How Do Time Zones Fit In?
Each time zone is an hour earlier than the one east of it and an hour later than the one west of it. But Earth rotates to the east on its axis at a rate of one degree every 4 minutes (15 degrees in an hour). So the sun appears overhead in eastern parts of the time zone before it does in western locations.

    Try This! Find Houston, TX, on this time zone map. Then find San Antonio, TX. Watches in both cities would say 9:00 because they are in the same time zone. In which city would a shadow stick clock (sundial) show 9:00 first? (Answer below map.)

    Answer: A shadow stick clock (sundial) in Houston would show 9:00 first because it is east of San Antonio. (The sun would pass over it first.)

    More! Houston is at about 95 degrees W longitude. San Antonio is at about 98 degrees W longitude. The distance between them is 3 degrees longitude. A sundial in Houston would show 9:00 (Local Apparent Time) about 12 minutes before the sundial in San Antonio. (3 degrees longitude X 4 minutes per degree = the time difference.)