This Wednesday is setting up to be a blockbuster day for skywatchers across the world as a total solar eclipse will steal the show for millions who are lucky enough to see it. On Aug. 12, Northern Russia, Greenland, Iceland, Northern Spain, and a small corner of Portugal will see complete darkness in the path of totality. A total solar eclipse occurs when the moon passes between the sun and Earth, completely blocking the sun's light, according to NASA. During this event, the sky will briefly darken as if it were dawn or dusk. Parts of the U.S. will see only about 10% coverage of the solar eclipse, stretching from Alaska to North Carolina, where people can view the moon taking a small bite out of the sun.