What is the international date line line?

Answer 1

The International Date Line was established, beginning in 1917, as the arbitrary line of longitude at which a calendar day is said to begin.

Because the Earth rotates, and any clock hour could be local time somewhere in the world, a location was chosen to be the dividing point between calendar days.

As Greenwich was chosen as the central point of the Earth's lines of longitude, noon at Greenwich (when the Sun is directly overhead) was designated as midday. It follows therefore that on the other side of the planet, 180 degrees from Greenwich, it would be midnight, the ending of one calendar day and the beginning of another.

This line, which is 180 degrees east or 180 degrees west longitude, is therefore the line on which one day ends and a new day begins. The line runs through the Pacific Ocean from the North Pole to the South Pole passing between Russia and Alaska. The actual Date Line diverges from the meridian to accommodate national boundaries : eastward for Russia, westward for the Aleutians, and eastward for Pacific island groups and New Zealand.

At any time other than midnight, it is a different day on either side of the International Date Line. If you cross it heading west, you add a day. If you cross it going east, you subtract a day (in addition to making the hourly time changes, backward or forward, respectively).

Answer 2

The international date line is a line that separates days, like if it is Monday in the U.S, it is Tuesday in Austrailia. Going west across the line makes you lose a day. Going east across the line makes you gain a day back.

Answer 3

Bob the builder eats cheese!