American solar eclipse 2017: What is an eclipse, how can you watch it and what will the weather be?

On Monday, August 21 the sun, moon and Earth will line up in an act of cosmic serendipity that will turn day into night across the 2,680-mile width of the United States. It will be the first time that has happened in nearly a century, and never will a total solar eclipse be so heavily viewed and studied. From Oregon in the west, to South Carolina in the east, there will be festivals and flamboyant eclipse viewing parties. And of course, traffic gridlock, an social media explosion, and general ch