It's already being called the Great American Eclipse, and it's coming on August 21, 2017. For the first time in 38 years, the shadow of a total solar eclipse will cross the lower 48 of the United States. If you have seen a partial solar eclipse and think there is no reason to see a total one, think again. In a partial eclipse, you must use those little cardboard pinhole viewers to see the sun's disk projected onto a piece of paper so as not to hurt your eyes. It's very cool, but not the transformative experience of a total eclipse, when the apparent diameter of the moon is larger than that of the sun and blocks all direct sunlight. Day turns to night, birds go silent, and you can stare directly at the moon with the sun behind it without any eye protection. (You still have to be careful though! Cover your eyes before the sun re-emerges. Here's a complete guide to eclipse eye safety from NASA.) - One Year From Now, America Will See Its First Total Solar Eclipse Since 1979 Cool.