percent of the Sun's surface is covered, the remaining crescent can cause permanent retinal damage, especially through binoculars or other optical aids.

Your skin needs care too. NASA says the Sun is very bright during the partial phases, and if you watch a whole eclipse you may be in direct sunlight for hours, so wear sunscreen, a hat and protective clothing.

Common mistakes

• Using sunglasses as eclipse glasses. NASA says they are not safe, no matter how dark.
• Taking glasses off during a partial phase because the Sun looks dim. A dim look is no guarantee of safety.
• Treating the annular ring as the safe moment. The Sun is never completely blocked in an annular eclipse, so NASA says it is never safe to look without protection.
• Wearing eclipse glasses behind a telescope or camera. The glasses are not made for optics, and NASA says the concentrated rays will burn through the filter.
• Looking through the pinhole. The projector shows you an image. You look at the image, not at the Sun.
• Using scratched or torn glasses. NASA says to discard them.
• Leaving children unsupervised with solar viewers.
• Waiting too long to put the glasses back on after totality. The first bit of bright Sun means the glasses go back on.

Try it in the instrument

Open the Alignment Bench and set the sky to a partial solar eclipse with the Moon below the plane. In the Bench's side view the shadow passes under Earth's center. Only the Moon's penumbra touches Earth, and no one on Earth sees totality.

Three settings produce it.

1. Phase: New Moon. Solar eclipses only occur at a New Moon, according to NASA.
2. Height: below the plane, but within the eclipse zone. Fred Espenak of NASA's Goddard Space Flight Center writes that if the New Moon takes place within about 17 degrees of a node, a solar eclipse will be visible from some location on Earth. NASA's eclipse maps call an eclipse central, meaning total, annular or hybrid, if the shadow axis passes within 0.997 Earth radii of Earth's center. That limit works on both sides, north and south, so a Moon below the plane behaves like one above it. Past the central limit, the axis misses Earth. Farther out, the umbra and antumbra completely miss it.
3. Result: partial everywhere. NASA's eclipse tables define a partial eclipse as one where only the penumbra crosses Earth.

This is why the safety rule matters. Totality is the only safe moment, and totality needs the umbra to reach you. In this setting it never does, so there is no moment to take your viewer off. Compare it with the total solar eclipse, where the umbra does reach Earth. The Bench is a simplified model with a range of accepted heights, so it teaches the relation and does not forecast real eclipses.

Questions people ask

Is it ever safe to look at a solar eclipse without eye protection?

Only during the brief total phase of a total solar eclipse, when the Moon completely blocks the Sun's bright face. At every other moment of every other kind of eclipse, NASA says to use proper eye protection or an indirect method.

Can I use regular sunglasses to watch an eclipse?

No. NASA says regular sunglasses, no matter how dark, are not safe for viewing the Sun. Safe solar viewers are thousands of times darker and ought to comply with the ISO 12312-2 standard.

How do I know totality has started?

NASA says you will know it is safe when you can no longer see any part of the Sun through your eclipse glasses or solar viewer. When bright sunlight reappears, put them back on at once.

Can I wear eclipse glasses and look through binoculars or a telescope?

No. NASA says not to use eclipse glasses or handheld viewers with cameras, binoculars or telescopes. Those devices need their own solar filters, attached to the front.

What can I do if I have no eclipse glasses?

Use an indirect method, such as a pinhole projector with the Sun at your back. Never look at the Sun through the pinhole.

Sources

• Eclipse Viewing Safety, NASA Science. https://science.nasa.gov/eclipses/safety/. Opened November 9, 2026.
• Annular Eclipse Safety, NASA Science. https://science.nasa.gov/eclipses/future-eclipses/eclipse-2023/safety/. Opened November 9, 2026.
• Total Solar Eclipse Safety, NASA Science. https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/safety/. Opened November 9, 2026.
• What to Expect: A Solar Eclipse Guide, NASA Science. https://science.nasa.gov/feature/solar-eclipse-guide/. Opened November 9, 2026.
• Eclipses Frequently Asked Questions, NASA Science. https://science.nasa.gov/eclipses/faq/. Opened November 9, 2026.
• Eye Safety During Solar Eclipses, NASA Goddard Space Flight Center, Eclipse Web Site (B. Ralph Chou, University of Waterloo School of Optometry). https://eclipse.gsfc.nasa.gov/SEhelp/safety2.html. Opened November 9, 2026.
• Glossary of Solar Eclipse Terms, NASA Goddard Space Flight Center, Eclipse Web Site (Fred Espenak). https://eclipse.gsfc.nasa.gov/SEhelp/SEglossary.html. Opened November 9, 2026.
• Key to Solar Eclipse Maps, NASA Goddard Space Flight Center, Eclipse Web Site (Espenak and Meeus). https://eclipse.gsfc.nasa.gov/SEcat5/SEmapkey.html. Opened November 9, 2026.
• Periodicity of Solar Eclipses, NASA Goddard Space Flight Center, Eclipse Web Site (Fred Espenak). https://eclipse.gsfc.nasa.gov/SEsaros/SEperiodicity.html. Opened November 9, 2026.

We opened each source ourselves on the date shown. The drawings are our own and were checked against the numbers in these sources.

Read next

• Partial Solar EclipseA partial solar eclipse happens when only the Moon's outer shadow, the penumbra, reaches Earth, so the Sun is covered in part and never fully.
• Annular Solar EclipseAn annular solar eclipse happens when the Moon is at or near its farthest point, so it looks smaller than the Sun and leaves a bright ring.