The total solar eclipse on August 21 will be the first time many Americans will directly see the moon entirely blocking out the disc of the sun. But with our animation you can catch an early preview of the "Great American Eclipse."
Zooming out from the earth's surface, we pan over to the moon in orbit. As the moon slides in front of the sun, it appears as if our lunar satellite is taking larger and larger cookie bites out of the fiery solar surface.
At the moment of "totality," when the moon entirely obscures our home star, irregularities in the lunar terrain such as mountains, valleys and canyons become visible as "Baily's beads," and the sun's corona -- its mysterious, always present but rarely visible atmosphere -- shines bright like a spectacular crown.
Altering our perspective, the view swings around to reveal how the moon casts its shadow on earth: both the 'penumbra' (the zone of partial shadow) and the 'umbra' (the zone of complete shadow). The eclipse shadow makes first contact in the Pacific Ocean. Zooming in on North America, the eclipse shadow races eastward, to make landfall in the Pacific Northwest.