The "Great American Eclipse," as it is being called, will move diagonally across the country, northwest to southeast, providing a spectacular solar show -- again, weather permitting -- and an excellent excuse for scores of eclipse-viewing parties and music festivals.

It will first be visible in the northwestern state of Oregon at 9:05 am (1605 GMT), with totality there coming 75 minutes later. Oregon authorities say they expect a million people to flood into the state for the event, clogging roadways and overflowing campgrounds, the Oregonian newspaper reported.

In all, about 12 million people living in 14 states will be in the path of totality, with many million others able to witness at least a partial eclipse, according to the American Astronomical Society.