It's one of the most talked about astronomical events of the century—a total solar eclipse.
Just after 9 a.m. PDT, a solar eclipse will make its way across the continental U.S., from Oregon to South Carolina. Viewers within the path of totality—a thin, 70-mile-wide swath—will see the moon completely eclipse the sun. Those to the north and south of the path of totality will see partial eclipses. (Learn how to watch the solar eclipse from anywhere.)
This rare alignment, in which only the sun's corona is visible, hasn't been seen across the continental US since 1918, and a record number of people are flocking to states where they can see totality.
A total solar eclipse happens somewhere on Earth once every year or two. What is an eclipse? Learn more about how solar eclipses happen, the four types of eclipses, and how to view the sun safely if you're within the path of totality.
Eclipse map adapted with permission: https://www.exploratorium.edu/eclipse
Header Image: The moon almost totally eclipses the sun during a near total solar eclipse as seen from Salem, Oregon. PHOTOGRAPH BY DON RYAN, AP