A rare total solar eclipse will cross parts of Spain and Portugal on 12 August, offering a sunset totality but requiring strict eye protection.
The glowing cosmic phenomenon of the total solar eclipse on August 12 will be visible to millions of people in Greenland, Iceland, northern Russia, Spain, and Portugal. This is the first of three eclipses expected over Spain in the next two years. The most reliable way to prepare for safe viewing is to have a pair of eclipse glasses. Sunglasses do not protect the eyes during direct observation of the event.
A solar eclipse occurs when the Moon passes between the Earth and the Sun, completely covering its disk. Since the total eclipse will pass over Spain in the evening, observers will be able to witness a rare ‘sunset’ eclipse: after the total phase, the Sun will reappear above the horizon as a thin disk that gradually disappears.
Those whose path of totality does not cross fully will see a partial solar eclipse – the Moon will shade only part of the Sun. Such a partial eclipse will pass through the northern United States, Canada, most of Europe, and northwestern Africa. Check the event time on TimeandDate.com to find out when it will occur in your region.
“Even 1% of the Sun’s surface that remains visible radiates enough radiation to cause permanent damage to the eye’s light-sensitive cells,”
– Institute of Astrophysics of the Canary Islands
“Direct viewing of the Sun can lead to blindness or vision impairment.”
– NASA
How to safely observe the eclipse
To view the phenomenon without risking your sight, use the following observing options:
- eclipse glasses, certified to ISO 12312-2; or a portable solar viewer;
- a telescope, binoculars, or camera with a front solar filter – they work just like glasses.
Sunglasses do not replace eclipse glasses or solar viewers, which are 100,000 times darker and meet international safety standards. Although sunglasses protect against harmful ultraviolet radiation in everyday use, they are not designed for direct observation of the Sun.
The eclipse-viewing lenses are made from black polymer or resin with carbon particles that block almost all visible, infrared and ultraviolet rays, according to The Planetary Society. Sunglasses do not block infrared radiation.
To find reputable manufacturers of eclipse glasses and filters for optical devices, including cameras and smartphones, refer to the list compiled by the American Astronomical Society (AAS).
Put on eclipse glasses before you raise your gaze to the Sun, and look away from the Sun before removing them. Keep an eye on children – do not allow them to remove the glasses during observation.
If you normally wear prescription glasses, keep them on and wear eclipse glasses over them, or use a handheld viewer as recommended by the AAS.
Do not view the Sun through an unfiltered optical device – camera lens, telescope or binoculars – while using eclipse glasses or a handheld viewer; solar rays can penetrate the filter and cause serious eye damage, NASA warns.
Welding filters can also be used for safe viewing; many consider shade numbers 13 or 14 to be best. Filters with shade number 12 or higher allow safe viewing, but such filters are rarely available in stores – they can be found online, according to the AAS. The Sun may appear green instead of yellow-orange or white.
DIY or adjustable welding helmets are not recommended for viewing, as they may not reduce the light quickly enough to protect the eyes.
Provided that the glasses or viewers meet the ISO 12312-2 standard and have no tears, scratches or other damage, they have no expiration date and can be used for a long time. There is also no limit on the duration of viewing the Sun through such devices.
Store the glasses and viewers for future eclipses, keeping them at room temperature in a case or in their original packaging to avoid scratches.
Do not use water, glass cleaners, or wet wipes to clean eclipse glasses – moisture can ruin the frame. Instead, gently wipe the lenses with a cloth or a soft wipe.
If certified glasses are unavailable, you can observe the eclipse individually using a pinhole projector, for example, a hole in a card. It works when you stand with your back to the Sun and hold up the card. The pinhole projects an image of the partial Sun onto the ground or another surface.
Do not look directly at the Sun through a pinhole; do not use it as the primary observing method. Other simple pinhole projectors – bowls, colanders, or other objects with small holes – can also help you see the phases of the eclipse through shadows on a surface. You can also use your hands, spreading your fingers to create a “waffle” pattern, through which the Sun is partially visible during a partial eclipse; gaps between leaves will produce fragments of the eclipse phase shadows.
Plan for safe viewing and protect your vision during this remarkable cosmic event.