Hin Cheung, Indiana University Bloomington – How to Safely View a Total Solar Eclipse

On Indiana University’s Total Solar Eclipse Week: Safety is always key when it comes to the sun.

Hin Cheung, clinical assistant professor at the School of Optometry, explains how to view the eclipse without causing damage to your eyes.

Dr. Hin Cheung joined the Indiana University School of Optometry in July 2021 as a clinical assistant professor in primary care services at the Atwater Eye Care Center. Aside from clinical teaching, Cheung also teaches first-year ocular biology and serves as the coordinator of the primary care residency program.

He completed his undergraduate studies at University of Waterloo in 2010 and received his Doctor of Optometry with distinction from Ferris State University Michigan College of Optometry in 2014. He then completed his residency in ocular disease at Indiana University School of Optometry, followed by a Ph.D. in vision science in 2021 while working part time as an adjunct clinical lecturer teaching students in the clinic.

How to Safely View a Total Solar Eclipse

While a total solar eclipse is a truly an amazing sight to experience, it’s never safe to look directly at the sun without proper protection. Looking directly at the sun can potentially cause lifelong consequences and damage to your eyes and vision.

The best way to protect your eyes during a solar eclipse is to view it indirectly by looking at a projection of the sun or a shadow of the eclipse. You can do this by using a pinhole projector. One simple way to do this is by interlacing your fingers and making a waffle pattern, and with the sun behind you, project the image of the sun on the ground. Another easy way is to look at the shadows of leaves under a tree.

You can also view the eclipse directly using a special eclipse viewer. Unlike sunglasses, these viewers have special filters that block out harmful levels of light and radiation from the sun and allow only a small fraction through the filter which makes it safe for solar viewing. However – be cautious to avoid fake or fraudulent eclipse viewers. If you want to purchase your own, avoid online marketplaces that are not on the endorsed list of vendors from the American Astronomical Society. There will be specific labeling that says “ISO 12312-2” on the viewer that marks it in compliance.

If you are in the path of totality for the April 8 solar eclipse, this will be the only time it’s safe to look at the sun without protection because the moon completely covers the sun during totality. The closer you are to the center of the path of totality, the longer totality will be, which may last up to about four minutes. The moment you notice any level of sunlight coming through towards the end of totality, put your viewers back on to protect your eyes.