On Monday, August 21, there will be a total solar eclipse visible in a band across the entire contiguous United States. The last time that happened was in June of 1918. In fact, the last time a total solar eclipse was visible anywhere at all in the continental U.S. was in 1979. So, this is a big deal for American eclipse watchers and millions of us will be heading for some part of the 65-mile-wide band of totality that wends its way from Oregon to South Carolina.