Q: Since the sun rises in the east and sets in the west, how is it that the Aug. 21 total solar eclipse begins in Oregon and ends in South Carolina, west to east?
—David Dickey, Dallas
A: The west-to-east motion of the eclipse is due to the direction in which the moon's shadow moves across the Earth, Fernbank Science Center astronomer Mark Lancaster told Q&A on the News via email.
The Earth rotates eastwardly, Lancaster wrote, which causes the sun and moon to rise in the east and set in the west each day. This also causes shadows to be cast westward in the morning and to move toward the east in afternoon hours.
“However, the moon is also moving in an eastward direction as it orbits the Earth — but at a much greater speed than Earth is rotating,” he wrote.
The moon’s shadow “drags” behind it as it moves, he added.
Like a normal everyday shadow, the moon’s shadow will move from west to east, forming the eclipse. Lancaster said the eclipse will move from the West Coast of the United States to the East Coast in just an hour and 33 minutes on Aug. 21.
Fast Copy News Service wrote this column; Joe Youorski contributed. Do you have a question? We’ll try to get the answer. Call 404-222-2002 or email q&a@ajc.com (include name, phone and city).
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