The International Date Line (IDL) is an imaginary line located approximately along the 180° meridian, on the opposite side of the Prime Meridian. It serves as the boundary where the date changes. When you cross the IDL from east to west, you subtract a day, and when you cross from west to east, you add a day.
Here are some key points about the International Date Line:
- Purpose: It helps to keep time consistent around the world. Since the Earth is divided into 24 time zones, the IDL ensures there is no confusion about the date when crossing time zones.
- Not a Straight Line: Although it is often depicted as a straight line, the IDL is not perfectly straight. It zigzags to avoid splitting countries and territories into different dates. For example, it detours around some Pacific islands to keep them within the same time zone.
- No Time Zone: The IDL itself is not in any particular time zone. It’s just a reference point where the date changes, and it’s used to calculate local times in relation to the time zones around it.
- Across the Pacific Ocean: The IDL generally runs through the middle of the Pacific Ocean, passing through the Bering Sea (between Alaska and Russia) and making a few deviations to avoid islands that would otherwise end up on different days.