We all know that we should never look directly at the Sun. It’s tempting to look directly at an eclipse during the partial phases because, well, there’s not as much Sun showing. But a partial eclipse is just as damaging to your eyes as looking at the unobstructed Sun.

The notable exception to this rule is during totality, those few minutes when the Sun is completely blocked by the Moon. In Bloomington, Indiana, this will happen for four minutes on April 8, 2024.

Starting a few seconds before 3:05 pm the Moon will move in front of the Sun, completely blocking the light from it. This will be totality and will last until until a few seconds before 3:09 pm. During this time, and only during this time, it is safe to remove your viewers and directly observe the eclipse. And indeed, it is the only way to directly view totality because with all of the Sun’s light blocked, you won’t be able to see anything through your viewer.

Dr. Hin Cheung, professor of Optometry, explains the particular vulnerabilities of our eyes to the bright light of the Sun, and how to make sure you are staying safe while eclipse-viewing.