Offset Time Zones

While most of the world is familiar with time zones that differ in increments of an hour, there are many places in the world that use offset time zones. These time zones are offset by a half-hour or even fifteen minutes off of the standard twenty-four time zones of the world.

The twenty-four time zones of the world are based on fifteen degree increments of longitude. This is so because the earth takes twenty-four hours to rotate and there are 360 degrees of longitude, so 360 divided by 24 equals 15. Thus, in one hour the sun moves across fifteen degrees of longitude. The offset time zones of the world were designed to better coordinate noon as the point in the day when the sun is at its highest point in the sky.

India, the world's second-most populous country utilizes an offset time zone. India is a half-hour ahead of Pakistan to the west and a half-hour behind Bangladesh to the east. Iran is a half-hour ahead of its western neighbor Iraq while Afghanistan, just east of Iran, is an hour ahead of Iran but is a half-hour behind neighboring countries such as Turkmenistan and Pakistan.

Australia's Northern Territory and South Australia are offset in the Australian Central Standard Time zone. These central portions of the country are offset by being a half-hour behind the east (Australian Eastern Standard Time) coast but an hour and a half ahead of the state of Western Australia (Australian Western Standard Time).

In Canada, much of the province of Newfoundland and Labrador is in the Newfoundland Standard Time (NST) zone, which is a half-hour ahead of Atlantic Standard Time (AST). The island of Newfoundland and southeastern Labrador are in NST while the remainder of Labrador along with neighboring provinces New Brunswick, Prince Edward Island, and Nova Scotia lie in AST.

Venezuela's offset time zone was established by President Hugo Chavez in late 2007. Venezuela's offset time zone makes it a half-hour earlier than Guyana to the east and a half-hour later than Colombia to the west.

One of the most unusual time zone offsets is Nepal, which is fifteen minutes behind neighboring Bangladesh, which is on a standard time zone. Nearby Myanmar (Burma), is a half-hour ahead of Bangladesh but an hour ahead of offset India. The Australian territory of the Cocos Islands shares the time zone of Myanmar. The islands of Marquesas in French Polynesia are also offset and are a half-hour ahead of the rest of French Polynesia.

Use the "Elsewhere on the Web" links associated with this article to explore more about offset time zones, including maps.