Sky gazers across Mexico and the United States are preparing for a historic total solar eclipse on April 8. It will be the last total solar eclipse that will be visible from the contiguous U.S. until August of 2044.
Anyone who plans to try to view the eclipse should be extremely careful since it can take as little as one to three seconds for the powerful rays of the sun to cause permanent burns in the eyes, according to Dr. Marc Mathias, a retina specialist who cares for both children and adults on the Anschutz Medical Campus in Aurora.
“There is no safe amount of time to view the sun without protection,” said Mathias.
How can I stay safe if I want to see the total solar eclipse on April 8?
If you’re planning to check out the April 8 eclipse, follow these simple guidelines to protect your eyes:
- View the eclipse only with special eclipse sunglasses.
- Do not rely on regular sunglasses. They are NOT safe for viewing the eclipse.
- Keep eclipse sunglasses on at ALL times during eclipse viewing (except during totality when you can remove eye protection briefly). But this is only visible along a narrow band that will stretch from Texas toward the northeastern U.S. and only lasts about three to four minutes. If you are unsure of whether or when totality is occurring, do not remove your eclipse sunglasses.
- Be sure to provide all children with eclipse sunglasses and be sure they do not remove them during the total solar eclipse.
- If you experience vision loss after viewing an eclipse, please see your nearest retina specialist for evaluation.
To help those who plan to view the eclipse, Mathias answered common questions about the sun and eye safety.
Why are our eyes so vulnerable to burns?
Looking at the sun without protection is very dangerous because the front of the eye is essentially like a magnifying glass, Mathias said.
“The front structure in our eyes acts like a camera system or a magnifying glass to focus light,” said Mathias. “The retina is the light sensitive tissue that lines the inside part of our eye that’s connected to our brain.”
Think of when you were a child, and you used a magnifying glass to burn a leaf on a sidewalk.
“The sun’s rays are very, very powerful,” said Mathias, who is an associate professor of ophthalmology at the University of Colorado School of Medicine and cares for patients at both UCHealth University of Colorado Hospital and Children’s Hospital Colorado.
“When we look at the sun, the rays are undergoing that some kind of focus that occurs through a magnifying glass, and it’s being focused on our retina,” he said. “In a very, very short time — a matter of as little as one to three seconds — it heats up and essentially causes a burn or a hole to the light-sensitive tissue.”
Have you cared for patients who have harmed their eyes during an eclipse or by looking directly at the sun?
Yes, Mathias has cared for many patients over the years who have suffered eye damage from looking directly at the sun.
You never want to look straight at the sun whether there’s an eclipse or not, Mathias said.
He has treated both children and adults who have suffered eye damage from what eye doctors call “solar retinopathy.”
Some children dare one another to look directly at the sun, and that’s how they get injured.
So it’s vital for parents to teach their children never to look directly at the sun and to keep a close eye on them if they’re venturing out to view an eclipse.
“Young children are not aware of the danger, so parents need to make sure their children are supervised and that they are wearing their glasses properly and keep them on for the entire time when they are looking directly at the sun during the eclipse,” Mathias said.
Other patients who have suffered solar damage have included people with psychiatric disorders or those with an altered mental state, like those who look directly at the sun while impaired by drugs or alcohol.
How do people know if they have eye damage from viewing an eclipse?
“In the weeks after an eclipse, we’ll frequently see patients who are complaining of different visual symptoms,” Mathias said. “Often, they’ll have a blind spot in the central part of their vision. We call that a central scotoma.”
Mathias said people can lose a significant amount of vision in the center of their eyes very quickly.
“And during a partial solar eclipse, that damage is often in a crescent shape,” he said. Patients will say they have blind spot.
Is eye damage from viewing an eclipse temporary or permanent?
Unfortunately, Mathias said the damage from solar retinopathy often is permanent.
“The retina is an incredible structure in the body, but it doesn’t have the ability to heal itself very well once it has suffered significant injuries,” Mathias said.
“With more serious injuries, there’s typically not a significant recovery. That’s why we are very, very adamant about educating people. It only takes a few seconds for damage to occur if people are looking at the sun and forget to wear eclipse glasses. It can happen very, very quickly and can cause permanent damage,” he said.
