Portugal's free eclipse glasses are gone. A €3 certified pair does exactly the same job
The 12 August eclipse will cover between 92% and 99% of the Sun over mainland Portugal. Ciência Viva's free bookings sold out again, but certified glasses are on sale — and three markings have to be printed on them.
The free glasses for the 12 August eclipse have sold out again. Ciência Viva topped up the stock, demand ate through it a second time, and anyone who reached the Clube da Visão platform late is now a week from the event with nothing to look through.
That is not a reason to give up. Certified glasses are on sale in pharmacies, supermarkets and some online shops for about three euros, and they are the identical product.
What has to be printed on the glasses
Three markings, worth checking before you pay: the ISO 12312-2 standard, the CE mark, and a reference to Regulation (EU) 2016/425. Without those you are holding expensive sunglasses that make a promise they cannot keep.
The warning from Ciência Viva is blunt. Looking at the Sun unprotected can burn the retina, distort vision temporarily and cost you sight permanently. The frightening part is that none of it hurts while it is happening — the damage sets in without any alarm, and people only notice afterwards.
There is a second warning that gets less attention: your phone will not enjoy it either. Pointing a phone camera or a stills camera straight at the Sun without a proper solar filter can wreck the sensor. These devices were never built for that much light.
How much you will actually see
Totality is confined to a narrow strip of Montesinho Natural Park, near Bragança. Everywhere else on the mainland it is a partial eclipse, with between 92% and 99% of the Sun covered. In the Azores and Madeira the figure falls to somewhere between 74% and 77%.
Bragança council has moved its official viewing event out of the villages of Rio de Onor and Guadramil to the municipal aerodrome because of wildfire risk. The science and culture programme survives the move intact, and the new site still gets 99% coverage — almost everything, though not the full darkness the villages were in line for.
It is worth sitting with how rare this is. The last total solar eclipse seen from Portugal was in 1912, and the next one is not due until 2144. The same date also brings the Perseid peak under a new moon, which makes 12 August the best day of sky a whole generation is going to get.
Image: Wikimedia Commons (public domain)
