The Earth rotates on its axis 360 degrees a day. Since the sun does not shine light around the whole Earth at once, or at different places at the same time (like Britain and Russia) we need time zones. The time zones specify the time of day for the particular region. For example the US crosses 6 time zones. From the earliest time zone, Eastern Standard Time (east coast) to the latest time zone, Alaskan Standard Time; is a difference of 5 hours. Since the US is over 4,000 miles long (Alaska to Maine) , the sun does not shine on the whole US at the same time due to rotation.
