On Monday, August 21, 2017, a total solar eclipse will be visible in totality within a band across the entire contiguous United States, and will only be visible in other countries as a partial eclipse. The previous time a total solar eclipse was visible across the entire contiguous United States was during the June 8, 1918 eclipse.
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometers wide.