TEMPO.CO, Jakarta – Millions of people across Europe will have the chance to witness a rare solar eclipse on Wednesday, August 12. While certified solar-viewing glasses are the safest option for looking directly at the Sun, ordinary sunglasses are not suitable for eclipse viewing.
Ordinary sunglasses typically block only around 80 to 90 percent of visible light, while safe direct viewing of the Sun requires reducing the amount of light reaching the eye by roughly 99.999 percent.
The safest option is ISO 12312-2-compliant solar-viewing glasses or a handheld solar viewer specifically designed for looking directly at the Sun.
However, an ISO number printed on a product does not automatically guarantee its safety. Counterfeit solar glasses are available online, so viewers should buy them from reputable suppliers and check the filters for scratches, tears or other damage before use.
If ordinary objects are clearly visible through the glasses indoors, they should not be used for solar viewing.
How to Use Eclipse Glasses
Put the solar-viewing glasses on before looking toward the Sun and remove them only after turning away.
Children should be supervised while watching the eclipse, particularly if the glasses do not fit securely.
Most importantly, never look at the Sun through binoculars, telescopes or camera lenses while wearing eclipse glasses.
These devices concentrate sunlight and can damage the filter and the eyes. Any optical equipment used for solar observation needs a specialized solar filter securely fitted over the front of the instrument.
No Eclipse Glasses? Try These Safe Methods
If certified solar-viewing glasses are unavailable, viewers can still watch the eclipse indirectly by projecting an image of the Sun onto another surface.
According to ITV, here are three simple ways to watch the eclipse safely if you don't have eclipse glasses:
1. Make a Pinhole Viewer
A simple pinhole viewer requires two pieces of card and a pen or pencil.
Make a small hole in the center of one piece of card. Stand with your back to the Sun and hold the card up, with a second piece of white card positioned behind it.
Sunlight passing through the hole will project a small image of the Sun onto the second card. As the Moon moves across the Sun, the projected image will gradually appear as a crescent.
Do not look through the hole toward the Sun.
2. Use a Colander
A kitchen colander can also be used as a simple eclipse projector.
With your back to the Sun, hold the colander so its shadow falls onto a white piece of paper or another light-colored surface. Each hole acts like a tiny pinhole projector, creating multiple images of the Sun.
During the eclipse, the normally round projections will appear as crescents. The method can produce dozens of images at once, making it particularly useful for groups watching the event together.
3. Make a Dark-Box Viewer
A cardboard box can be turned into a basic projector using a few household items.
You will need a cardboard box, white paper, aluminum foil, scissors, a pen and tape or glue.
Attach the white paper to one side of the inside of the box. On the opposite side, make two openings, one for viewing and another for the pinhole. Cover the pinhole with aluminum foil and make a tiny hole in the foil.
With your back to the Sun, look through the viewing opening. Sunlight entering through the pinhole should project an image of the Sun onto the white paper inside the box.
The dark interior can make the projected image easier to see.
Why Direct Sunlight Can Damage Your Eyes
Looking directly at the Sun can cause solar retinopathy, in which intense light damages the retina at the back of the eye. The injury may not cause immediate pain, while symptoms such as blurred or distorted vision or a dark spot in the center of vision can emerge hours after exposure.
Some people recover over weeks or months, but the damage can sometimes be permanent.
For those without certified eclipse glasses, indirect projection methods such as a pinhole viewer, colander or dark-box projector offer a safer way to experience the eclipse.
The key rule is simple: keep your back to the Sun and watch its projected image rather than looking directly at it.
Where and When Can It Be Seen?
The path of totality will cross northern and central Spain, as well as parts of Portugal, Greenland and Iceland. Much of Western Europe, including the UK, France, Belgium, Switzerland and northern Italy, will experience a partial eclipse.
In London, the partial eclipse is expected to begin at about 6:17 p.m. BST, reach its maximum at around 7:13 p.m., and end at approximately 8:06 p.m.
Because the Sun will be low on the horizon, astronomers recommend finding a location with an unobstructed view toward the west, away from buildings and trees.
The amount of the Sun covered will vary significantly by location. Cornwall is expected to see around 96 percent coverage, while western Scotland will see about 93 percent and London about 92 percent.
