On August 21, 2017, an event will happen across parts of the Western Hemisphere that has not been seen by most people in their lifetimes. A total eclipse of the Sun will sweep across the face of the United States and nearby oceans. Although eclipses of this type are not uncommon across the world, the chance of one happening near you is quite small and is often a once-in-a-lifetime event unless you happen to travel the world regularly. This year, the total eclipse will be within driving distance of most people in the lower 48 states.