Solar eclipse safety of of utmost importance! You should never look directly at the Sun, even during a total eclipse if the Moon hasn’t fully blocked out the Sun. Click for up-to-date eclipse-viewing guidance from NASA.

However, the advice given on how to safely view an eclipse, as well as what equipment people can use, has changed throughout history – we’ll talk about some of these below.

Pinhole camera

As the equipment used for studying  the Sun greatly improved over time, the methods deemed ‘safe’ for observing solar eclipses also went through many changes. One old method still applied today to observe a solar eclipse indirectly uses a pinhole camera. Light passes through a very small hole (the ‘pinhole’) into a dark space to project an image of the eclipse in this device.

Although this concept was described in different ways by Chinese philosopher Mozi and by Greek philosopher Aristotle in the 5^th and 4^th centuries BC respectively, it wasn’t until the Islamic Golden Age that the concept was put into practice. It was during the 11^th century AD that scientist Ibn Al-Haytham (sometimes also known as ‘Alhazen’) produced the first pinhole camera, which was later called a ‘camera obscura’. Using this invention, Al-Haytham was able to successfully observe and study solar eclipses.

How a pinhole camera works. An image can be created of the real object by the light from the object projecting onto the film. The image of the object appears upside-down. Credits: Kyle Simek, University of Arizona

Smoked glass

President Calvin Coolidge and his wife Ms Grace Coolidge observe the 1925 total eclipse using a blackened windowpane, from the lawn of the White House, Washington, DC. Image Credit: Library of Congress, Prints & Photographs Division, photograph by Harris & Ewing, [reproduction number LC-DIG-hec-44779]

In terms directly viewing a solar eclipse, smoked glass was once a popular piece of equipment to use for apparently protecting one’s eyes from the glare of sunlight. It’s important to note that this is now deemed unsafe, and one should definitely not use smoked glass to view an eclipse! This method was recorded as first used to view the total solar eclipse of 1706 by the then King of France (nicknamed the ‘Sun King’), Louis XIV , who used a piece of this glass to cover his telescope’s objective lens.

Eclipse-o-scope glasses

Although alternate equipment was later produced for users to safely observe eclipses (such as a prism called the ‘Herschel wedge’), it wasn’t until 1932 that smoked glass was more commonly replaced by the ‘eclipse-o-scope’. This was essentially a piece of cardboard shaped a bit like an eye-mask or a pair of glasses, with ‘protective’ film covering the eye holes. Some surviving eclipse-o-scopes show that they were produced for and sold by Harvey & Lewis Co. Opticians for 10 cents, and specially made for a total eclipse observable from North America that year. Also see how eclipse viewers have changed throughout time in a collection of viewers from as early as 1793 and as late as from 2019.

Evidence of eye damage

However, evidence particularly from the late 1940s onwards showed looking at a solar eclipse through film or smoked glass was not sufficient in protecting one’s eyes from suffering any damage. An article published in 1948 described the symptoms and cause of vision problems of 32 children from a hospital in Los Angeles, after they had viewed the solar eclipse even from the previous year.

It’s possible that misconceptions about solar safety – such as the sun supposedly emitting more harmful rays during an eclipse – stem from the mid 1900’s, where more cases of eye damage from observing solar eclipses were reported. Most notably, overly extreme health warnings and perhaps unnecessary precautions were issued for some of the total eclipses during the end of the last century.

Health warnings and precautions: Australia in 1976

As preparation for the path of totality to cross over parts of Australia in 1976, countless prominent newspapers published warnings and advice from the government and the Australian Optometric Association. These newspaper articles reinforced the message that it was extremely dangerous to look (or even glance) at the Sun at any point, also and stressed that watching the eclipse through television was the only safe method. Such warnings were additionally published in other languages, such as Russian and Macedonian.

The Royal Victorian Eye and Ear Hospital in Melbourne specially organised a clinic to treat the masses of people expected to require medical assistance from viewing the eclipse. This hospital also set up a dedicated phone line for any queries about watching the eclipse or concerns about possible eye damage. In the end, only 150 people sought medical attention after the eclipse event – with only 6 deemed to have some form of minor damage to their vision. Although the Australian authorities were successful in preventing vision damage to potentially large amount of the population, many missed the chance to observe the spectacular event with their own eyes.

Health warnings and precautions: the UK in 1999

On the other side of the world over 20 years later, the UK government also gave out similarly harsh health advice for the August 1999 total eclipse. Up to 1.5 million visitors were expected to travel to Devon and Cornwall to view the total eclipse, so the local authorities were greatly concerned about their emergency services being pushed to the limits.

Warnings from the government’s chief medical officer stated that people should not look at the Sun at any point, rather, they should watch the event on television – even if they were in a location where the eclipse would be total and could be observed safely. The British Broadcasting Corporation (BBC) published articles to spread such awareness of the dangers to the public, with one attention-grabbing headline being “Eclipse cooks eyeballs”. On the other hand, associations like the College of Optometrists and the Royal College of Ophthalmologists suggested that the eclipse could be safely observed indirectly using a projection.

Perhaps over 2000 people made use of the eclipse helplines run by some of the specialist eye hospitals across the country, with most of the concerns about serious vision damage being false alarms. It’s clear that the safety warnings made by the government had overly concerned some people – for example, one tourist visiting Glasgow requested assistance because “she had not been exposed to the Scottish sun before”. In the end, the UK only recorded that around 70 people reported experiencing some damage to their vision.

Current safety advice

Although some of the safety advice above are extreme examples of precautions taken by various authorities for solar eclipse events, it is important to remember that eyes can sustain damage from looking at the Sun and that this damage can happen painlessly. Therefore, it is extremely important to protect your eyes! 

Nevertheless, a total solar eclipse is a spectacular event that is worth seeing in person if you can, rather than just through videos or television. One option is to wear modern eclipse viewers (which look a bit like 3D cinema glasses) have special material as the lenses, which reduces the brightness of the Sun’s light by 100,000 times. Alternatively, there are a variety of indirect ways to watch an eclipse –  as mentioned above, you can use a colander/sieve or even make a pinhole viewer with a cereal box!

You can learn more information about viewing a solar eclipse safely, as well as find answers to more common related questions by visiting this page or by looking at the webpages in the ‘Further Reading’ section below.