international date line

Since the world is divided into 24 time zones there must be a point where one day ends and another day begins.

Exactly 180 degrees around the Earth (one half turn) from the Greenwich Meridian lies the line where our day and date can change. Travel from East to West across the line and you add an extra day - you get the day you have just had back again. Travel from West to East across the line and the opposite occurs - you lose a day.

Sometimes countries can play with the position of the dateline for strange reasons. On 23rd December 1994 The Republic of Kiribati announced that:

This perfectly reasonable decision from an administrative point of view, puts a large eastward bulge in the International Date Line. It also placed Caroline Island, since renamed Millennium Island, as a leading contender to see the first sunrise of the new millennium.

The International Date Line has no astronomical or physical meaning. It now wanders from beginning to end to avoid cutting countries into two days. Now you can travel across Kiribati without missing or repeating a complete day!