Eye safety is RING OF FIRE EXPEDITIONS’ main priority at any observational event involving the Sun. For decades I have provided safety information to people in various countries as well as appearing on TV and giving interviews to the local press prior to and during our solar eclipse expeditions. This has been a critical part of the international outreach of the NASA Johnson Space Center Astronomical Society.
While it is difficult to look/stare at the full sun, the eye has no evolutionary mechanism to pull away from viewing a deep partial phase, where the sunlight is considerably weaker yet still very dangerous!
Proper eclipse observing protocols are important to provide to people in general who are not familiar with astronomy or observation of the Sun at any time. Education is a critical element and it is incumbent on eclipse organizers to bring that knowledge and disseminate it early to avoid problems including eye injury.
Even in modern times there are people in authority who will provide misinformation based on ignorance or who have political agendas. The photo to your right is an example of an ophthalmologist in Australia prior to the November 2012 Total Solar Eclipse in Cairns. This person is advising local people not to look at the Sun during totality and during the partial phases of the eclipse even with approved eclipse viewing glasses. However, this warning is mis-informed and incorrect. There can be no excuse for an irresponsible recommendation like this.
Your eyes are precious commodities and must not only be protected from the blinding brightness of sunlight in the visual spectrum but also that from the ultraviolet and infrared. Although watching a solar eclipse or planetary transit across the Sun can be an amazing experience, you must exercise great caution to avoid retinal damage as a result or improper observation techniques. Because the eyes have no pain receptors, prolonged staring at the sun could easily result in retinal damage.
Prolonged staring (or even relatively short looking) at the sun is dangerous because the eye concentrates sunlight just like a magnifying glass does with subsequent, strong, heating focused to a point.
In addition, guidance on the type of ‘safe’ solar filter devices may vary internationally due to political, technical and/or social factors related to the country. The following information is based on decades of observational experience by RING OF FIRE EXPEDITIONS.
In the photo to your left ,three different safe methods are shown. Left: telescope with solar filter mounted in front of the lens; center: observer uses a #14 welder’s glass; right: observer uses binoculars with mylar filters in front of the lenses.
While we concentrate on solar observing during eclipses, there is also similar concern when attempting to see the ‘green flash’ at sunset or sunrise (or other times) since you must ‘see’ the Sun to be sure it is in your field of view for photography. For videography and even photography, the situation is made safer in that if your camera/camcorder is securely pointed and mounted, you can use the screen to keep the camera pointed and focused, thus avoiding the need to visually look through a set of optics.
SAFE METHODS for observing the Sun
Observing the Sun can be inherently dangerous but there are ways that eclipse observation can be accomplished safely and without risk.
THE ONLY TIME WHEN YOU CAN SAFELY LOOK DIRECTLY AT THE SUN WITHOUT ANY FILTER PROTECTION IS DURING THE BRIEF PERIOD OF A TOTAL SOLAR ECLIPSE WHEN ALL OF THE SUN’S LIGHT IS BLOCKED. If you are unsure when this will occur, stay close to our tour escort who will signal when it is safe. This ‘free pass’ DOES NOT APPLY for an annular eclipse, partial eclipse, transit of Mercury or Venus across the sun or daily observation of the Sun when none of these phenomena are scheduled.
As a general precaution, never leave any of the following devices unsupervised especially when there are children about. This can be especially true in foreign countries where communication with locals can be problematic.
UNSAFE METHODS to view the sun
The following methods you must avoid since they pose a significant hazard to your eyes or to those of someone who might wander up to your instrument. Some of these methods may appear safe at first use but they are not!