The International dateline.
When you cross the International Date Line traveling from Asia to North America, you will lose a day. This is because the Date Line serves as the boundary for calendar days; when you cross it from east to west, you subtract a day. For example, if it's Monday in Asia, upon crossing the Date Line, it will be Sunday in North America.
When you cross the International Date Line, you move from one day to the next. This imaginary line on the Earth's surface marks the change in calendar days.
In that direction, you turn your calendar ahead 24 hours when you cross the line.
When crossing the line from west to east, you take the last page that you tore off of your calendar, and you glue it back on.
you go back a day from the day you are on
The International Dateline.
the international date line
Nothing in particular happens; if you happen to be napping aboard the ship at the moment of crossing, you can sleep right through it, just as you do when crossing any other meridian of longitude. By international agreement, however, your calendar date becomes one less when you cross the International Date Line going east.
To change the calendar date when traveling, you must cross the International Date Line, which is located roughly along the 180th meridian in the Pacific Ocean. When you cross this line eastward, you subtract a day, and when you cross it westward, you add a day. This imaginary line helps account for the Earth's rotation and the 24-hour time zones.
Because when flying either to Japan or America, you cross the International Date Line.
Going west, you must tear the current day off of your calendar and dispose of it when you cross the IDL. Immediately as you cross, the date becomes one day later. It's not necessary to do anything to your watch, unless it's a calendar watch. If it is, then you do whatever you must in order to make it indicate one day later, but you make no change to the time.