Where can I get glasses that are safe for viewing the eclipse? I hear it’s common for poor-quality eclipse glasses to circulate in advance of an eclipse.
It’s true that people have to be very careful about which eclipse glasses they use, Mathias said.
He said it’s vital to make sure your glasses are stamped with the following code: ISO 12312-2. This indicates they are manufactured to strict international standards and are NASA-approved.
The American Astronomical Society has created a list of approved eclipse glasses, viewers and filters.
Another great source for safe eclipse glasses is your local natural history museum or planetarium. The Denver Museum of Nature and Science, for instance, sells eclipse glasses through its museum store. Some free glasses are also available through the Smithsonian’s National Air and Space Museum. Check out your local museum or library for more information. And try these fun eclipse activities from the Smithsonian that you can enjoy anywhere.
In addition to getting eclipse glasses from a trusted source, Mathias said it’s also vital to carefully examine the glasses before using them. That’s because they have a thin film.
“You do not want any sort of defect. No matter the source of the glasses — even those from a good manufacturer — you always want to inspect the glasses to make sure there’s no damage to the surface. There’s shouldn’t be any scratches, tears, rips or dings in the surface,” he said.
If I have the right eclipse glasses, is it safe to look through a camera while wearing the glasses?
No. Do not wear solar eclipse glasses to look through a camera, binoculars or a telescope, as the sun can melt the filter and damage your eyes. The device can condense the light and make it even stronger.
Instead, people who are trying to capture images of an eclipse need to use special solar filters on your cameras, binoculars and telescopes. If you are not certain whether you have the right equipment, leave the photography to the professionals.
“It’s never safe to look through any optical device, even with eclipse glasses on,” Mathias said. “That’s the recommendation from all of the manufacturers of eclipse glasses and from the American Academy of Ophthalmology.
What if I want to capture photos of an eclipse through my phone?
Using your phone should be safer, but it may be hard to see through your eclipse glasses to take good photos. Enjoy the eclipse and let professionals with proper solar filters on their gear take the photos.
What is totality, and can I take my eclipse glasses off during totality?
Inside the area where the total solar eclipse will be visible, the eclipse will cause temperatures to drop rapidly, will create an eerie darkness in the middle of the day and will create a beautiful array of colors from the sun’s atmosphere.
The path of totality is the area where the moon will completely cover the sun. The path will pass over the Pacific Coast of Mexico at about 11 a.m. local time, then will arc to the northeast throughout the afternoon on April 8, stretching from Texas through Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire, and Maine. Small parts of Tennessee and Michigan will also experience the total solar eclipse. People in Colorado will only be able to see a partial eclipse. Many eclipse super fans will be traveling to areas where they hope to find clear skies so they can experience the full effects of the eclipse.
It is safe to remove your eclipse glasses, but only if you’re in the path of totality and only for a short time, Mathias said.
“If you are within the path of totality, you can remove your eclipse viewing glasses during that time, and you can briefly look at the sun if it’s completely blocked,” Mathias said.
“As soon as any light from the sun comes back into view, you need to put your eclipse glasses back on.”
How long will ‘totality’ last during the April 8 total solar eclipse?
Depending on where you try to view the eclipse and how cloudy the weather is, the phase known as totality will last between three and four minutes. (To learn all about totality and how long it will last, check out this interactive map from NASA.)
I hear total solar eclipses are rare. Is that true?
Yes, total solar eclipses are very rare. The last one that was visible from the United States took place in 2017 and was the first that was visible here since 1979. After the April 8, 2024 event, eclipse enthusiasts will have to wait 20 more years if they wish to witness a total solar eclipse from the U.S.
The 2024 solar eclipse won’t be visible from Colorado, but do people who live at higher elevations need to be especially careful when viewing an eclipse or when they’re spending time outdoors. Is the sun more powerful at higher elevations?
Elevation doesn’t make any difference when it comes to keeping your eyes safe during an eclipse, Mathias said. No matter where you are, you need to protect your eyes.
But the sun is more powerful all the time at high elevations. So, just like you want to take extra measures to protect your skin by regularly wearing sunscreen at higher altitude, you also want to protect your eyes all the time. It’s an excellent idea to wear sunglasses, Mathias said. And, of course, never, ever look directly at the sun.