On August 21, 2017, millions of people across the United States will see nature's most wondrous spectacle — a total eclipse of the Sun. It is a scene of unimaginable beauty; the Moon completely blocks the Sun, daytime becomes a deep twilight, and the Sun’s corona shimmers in the darkened sky. This is your guide to understand, prepare for, and view this rare celestial event.

A total solar eclipse is unlike anything you've seen in your life. As totality approaches, you will see the astonishing sight of day turning to night and the Sun's corona blazing in the sky. This is truly a great American eclipse because totality will sweep the nation from the Pacific to the Atlantic. Nearly everyone in the US can reach this total solar eclipse within one day's drive.  An eclipse is a cosmic billiard shot — the Sun, Moon, and Earth line up to reveal the Sun's atmosphere, it's corona. Eclipses on Earth occur only because of an amazing celestial coincidence.