result, the Earth's rotation around its axis is the change of day and night, the shape of the planet and rejection bodies (moving horizontally) in the northern hemisphere - right in the South - to the left.
full rotation around its axis makes our planet in 24 hours (day). So, after an hour all points of the Earth (except poles) returned to 15 °. Given this fact, the territory of the planet is divided into 24 time zone, which is numbered from west to east - from zero to 23 zone th. Because of the uneven lighting on the globe every meridian at the same time different times of the day, it's called solar or local time. In fact, for ease of use lap time - time the central meridian of each zone. Local Greenwich meridian was adopted as World .
As seen from the map, the boundaries of time zones often do not coincide with the meridians, they actually go through the borders and within the administrative-territorial formations. This is done for convenience. For example, the length of Ukraine in the degree dimension - 18 ° 05 '(width of a time zone 15 °), therefore, our nation was to be in three time zones, but in fact, Ukraine is in one zone.
through the Earth's rotation around the axis of the planet is a conventional line that divides the place in that same time have a calendar date with a difference in one day. This line is mainly on 180 th meridian line and called Date Line .