Laura Bott, age 10, of College Park, Georgia, for her question:

How many time zones are there all together?

Every calendar day, the noon sun passes from east to west, inching all the way around the world. The times zones of the globe mark off each hour of the sun's daily travel time. And naturally, it takes 24 of them to do the job. They are planned to follow the lines of longitude that run from pole to pole, but since people set their clocks by the time zones, straight lines would be inconvenient in some places. If a zone line ran through Atlanta, for example, the clocks in the eastern part of town would be set an hour earlier. So the world's 24 zone lines zig and zag around populated areas.

Zone 0 swoops down from the North Pole to cover England, parts of Spain and Africa and then tapers on down to the South Pole.

From the zero zone,l1zones are counted westward and 11 are counted eastward. They meet at zone 12 in the mid Pacific  and here we cross the International Date Line where each new calendar day begins. When the noon sun crosses the Date Line, the clocks in zone 0 strike midnight. When the noon sun reaches zone 0, the clocks of Atlanta say 7 a.m. Atlanta is in time zone 5, counting westward from zone zero.