On August 21, a total solar eclipse will cross the United States from coast to coast for the first time since 1918.

The historic event is expected to draw record crowds, as millions of people will be in or close to the path of totality, where viewers can see the moon completely blot out the sun for more than two minutes.

Before the main event, find out how much you know about eclipses, from the science behind the spectacle to the historic and cultural connotations.