Rating is available when the video has been rented.
This feature is not available right now. Please try again later.
Uploaded on Dec 13, 2010
Ocean tides rise and fall twice a day, influenced by the gravitational forces of the sun and moon. Studying tides' rhythmic movements helps us understand both the ocean and the cosmos. Astronomer Ben Burress explains how tides work, and QUEST visits Crissy Field in San Francisco to see the oldest continually operating tidal gauge in the Western Hemisphere.