EDIT: THE CONTENTS OF THIS POST ARE ESPECIALLY TRUE FOR THE PATH OF TOTALITY. DO NOT LOOK AT THE ECLIPSED SUN WITHOUT PROTECTION NO MATTER HOW ECLIPSED IT IS.
Kinda crazy to think about the fact that weâre basically guaranteed to have a wave of people with eye damage because they didnât know (as I didnât until a few minutes ago) that looking at the eclipsed sun is more dangerous than looking at it normal-ways.
Apparently this is because the lower light level causes your pupils to dilate, which lets in more of the sunâs UV than normal (UV being the part that actually causes eye damage).
Maybe this is more common knowledge than I thought, but it still canât hurt to say that YOU SHOULD NOT EVEN GLANCE AT THE ECLIPSE WITHOUT PROPER EYE PROTECTION. Even a glance can cause permanent damage!
According to NASA's Eclipse Viewing Safety page, you can look safely at the eclipse without protection and see the sun's corona
ONLY during full, complete totality
but seeing even a LITTLE of the sun's uncovered photosphere through dilated irises can do some homestuck style shit to your eyes.
more info confirming safety of looking without a viewer during totality from the National Solar Observatory, the American Association of Opthamologists and the American Astronomical Society
If you look at it through a viewer during totality, you won't see the sun's corona, which is dim enough to be invisible at all other times. That's the part that looks cool. If you have a viewer, you can remove it when you can no longer see anything through it.
if you're gonna look and you don't have a viewer, make a pinhole camera to see when it's safe and look away well before it's uncovered and puts a permanent spot on your retina
Edit: there's an eclipse timer app that uses geolocation to tell you when to take your glasses off and put them back on, with a $1.99 in-app purchase for this eclipse: for iOS and android
there's also "the eclipse app". more apps listed here and here
