[Found in "Q & A on the News", San Jose Mercury News,
03 October 1993]
Time zones were established because railroads needed a standard
for timekeeping at various points so timetables for operating trains
could be prepared. Without time zones in which each community kept
the same time, each town would use local solar time...and no two towns
would agree on a common time. The potential for confusion - and
collisions - was large.
India, Burma, Afghanistan, Iran, central Australia, Surinam,
Newfoundland and several island nations observe time zones that
differ from neighboring zones by a half-hour. Nepal is even more
unusual -- it's five hours and 45 minutes ahead of Greenwich Mean
Time, or 15 minutes ahead of India.
By international agreement, the Earth is divided into 24 time zones, each
envisioned as 15 degrees wide -- though countries can carve out whatever
time zones they please. In the center of each zone, theoretically, the
sun is overhead at noon. But at the boundary of two zones, the sun would
be overhead at 11:30 a.m. or 12:30 p.m. Because of this, a country on a
boundary is more in sync with solar time by choosing a time a half-hour
off. Most of the countries with staggered time zones are located close
to a boundary or straddle one.
For simplicity's sake, many countries keep only one time, even though
they're larger than one time zone -- most notably China, which straddles
five zones but keeps Beijing time nation-wide. Iran, Afghanistan, India
and Burma all straddle two zones, with their centers more or less at the
boundary. By choosing the odd time, they split the difference.
As for central Australia, it was put a half-hour behind eastern
Australia, rather than a full hour, because of its business links
to the east.
How to explain Nepal? Or Newfoundland, which distances itself by a half
hour from neighboring provinces? In many cases a country or territory
chooses the odd time to underscore its independence and to be different
from its neighbors.