SAN ANTONIO – On April 8, 2024, parts of San Antonio and the Hill Country will be in the path of a rare total solar eclipse.
So, you may be wondering about how you can safely view it.
Remember those eclipse glasses from last fall’s annular eclipse? You’ll need another pair.
The 411 on the viewing glasses
For people in the path of totality, the moon will completely block the sun for a short time. This will be the only time that it will be safe to look directly toward the sun.
At all other times, it’s necessary to wear specialized eye protection designed for solar viewing. Even when 99% of the Sun’s surface is obscured, the remaining sun is still intense enough to cause retinal burn, experts say.
Before you buy a pair of eclipse-viewing glasses, make sure you check the safety authenticity to ensure the glasses meet the basic proper viewing standards that NASA recommends on its website.
Eclipse glasses and hand-held solar viewers should meet all the following criteria:
- Have certification information with a designated ISO 12312-2 international standard.
- Have the manufacturer’s name and address printed somewhere on the product.
- Not be used if they are more than three years old, or have scratched or wrinkled lenses.
- Viewers of the eclipse should not use homemade filters or ordinary sunglasses — not even very dark ones — because they are not safe for looking directly at the sun.
NASA’s partner, the American Astronomical Society, has verified manufacturers that are making eclipse glasses and hand-held solar viewers that meet the ISO 12312-2 international standard. You can check out the full list on their website.
Several stores are also selling certified solar viewers including Home Depot, Lowes and Walmart.
The American Astronomical Society says modern eclipse glasses with the ISO 12312-2 designation do not expire as long as they have no punctures, scratches or tears, and the filters/lenses remain attached to the frames.
Are there any alternatives to the glasses?
You could try a pinhole projection if you want to see the eclipsed sun. The easy-to-make device helps you avoid looking directly at the eclipse by using a projected image.
Otherwise, the only safe way to look directly at the uneclipsed or partially eclipsed sun is through special-purpose solar filters, such as the eclipse glasses, or hand-held solar viewers. Homemade filters or ordinary sunglasses, even very dark ones, are not safe.
The Texas Optometric Association said welder’s glass and Mylar filters are also an option.
“Number 14 welder’s glass provides effective protection and can be found at a local welder’s supply store. This glass will reduce the harmful rays that are emitted during the eclipse. Do not use if there are any scratches or damage to the glass.”
“Aluminized Mylar plastic sheets are available as eclipse vision glasses or can be cut and made into a viewing box. Do not use if there are any scratches or damage to the sheet.” the TOA said in a press release.
What NOT to do:
It’s unsafe to look at the sun through an unfiltered telescope or binoculars because optical instruments intensify the light.
Here are some other things NOT TO DO during the eclipse according to the Texas Optometric Association:
- Do NOT use your smartphone: Watching a solar eclipse on your smartphone camera can put you at risk of accidentally looking at the sun when trying to line up your camera. It could also damage your smartphone camera.
- Do NOT use your camera viewfinder: Never look at a solar eclipse through the optical viewfinder of a camera. It can damage your eyes in the same way as looking directly at it.
- Do NOT use unsafe filters: Unless specifically designed for viewing a solar eclipse, no filter is safe to use with any optical device (telescopes, binoculars, etc.). All color film, black-and-white film that contains no silver, photographic negatives with images on them (x-rays and snapshots), smoked glass, sunglasses (single or multiple pairs), photographic neutral density filters and polarizing filters are unsafe filters to watch a solar eclipse. Solar filters designed for eyepieces that come with inexpensive telescopes are also unsafe.
A few ground rules
- Always inspect your solar filter before using it. If you find it’s scratched or damaged, don’t use it. Read and follow any instructions printed on or packaged with the filter. Always supervise children.
- Stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the sun. After glancing at the sun, turn away and remove your filter. Don’t remove it while looking at the sun.
- Do not look at the sun through an unfiltered camera, telescope, binoculars or other optical device. Similarly, do not look at the sun through a camera, a telescope, binoculars or any other optical device while using your eclipse glasses or hand-held solar viewer. The concentrated solar rays will damage the filter and enter your eyes, causing injury.
On April 8, 2024, the path of a rare total solar eclipse will pass through Texas, including parts of San Antonio and the Hill Country around 1:30 p.m.
The Northwest quadrant of San Antonio will experience totality for one-to-two minutes while parts of the Hill Country will get totality for up to four minutes.