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.)
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